26 August 2025, Volume 46 Issue 8

    

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  Study on the Optimization Potential of Improved Dual-pressure ORC Based on the Advanced Exergy Analysis

  YANG Xinle, ZHAO Chenyu, BU Shujuan, LI Weikang, YU Ning, DAI Wenzhi

  Journal of Engineering Thermophysics. 2025, 46(8): 2441-2452.

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  In order to solve the problem of mismatch between heat source temperature and evaporation pressure in low-pressure stage, a double gas-liquid separator (DS-DPORC) system was proposed based on the basic dual-pressure organic Rankine cycle (DPORC) system. The thermal performance of DPORC and DS-DPORC system is compared and analyzed. Both traditional and advanced exergy analysis methods were used to study the improvement potential and interaction relationship of the optimized DS-DPORC system and its components. It is shown that there is an optimal evaporation pressure at high and low-pressure stages, respectively, which enables the thermal performance of both systems to reach the optimal level. At that time, DS-DPORC had a 10.02% increase in net output compared to DPORC, while the exergy efficiency increase was 10.4%. There are differences between traditional and advanced exergy analysis methods. The former thinks that the preheater with the highest exergy destruction has the greatest potential for improvement, while the latter thinks that the high-pressure turbines has the highest priority for improvement considering both the exergy destruction rate and the exergy destruction. In addition, exergy destruction of various components in the DS-DPORC system mostly belongs to internal exergy destruction, and the exergy destruction of components is relatively poor in inter dependency.
  
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  Mn-doped Modified Steel Slag for Calcium-Based Thermochemical Energy Storage Characterization

  LI Wenjie, LI Chenguang, LEI Shaomin, GUO Xin

  Journal of Engineering Thermophysics. 2025, 46(8): 2453-2462.

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  Calcium cycle technology (CaL) is highly compatible with concentrated solar power (CSP) plants due to its high temperature resistance and high heat storage density. However, the poor stability of CaO cycle and poor light absorption performance limit the overall efficiency of the system. In this study, steel slag was used as a raw material to prepare novel calcium-based materials by acetic acid impregnation and doping with different ratios of manganese. The results showed that the material doped with 5% manganese had the best performance. Through thermogravimetric tests and 30 cycles of thermal storage experiments, the adsorption rate is increased by 85% and the energy storage density is increased by 73% compared with CaO. In addition, its light absorption rate is 9.5 times that of CaO. The light-driven simulation experiments also further validate its potential for application in the system, demonstrating a wide range of prospects for use in next-generation CaL-CSP systems.
  
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  Performance Analysis of a Water-Based Photovoltaic-Thermal Heat Pump System Using Different Solar Cells

  LIU Lei, JIANG Shan, LI Xinsheng, JIA Teng, ZHAO Yao, DAI Yanjun

  Journal of Engineering Thermophysics. 2025, 46(8): 2463-2470.

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  A simulation study has been conducted on a water-based Photovoltaic-Thermal (PVT) heat pump system using different types of solar cells. An energy loss model for photovoltaic (PV) modules and a thermodynamic model for the PVT heat pump system are established and experimentally validated. The energy distribution of three high-efficiency monocrystalline silicon (c-Si) PV modules—PERC (Passivated Emitter and Rear Cell), TOPCON (Tunnel Oxide Passivated Contact), and HJT (Heterojunction with Intrinsic Thin-film)—is analyzed at different temperatures, and the temperature coefficients are calculated. The temperature sensitivity varies for different types of PV cells. The HJT module exhibits the lowest temperature coefficient at −0.27% among them. The performance of the PVT heat pump system based on three c-Si solar cells is compared on typical days throughout the year. The results indicate that the power generation efficiency of the HJT module is improved by 12%∼15% compared to PERC, while the average COP is slightly reduced by 0.8%∼1.3% compared to the PERC system. Therefore, using high-efficiency photovoltaic modules is an effective way to improve quality and efficiency in PVT heat pump systems. The system’s COP in summer could reach 7.11, while the COP in winter is 4.62.
  
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  Thermodynamic Analysis of S-CO₂ Mixture Working Fluid Brayton Cycle System in Low Temperature Environment

  NIU Xiaojuan, FU Yanan, LEI Youzhe, YUE Guilei, QI Lei, HONG Wenpeng, SI Heyong

  Journal of Engineering Thermophysics. 2025, 46(8): 2471-2480.

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  When the supercritical carbon dioxide(S-CO₂) Brayton cycle is applied to low temperature cold source scenarios such as deep sea and polar regions, the compressor inlet temperature is limited by the critical point of CO₂ (30.98°C) and cannot be further reduced, the critical temperature of CO₂ can be adjusted by adding the second component of working medium to CO₂, which is expected to improve the cycle thermal efficiency while adapting to the low ambient temperature. In this paper, the thermodynamic performance of S-CO₂ mixed-work mass Brayton cycle system under low-temperature environment is analyzed, and SF₆, Xe, Kr, and Ar gases are selected as the additive work masses to analyze the effects of main compressor inlet temperature, turbine inlet temperature, turbine inlet pressure, and diversion ratio on the thermal efficiency of the system cycle with different work masses and different critical temperatures. The results show that the addition of the above additives can improve the thermal efficiency of the cycle, among which the addition of Xe and Kr has the greatest improvement on the cycle thermal efficiency. The optimal cycle thermal efficiency of CO₂-Xe and CO₂-Kr are increased by 2.4% and 2.3% compared with pure CO₂ at a critical temperature of 14°C for the mixture working fluid.
  
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  Mathematical Modelling and Optimization of Cesium Thermionic-thermoelectric Hybrid Generation System

  MA Fangwei, ZHANG Haochun, DENG Minghao, LUO Xi

  Journal of Engineering Thermophysics. 2025, 46(8): 2481-2491.

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  In this study, a mathematical model of a static hybrid power generation system composed of a cesium thermionic energy converter (CTEC) and a thermoelectric generator (TEG) was established. The model takes into account the irreversible heat loss and additional energy barriers of the CTEC module, as well as the Thomson effect of the TEG module. The effects of the CTEC output voltage, anode work function, and TEG current on the system’s output power and conversion efficiency were investigated. The results show that the output power and conversion efficiency of the hybrid power generation system exhibit a parabolic relationship with the increase of the CTEC output voltage. Reducing the anode work function is beneficial for improving system performance, while the TEG current has a minor impact on the system. The optimal operating region of the system was determined by analyzing the relationship between efficiency and output power, providing a reference for the optimal design and application of CTEC-TEG hybrid power generation systems in the future.
  
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  Integration of CO₂-coal Gasification Coupled Green Hydrogen to Produce Methanol System

  ZHENG Yawen, WANG Junyao, LIU Jianhui, HE Song, ZENG Xuelan, YANG Guang

  Journal of Engineering Thermophysics. 2025, 46(8): 2492-2504.

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  Traditional coal-based chemical industry suffered from high energy consumption and large CO₂ emission. To improve the energy efficiency and reduce the CO₂ emission, a novel chemical production system was proposed by integrating indirect CO₂ hydrogenation with coal-based chemical industry. In this paper, methanol production system was selected as a case to investigate the thermodynamic and environmental performance. Results showed that the optimal operating conditions for the new system are a CO₂/coal ratio between 0.2∼0.25 and an O₂/coal ratio between 0.75∼0.8. At this point, the system’s energy efficiency and coal saving rate are around 57% and 56% respectively. Compared with direct CO₂ hydrogenation system and traditional coal to methanol system, a coal saving ratio of 56.4% can be achieved by providing carbon-free H₂ and electricity. Furthermore, the combination of CO₂ utilization and electrification using renewable energy contributed to the carbon utilization efficiency of 94.8% and a negative CO₂ emission of 0.06 t (CO₂)/t (methanol) in the proposed system. While the carbon utilization efficiency and the net CO₂ emission of traditional coal to methanol system were 32.6% and 2.8 t (CO₂)/t (methanol), respectively. And when the price of renewable electricity drops to 0.15 to 0.20 yuan/kWh, the new system has a significant economic advantage with production costs of methanol production ranging from 1900 to 2300 yuan/t. Therefore, the proposed system provided feasible technical solutions for coal-based chemical industry to realize both low-carbon emission and efficient chemical energy conversion.
  
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  Progress of Researches on Thermophotovoltaic Emitters Based on Micro-Nano Metamaterial Structures

  YUAN Kunpeng, CHEN Binghong, XU Junhan

  Journal of Engineering Thermophysics. 2025, 46(8): 2505-2519.

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  Micro and nano metamaterial structures have been widely used in the research of selective heat emitters in thermophotovoltaic systems due to their tunable selective absorbing or radiating properties. In this paper, based on the photovoltaic cells commonly used in thermal photovoltaic systems, the idealized radiation spectroscopy analysis is carried out for the external quantum efficiency of several photovoltaic cells. Then the spectral control mechanism of metamaterial emitters is explained and their performance indexes are analyzed based on literature research. Finally, according to the radiation spectrum, the existing metamaterial emitter structures are summarized and the experimental research on thermophotovoltaic systems is summarized in chronological order, and some countermeasures are listed in the prospect part for the challenges of current technology development. So as to provide theoretical guidance for the development of thermophotovoltaic technology in the future.
  
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  Numerical Study on the Effect of Gradient Composition Anode on the Electrochemical Performance of SOFC

  FU Pei, CAO Ziqiang, CHEN Ying, XIE Yang, LIU Qingshan, CHEN Yisong

  Journal of Engineering Thermophysics. 2025, 46(8): 2520-2531.

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  Solid oxide fuel cell (SOFC) is an innovative green energy technology. It efficiently uses hydrogen energy and has a wide range of applications, which helps transform China’s energy structure. For planar anode-supported SOFCs, the gradient anode design is considered to be an important structural feature that can enhance the overall performance. This study numerically investigates the gradient composition anode SOFC. Under isothermal conditions, three-dimensional multi-physics coupling models are established. These models simulate the gas transport and electrochemical reaction processes in the SOFC. By comparing the mass transfer and electrical performance of homogeneous composition anode and gradient composition anode SOFCs, this study analyzes the influence mechanism of gradient composition anodes on SOFC performance. This analysis reveals the superiority of the gradient composition anode design. It is found that in the homogeneous composition anode SOFCs, as the volume fraction of electronic conductor increases, the hydrogen mole fraction in the anode channels and porous anodes increases. The hydrogen mole fraction distribution in the gradient composition anode is higher than that in the homogeneous composition anode. This indicates that the gradient composition anode can effectively improve the cell’s mass transfer performance. Compared with homogeneous composition anode SOFCs, the gradient composition anode SOFC doesn’t show significant advantages in reducing activation polarization and ohmic polarization losses. However, it can significantly reduce the concentration polarization losses, thus lowering the total polarization loss of the SOFC anode. In this study, the maximum output power density of the gradient composition anode SOFC can reach 1.24 W·cm⁻², which is 28.40%, 9.13%, and 10.68% higher than that of the homogeneous composition anode SOFCs with electronic conductor volume fractions of 0.65, 0.50, and 0.40 respectively. Evidently, the gradient composition anode design can significantly improve the electrical performance of SOFC. This research can provide theoretical guidance for the optimization design of gradient anode compositions in SOFCs.
  
  
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  Research on the Performance of Helical Runner Solar Ordered Hydrogen Production Reactor

  LI Liang, SU Bosheng, YUAN Shuo, CAI Jiahao

  Journal of Engineering Thermophysics. 2025, 46(8): 2532-2543.

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  In order to solve the problem of non-uniform light spots produced by disc solar concentrators, this study provides a new way of thinking. Based on the matching between the heat absorption characteristics of the chemical reaction itself and the temperature field of the heating surface, a novel helical flow channel solar ordered hydrogen production reactor matching the temperature gradient of the concentrator spot is designed. By introducing the spiral reaction process, the maximum temperature difference of the heating surface of the reactor is reduced from 450 K to 279 K, which can significantly improve the physical properties of the reactor material and alleviate the material fatigue and safety problems caused by the uneven light gathering in the reactor. Compared with the disk reactor, it is found that under the same suitable boundary conditions, the maximum temperature difference of the absorption surface of the helical flow channel solar ordered hydrogen production reactor is reduced by 200 K, the relative conversion rate of methane is increased by 7.6%, and the relative thermal chemical utilization efficiency of solar energy is increased by 9.8%. 
  
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  Research on the Parametric Design Method of Supersonic Compressor Blade Profile Based on Precise Control of Leading and Trailing Edges

  TANG Yu’an, YANG Chengwu, ZHAO Shengfeng, LU Xingen, DENG Kunying

  Journal of Engineering Thermophysics. 2025, 46(8): 2544-2556.

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  The supersonic compressor blade profile is faced with some problems, such as the increase of shock wave loss and the intense interaction between shock wave and boundary layer. The modeling method of supersonic blade profile has a significant effect on the flow and loss of the blade. Therefore, the inlet Mach number, the inlet angle and the design parameters of the blade inlet are correlated based on the theory of the unique incidence. A parameterized modeling method for supersonic compressor blade profiles was developed based on multi-stage low-order Bezier curves, incorporating a precise control method at the leading and trailing edges. The ARL-SL19 blade profile is fitted using the parameterization method, and the high precision of the modeling method is verified by Fluent numerical calculation. Based on this, a supersonic blade profile with inlet Mach number range of 1.6∼1.7 is designed, and the effects of throat area and throat position on cascade flow and performance are investigated. The results indicated that throat parameters impact the performance and flow of supersonic cascades mainly by altering the structure of the shock wave system, and the throat area ratio is the key factor affecting the total pressure loss. The smaller the throat area ratio and the higher the throat position, the smaller the total pressure loss coefficient, but the smaller the effective range of work.
  
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  The Influence of Non-Axisymmetric Endwall on the Incidence Characteristics of a Compressor Cascade

  GUO Hanwen, JIN Donghai, YU Hao, ZHANG Jiancheng, DAI Yucheng, LIU Xiwu, GUI Xingmin

  Journal of Engineering Thermophysics. 2025, 46(8): 2557-2565.

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  The influence of non-axisymmetric endwall on the incidence characteristics of a compressor cascade is investigated using a three-dimensional inverse design method. The inverse design method specifies the static pressure distribution on the endwall and iteratively derives the corresponding endwall shape, thereby integrating flow mechanisms into the design process. A critical aspect of the inverse design is the quantitative determination of an appropriate endwall pressure distribution. The cross-passage pressure distribution on the endwall is determined by employing a dynamic model of cross-flow. The effects of the non-axisymmetric endwall (designed at 0 degrees incidence) on corner flow are analyzed at various incidence angles. The results indicate that, while maintaining the pressure difference between the suction and pressure surfaces, locally enhancing the cross-flow near the suction side in the rear part of the passage can direct higher-velocity fluid of the endwall boundary layer into the corner region, thereby suppressing corner separation. Within an incidence range of −4 to +8 degrees, corner separation is effectively controlled. The flow control effect is most pronounced at +4 degrees incidence, where the total pressure loss of the cascade is reduced by 13.5%.
  
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  Scale of Coherence and Acoustic Field Analysis in Hot Jets

  LI Hongru, LIU Qilin, LAI Huanxin

  Journal of Engineering Thermophysics. 2025, 46(8): 2566-2575.

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  In order to explore the influence of temperature on aerodynamic noise in jet flows, large eddy simulations of hot jets at Mach number M = 0.9 and ratio of nozzle temperature to ambient temperature T_j/T_∞ = 2.0 and 3.4 are carried out in this paper so as to analyze the self-similar statistical characteristics of the flow field. In response to the deficiencies of the even coherence function model based on characteristic scales in literature, the upstream-downstream asymmetry of the coherence function in the hot jet is paid attention. A semi-empirical model is proposed for sound field prediction using the wave packet concept. The improved prediction of the far-field at small angles dominated by large-scale structures is shown. The model is further simplified by using a simplified linear fitting method based on characteristic scales, the results show that this linear model can also have good predictions. The influence of the parameters of the linear model is further discussed.
  
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  Study on Acoustic Signature of Low Specific Speed Centrifugal Pump Based on LES-FEM Method

  GU Jiarong, GAO Bo, NI Dan, ZHANG Ning, WANG Feifan

  Journal of Engineering Thermophysics. 2025, 46(8): 2576-2583.

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  In order to investigate the distribution characteristics of flow induced acoustic of low specific speed centrifugal pumps, the hybrid method of large eddy simulation (LES) combined with finite element (FEM) is utilized to solve the internal sound source characteristics under different working conditions. The frequency domain response characteristics of acoustic and the contribution of the different sources to the acoustic are obtained. Furthermore, the frequency spectrum is transformed to elucidate the temporal variation of acoustic, using the Fourier inverse transform (IFFT). Results demonstrate that the sound power level located in the impeller outlet is higher than other region due to the dynamic and static interference (DSI). The blade dipole acoustic is mainly excited by the pulsating loads acting on the blade surfaces, manifests as typical broadband noise. With an increase in flow rate, the blade load increases, leading to a higher overall average sound pressure level at the pump outlet. The volute dipole noise, mainly excited by the interaction between stationary and moving parts, exhibits a typical tonal noise distribution. The amplitude of discrete signals of the blade frequency component is significant and increases with the flow rate.
  
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  Coupling Characteristics of Typical Cylindrical-Hole Film Cooling and Thermal Barrier Coatings for Turbine Vane

  PU Jian, ZHAO Wei, ZHAO Qingjun, ZHU Zhihao, LUO Weiwei, MA Guangjian

  Journal of Engineering Thermophysics. 2025, 46(8): 2584-2596.

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  To establish the optimal design method of film cooling coupling with thermal barrier coating (TBC) in the near-hole region for turbine vane, this work discussed the effects of coupling type of both the thermal protection methods on the metal overall effectiveness of film-cooled plates with different curvatures, when the thermal resistance of TBC and the cooling air flowrate varied. Two coupling types were selected to form two coupling models. The first model was a film-hole embedded in TBC, causing the metal in near-hole region to expose in the hot gases. The second model was a film-hole directly sprayed by TBC. The film-hole in this work was a typical cylindricalhole. The metal overall effectiveness was captured by conjugate heat transfer simulations. The numerical results revealed that the first model has insignificant benefits on thermal protection when both the thinner TBC and smaller cooling air flowrate were employed. When the TBC was thickened, the metal overall effectiveness can be improved by up to 200%∼300% through applying the first model with the proper embedded-shape, in comparison with the second model. However, the much larger processing difficulty can be achieved by employing the first model, due to the larger sensitivity of metal overall effectiveness to the parameter of embedded-shape. When the second model was applied, the hole-exit can be blocked by the TBC particles, inducing the reduction in the film effectiveness. The blocked-hole with enlarged diameter can achieve the same-level cooling effectiveness to the original-designed film-hole, when the effective blowing ratio was proposed in the design stage.
  
  
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  Matching Analysis Method of Multi-Compressor Series-Parallel Compression System

  WANG Xiaochen, GU Chunwei

  Journal of Engineering Thermophysics. 2025, 46(8): 2597-2605.

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  Industries such as compressed air energy storage raise critical requirements on operation ranges of pressure ratio and mass flow of compression systems. Multi-compressor series-parallel design is adopted to achieve safety and stability under complex operation conditions, and accurate prediction and controlling strategies of system aerodynamic matching faces great challenges. A through-flowbased matching analysis method of multi-compressor series-parallel compression systems is proposed in this paper. The prediction models are established based on an in-house two-dimensional throughflow tool of axial compressors, coupling through-flow calculations with one-dimensional characteristics of pipe components The quasi-steady matching performances of the compression system can be analyzed for loading and start/stop processes. For a specific preliminary design of the multicompressor series-parallel system, matching analysis is conducted for operation windows and the start/stop process under varied operation modes. The impact mechanisms of controlling strategies such as bypass bleeding and IGV opening are discussed on the start/stop characteristics and matching performances. This study provides an enhanced and reliable method for the design, analysis and operation of multi-compressor systems
  
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  Study on CO₂ Capture and Ammonia Emission in Amino Solution of Hybrid Additive

  YANG Ning, CHUAI Yuheng, TANG Hongqiang, HAO Jingyang, GAO Shiwang, BAO Zhiming, JIAO Kui

  Journal of Engineering Thermophysics. 2025, 46(8): 2606-2613.

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  The ammonia slip issue in ammonia-based carbon capture leads to environmental pollution and solvent loss, restricting its industrial application. This study synthesized Fe₃O₄@SiO₂ nanoparticles and mixed Ni²⁺/Co²⁺ metal ion additives, investigating their synergistic mechanism in aqueous ammonia solutions. Combined with gas-liquid mass transfer analysis, the effects of additives at different concentrations on the performance of ammonia-based carbon capture were examined. Results showed that when the concentration of Fe₃O₄@SiO₂ nanoparticles reached ω(Fe₃O₄@SiO₂) = 0.27, the CO₂ absorption performance achieved the optimal state with an absorption rate of 56.28%. the concentration of Ni²⁺/Co²⁺ is 0.09 mol/L, the ammonia inhibition rate is optimally 54.19%. To address the ammonia slip issue, Ni²⁺/Co²⁺ additives were added to the aqueous ammonia solution containing Fe₃O₄@SiO₂ nanoparticles. The absorption rate, and ammonia slip suppression of the mixed additives fell between those of the solutions with sole Fe₃O₄@SiO₂ nanoparticles or sole Ni²⁺/Co²⁺ additives, balancing carbon capture capacity while reducing ammonia emission.
  
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  Study on Multi-scale Energy Distribution Characteristics of Gas-liquid Two-phase Flow in an Upward Pipe

  LI Nailiang, LIU Liwen, LIU Changsong, DU Xueping

  Journal of Engineering Thermophysics. 2025, 46(8): 2614-2621.

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  The dynamic characteristics of gas-liquid two-phase flow in upward pipes is the basis for accurate identification of flow patterns. In this study, the interphase interaction mechanism of bubble flow, slug flow, annular flow, and severe slugging flow of air-water two-phase flow in an upward pipe was experimentally studied from the perspective of energy distribution. Based on the multi-resolution analysis method, the time series of the pressure difference signal was decomposed into 1∼8 scales using the db2 wavelet, and the dimensionless energy of the detailed components of the pressure difference signal for each flow pattern was calculated, with a purpose to reveal the multiscale energy distribution mechanism of the flow pattern. It was found that the energy distribution of bubbly flow exhibits a bimodal structure, while the energy distribution of annular flow, slug flow, and severe slugging flow show a unimodal structure. The energy and the scale corresponding to the peak of the multi-scale energy distribution curve for each flow pattern is presented. The energy distribution characteristics of flow patterns are quite different from each other, implying that multiscale energy distribution of differential pressure can be used as an effective approach for recognition of flow regimes in upward pipes.
  
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  Radial Mixing and Separation of Binary Density Ellipsoids in a Rotating Drum

  XIE Lei, DING Nuo, SHAN Jipeng, CHEN Hua, WANG Shuyan

  Journal of Engineering Thermophysics. 2025, 46(8): 2622-2629.

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  This study employs the Discrete Element Method (DEM) to investigate the radial mixing and segregation behaviors of binary ellipsoidal particles with varying densities in a rotating drum. The ellipsoidal particles are modeled using a multi-sphere method. The effects of particle aspect ratio and density ratio on mixing efficiency and segregation extent are thoroughly examined. The simulation results indicate that light particles tend to occupy the wall region of the granular bed, whereas heavy ones are concentrated in the central region. As particle aspect ratio deviates from 1, i.e. oblate or prolate shape, the mixing index increases, while the final degree of segregation decreases. During the motion process, particles primarily undergo translational movement, whereas ellipsoidal particles are more susceptible to rotational motion. A decrease in the particle density ratio leads to an increase in the degree of segregation, while the translational kinetic energy rises with an increase in the density ratio. Compared to heavy particles, the rotational kinetic energy of light particles is more sensitive to changes in the density ratio.
  
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  Experimental Study on the Effect of Surface Temperature for the Splashing After Fuel Droplets Impacting on the Surface

  靳爽, 张卫正, 郭镇瑶, 颜杰, 原彦鹏, 石智成

  Journal of Engineering Thermophysics. 2025, 46(8): 2630-2640.

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  To reveal the mechanism of surface temperature on the splash phenomenon after fuel droplet impingement, a modular optical experimental system was built to visualize the effect of surface temperature on the splash phenomenon after droplet impingement. The results show that the different dynamic behaviors after droplet impacting on the surface with different temperature are observed, such as deposition, splashing, break-up, secondary atomization and rebound, at the surface temperature of −40∼400°C and Weber number of 42∼720. The corona splash can be divided into two sub-patterns: the corona structure breaking after the edge falling off and the annular or finger disintegration after the corona directly breaking. This is mainly caused by the instability difference of the driving corona edge falling off and the corona structure breaking. As the rise of surface temperature inhibits the formation of corona structure, the splash phenomenon gradually decreases, and the quantitative parameters(dimensionless diameter and height) of corona structure decrease with the higher surface temperature. The influence of surface temperature on splashing is summarized as heat transfer in the formation of liquid sheet and the aerodynamic action of air with varying temperature near the surface after the corona formation. Based on qualitative temperature assumptions and theoretical analysis, a prediction model of splash threshold after droplet impacting on non-isothermal surface is established, and the model can better predict the experimental results in this study and related literature.
  
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  Numerical Simulation Study of Icing on a Wide-Speed Aircraft Based on Discrete Multiphase Flow

  SUN Zhixin, LIU Hantao, LI Haiqiao

  Journal of Engineering Thermophysics. 2025, 46(8): 2641-2651.

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  This study establishes a three-dimensional ice accretion model for wide-speed aircraft based on discrete multiphase flow theory. The airflow field was solved using Reynolds-averaged N-S equations coupled with a k-ε turbulence model, while droplet trajectories and wall impingement rates were calculated via the Eulerian method. Dynamic mesh techniques were employed to reconstruct surface grids during ice formation, and multi-timescale simulations were conducted to characterize ice-layer evolution. The effects of angle of attack and geometric configuration on droplet impingement characteristics, ice morphology, and spatial distribution were systematically investigated. Key findings reveal that increased leading-edge bluntness in subsonic wing-body configurations enlarges droplet shielding zones on both upper and lower surfaces. For wide-speed aircraft employing diamond-shaped thin airfoils with sharp leading edges, broader droplet impingement coverage leads to extensive ice accumulation, predominantly localized at the fuselage nose, wing leading edges, and vertical tail surfaces. Wide-speed aircraft wings have icing characteristics with smaller ice shapes for larger swept-back angles, and no icing was observed on the side-strip wings. Increasing the angle of attack shifts ice accumulation toward the tip and outer regions of the vertical tail, whereas augmenting wing sweep angles reduces droplet impingement rates by up to 75%, effectively suppressing ice growth. Critical aerodynamic degradation is observed under iced conditions, with a 13.6% reduction in lift-to-drag ratio at AOA=8°. These findings establish a quantitative framework for understanding ice distribution mechanisms and provide actionable insights for anti-icing design optimization in wide-speed aircraft.
  
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  Research Progress of Capacitive Deionization Technology in Ion-selective Separation

  GU Haibo, SHI Ruihan, SHEN Zibo, GU Yihao, LI Zhuo, MAO Yunfeng, TAO Wenquan

  Journal of Engineering Thermophysics. 2025, 46(8): 2652-2659.

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  As an emerging ion separation technology, capacitive deionization (CDI) is well known for its ability to selective removal of targeted ions, and has attracted extensive attention in the fields of environmental protection and energy conversion in recent years. This article delves into the distinctive CDI advantages in ion-selective removal, focusing on the characteristics of electrode pore structure, the application of numerical simulation methods in CDI research, and the analysis of its research developments. In terms of electrode pore structure characteristics, we analyze the studies on selective adsorption of cation and anion and propose three hypotheses about selectivity: valence-type, affinity-type, and size-type. We also discuss the underlying selectivity mechanisms of CDI under various effects. In terms of numerical simulations, we summarize the application of macroscopic mass transfer models, Lattice Boltzmann methods, and Molecular dynamics simulations in CDI research, demonstrating their crucial roles in the analysis and optimization of the adsorption process in CDI. By summarizing and analyzing the current state of CDI selectivity research, we aim to provide valuable insights for further in-depth exploration of this technology.
  
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  Prediction of Thermal Conductivity of Multi-media Composites Based on Model Coupling

  MA Lingyong, LI Xinyao, WANG Zhiguo, LIU Yang, LI Qing

  Journal of Engineering Thermophysics. 2025, 46(8): 2660-2668.

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  Enhancing the thermal storage performance of building materials and their utilization of solar energy is an effective way to realize energy saving in buildings. In this paper, a new multimedia composite building energy storage material is investigated, the calculation model of thermal conductivity applicable to this material is proposed, and the calculation model is compared and analyzed through material preparation and experiments. It is found that the equivalent thermal conductivity derived by coupling the generalized self-consistent model with the equivalent medium theoretical model is in line with the results of experimental tests and the series-parallel model, and is suitable for predicting the equivalent thermal conductivity of the material in this kind of structure. As the content of phase change glass beads increases, the overall thermal conductivity of the material is smaller and the thermal storage performance is better, and the process shows a linear trend. 
  
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  Effect of Nanoparticles on Spectral Radiation Characteristics of Alumina Foam Ligament Surface

  LIU Bo, FENG Jie, SHI Guohua, WANG Ziang

  Journal of Engineering Thermophysics. 2025, 46(8): 2669-2675.

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  The spectral radiation characteristics of alumina foam ligament can be effectively affected by the attached nanoparticles on the surface. In this paper, nanoparticle structure models with Au solid sphere structure, Au-Si two-layer core-shell structure and Au-Si-Au three-layer structure are constructed, and the size parameters are changed. The spectral absorption factors of different particle structures at 200∼2000 nm waveband are calculated by the FDTD method, and the difference in local electromagnetic fields caused by nanoparticles is compared. At the same time, the spectral reflectance of the constructed different micro-scale models is calculated, and the influences of nanoparticles on the radiation characteristics of the skeleton surface are analyzed. The results show that nanoparticles with Au-Si double-layer core-shell structure have better spectral absorption characteristic in broad waveband and own obvious spectral regulation characteristic. The absorption performance can be effectively enhanced by attaching nanoparticles to the surface of alumina foam ligament. The optimization of structural and size characteristics of nanoparticles can regulate the radiation properties at different wavelengths.
  
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  Experimental Study on the Submerged Jet Cooling of Dielectric Liquid With Blade-plate Configuration

  SUN Zhihao, ZHANG Ziyao, YI Hongliang, WU Jian

  Journal of Engineering Thermophysics. 2025, 46(8): 2676-2683.

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  The flow technology driven by active electric field has the inherent advantages of no moving parts, intelligent control, low power consumption and low vibration, which is very suitable for thermal management in microgravity space. In this paper, the heat transfer and flow characteristics of 25# transformer oil’s submerged jet cooling driven by electric field in asymmetric blade-plate electrode configuration are studied. The experimental results shows that the average Nusselt number of heat transfer increases with the applied electric field intensity. The effect of heat transfer enhancement is more obvious when the blade electrode is applied negative voltages. The average Nusselt number can be increased by up to 82.5%, and the power consumption of electric field is only 0.036 W. The Coulomb force is the dominant force for electric field acting on the flow and heat transfer enhancement.
  
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  An Experimental Investigation on Cooling Characteristics of Combined Sublimation and Transpiration Cooling Using TFE Materials

  MA Yulong, LÜ Yumei, WU Wanfan, WU Nan, HE Fei, WANG Jianhua

  Journal of Engineering Thermophysics. 2025, 46(8): 2684-2692.

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  Sublimation-transpiration cooling is an advanced active and passive integrated cooling technology. By coating the surface of porous structures with sublimable materials, it can achieve efficient cooling and adaptive cooling in local hot areas, which can be used to solve the thermal protection problem of space vehicles in extreme thermal environments. The thermal response characteristics and cooling effect of three TFE (tetrafluoroethylene polymer) coating materials (PTFE, ETFE, PFA) were studied by using high temperature spray gun and high temperature wind tunnel test platform, and the cooling mechanism of the non-steady state process of the combined sublimation and transpiration cooling technology was analyzed. The results show that the temperature variation of the structure surface is mainly affected by the thermal properties of the coating material, and the temperature distribution of the structure surface is affected by the coupling of the high temperature main stream and the phase change of the coating material. Compared with the other two tetrafluoroethylene polymers (ETFE, PFA), PTFE material has better thermal response characteristics and cooling effect.
  
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  Study on Heat Flux Distribution of Multilayer Ring Radiation Heater for Thermal-structural Tests

  XING Hongjie, LIANG Yong, ZHANG Longfei, LIU Bing, ZHOU Zhifu

  Journal of Engineering Thermophysics. 2025, 46(8): 2693-2701.

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  In the structural thermal test of the solid rocket motor, a quartz lamp heater is usually used to heat the motor shell to simulate the aerodynamic heat during high-speed flight. In order to study the uniformity and efficiency of radiation heating generated by quartz lamp heaters with complex structures, a model based on Monte Carlo method is proposed to predict the radiation heat flux of multi-layer ring quartz lamp heaters on the cylindrical shell surfaces. The radiation heat flux measurement system of quartz lamp heater is built, and the accuracy of the radiation model of quartz lamp heater is verified. The maximum average error is 7.44%, and the standard deviation of the error matrix is below 8.74%. Three influence factors on the radiation distribution are investigated, including the neighbor-layer spacing of the quartz lamp arrays, the lamp radiation angle, and the distance between the lamp and the shell. The results show that the distance between the lamp and the shell has the most significant effect on the uniformity of the radiation distributions. Due to the edge effect of the heater, the neighbor-layer spacing will produce a serious radiation trough on the surface. An appropriate radiation angle of the lamp has positive significance for uniform radiation distribution and high radiation efficiency.
  
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  Study on the Vortices and Heat Transfer Characteristics of a Channel Formed by Circular Tube Banks Helically Serrated Fins

  YANG Ruixia, WANG Guolong, WANG Zhaoxia, LIN Zhimin, HOU Bo, WANG Liangbi

  Journal of Engineering Thermophysics. 2025, 46(8): 2702-2714.

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  The instantaneous characteristics of vortex and heat transfer and their relationship in the channel formed by spiral serrated finned tube banks with different structural parameters are studied by using numerical method. The results show that the time-averaged Nusselt number increases with the decrease of the transverse tube pitch, and increases with the increase of the longitudinal tube pitch and the fin pitch. The time-averaged Euler number decreases with the increase of the transverse tube pitch, and decreases with the increase of the fin pitch. The vortex shedding frequency decreases with the increase of transverse tube pitch, and increases with the increase of longitudinal tube pitch and fin pitch. The shedding of the Karman vortex could make the local heat transfer of the finned tube more uniform. When the Karman vortex is not easy to fall off, more heat is transferred from the front row of the finned tube to the low-temperature fluid, but the heat transfer behind the finned tube is significantly worsen, resulting in a larger temperature difference between the front and rear of the finned tube, which is easy to cause local damage to the finned tube. Under the range of structural parameters studied, the fitting relationship between Nu, Eu and St and the range of structural parameters studied in this paper and Re is obtained.
  
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  Numerical Study of Thermophoresis in Double-Walled Carbon Nanotubes

  WANG Yufei, WANG Jun, XIA Guodong

  Journal of Engineering Thermophysics. 2025, 46(8): 2715-2721.

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  In this paper, the thermophoresis in double-walled carbon nanotubes due to temperature gradient is studied by using molecular dynamics (MD) simulations. Owing to the temperature gradient in the inner tube of double-walled carbon nanotubes, the outer tubes can move along the axial direction from high to low temperature. However, it is generally challenging to calculate the thermophoretic force on the outer tube, and the mechanism of the thermophoresis is still unclear. By applying a harmonic force to the outer tube, the thermophoretic force acting on the outer tube can be obtained because of the balance between the thermophoretic force and the harmonic force. The composition of the thermophoretic force consists of two parts the gradient force induced by the potential energy of the interaction between the inner and outer tubes and the edge force induced by the edge potential barrier of the outer tube. It is found that the MD simulation results are in well agreement with the theoretical formulas. The edge force, the gradient force and the thermophoretic force are proportional to the temperature gradient and the mean diameter of inner and outer tube. As the length of the outer tube increases, the gradient force increases gradually. With increasing temperature of the system, the interaction potential energy between the inner and outer tubes is enhanced, which in turn enhances the thermophoretic effect. This paper reveals the thermophoresis mechanism of double-walled carbon nanotubes, which helps to understand the thermophoresis phenomenon on solid surfaces.
  
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  Multi-scale Study of Pollutant Diffusion Under Different Atmospheric Stability

  YANG Feng, WANG Jiaqi, CHEN Yi, CHEN Weiqiu, CUI Pengyi, HUANG Yuandong

  Journal of Engineering Thermophysics. 2025, 46(8): 2722-2729.

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  With the increasing prominence of complex air pollution, the diffusion of air pollutants in trans-scale space has become a hot research topic. This paper uses the CFD numerical simulation method to establish a street-scale air pollutant diffusion model to study the cross-scale motion law of indoor and outdoor pollutants under different atmospheric stability conditions. The results show that stable atmospheric conditions are more unfavorable to the diffusion of pollutants than neutral and unstable conditions, and the staggered arrangement of buildings under the same atmospheric stability conditions is more conducive to the diffusion of indoor and outdoor pollutants than the square arrangement. The conclusion of this study provides a reference for a more comprehensive optimization of urban building layouts.
  
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  Flight Test Research Based on Ultrasonic Non-invasive Temperature and Heat Measurement Technology

  CUI Yue, WEI Dong, LIU Shenshen, DU Yanxia, GUI Yewei

  Journal of Engineering Thermophysics. 2025, 46(8): 2730-2740.

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  To obtain the internal temperature variation characteristics of high-speed aircraft during service, a non-destructive temperature and heat measurement technology method based on ultrasonic acoustic time is proposed to achieve the measurement of the heat flow on the surface of the aircraft structure and the internal temperature field. A mathematical model for ultrasonic temperature and heat measurement is established, a method for ultrasonic temperature and heat measurement is developed, and the measurement device is improved and designed in combination with the actual space flight test. The overall reconstruction deviation of the temperature field obtained from the ground verification experiment is approximately 1.7°C. The influence of the relationship between thickness size, wave velocity and temperature calibration on the ultrasonic measurement results is studied, and the reliability of the ultrasonic temperature and heat measurement method is preliminarily verified. Finally, the ultrasonic device is carried and tested during the space flight test, obtaining the one-dimensional dynamic temperature distribution along the structural wall thickness direction and the heat flow on the outer wall surface at the measurement point position during the flight of the aircraft. The results are basically consistent with the identification results of the temperature sensors pre-set on the inner surface of the aircraft structure. Flight test studies show that the ultrasonic temperature and heat measurement technology method can achieve online monitoring of the internal temperature change characteristics of aircraft structures, providing new ideas and methods for the thermal safety assessment of aircraft structures, and has important engineering application value and prospects.
  
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  Study on the Enhancement Mechanism of Amine Solution CO2 Desorption by 3D Printed Kaolin Catalyst Packing

  MENG Ruping, JIANG Yanchi, JIANG Junfeng, LIU Jian, KONG Chengdong, ZHANG Zhongxiao

  Journal of Engineering Thermophysics. 2025, 46(8): 2741-2748.

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  The use of solid acid catalysts and mixed amine absorbers is one of the effective ways to reduce the energy consumption of absorber regeneration in chemical absorption process. In this paper, solid acid catalysts were fabricated by 3D printing method combined with a continuous bubbling reactor to investigate the improvement mechanism of mixed amine solution regeneration process. Compared with the absorber without added catalyst, the 3D-printed catalyst enhanced the peak desorption rates of 3 mol/L MEA+3 mol/L MDEA, 4 mol/L MEA+2 mol/L MDEA and 5 mol/L MEA absorbers by  3.0, 2.7 and 2.2 times, respectively. This result indicates that the desorption rate enhancement of the mixed amine absorber with the addition of the 3D printed catalyst is better than that of the conventional 5 mol/L MEA solution, which is attributed to the fact that the mixed amine provides more proton acceptors, which reduces the activation energy through diversified proton transfer pathways. Computer vision analysis of the CO₂ bubbles generated by catalytic desorption showed that the radius of the bubbles generated by the 3D-printed catalyst was reduced by about 20%, which increased the gas-liquid interface area, optimised the mass transfer process and enhanced the nucleation, growth and detachment of the CO₂ bubbles, thus improving the kinetic performance of the desorption reaction.
  
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  Three-dimensional Numerical Simulation of Hydrogen/air Premixed Flame Propagation in Closed Tubes

  ZHANG Xiangyu, XIAO Huahua

  Journal of Engineering Thermophysics. 2025, 46(8): 2749-2758.

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  In this paper, three-dimensional numerical simulation of hydrogen/air premixed flame propagation in closed tubes was carried out by solving the three-dimensional (3D), fully compressible, reactive Navier-Stokes equations using a high-precision algorithm in combination with an adaptive mesh refinement technique and a thickened flame model, with an emphasis on the effect of tube width. Numerical simulation results indicate that three-dimensional numerical simulation can reproduce complex flame phenomena such as the tulip flame and the distorted tulip flame observed in experiments. Variations in tube width affect the evolution of the flame front shape along both the width and height directions simultaneously. All cases experience an exponential acceleration phase, where at the same moment, the smaller the tube width, the higher the flame front velocity. The maximum flame front velocity during the exponential acceleration phase increases with the decrease in tube width. In tubes with smaller widths, the boundary layer effect is dominant, leading to the higher flame front velocity compared to tubes with larger widths. The change in tube width mainly influences the pressure build-up rate and does not have a significant impact on the maximum pressure during the entire combustion process or the final pressure upon combustion completion. 
  
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  Simulation of a Double Cyclone Combustion Chamber Based on the ASOM and the IBM Method

  WANG Fang, ZHANG Minqi, WANG Yudong, HAN Yuxuan, JIN Jie

  Journal of Engineering Thermophysics. 2025, 46(8): 2759-2774.

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  Turbulent combustion is prevalent in various power plants, where achieving a balance between high accuracy and efficiency in numerical simulations is crucial. The combination of Large Eddy Simulation (LES) with the Algebraic Second-Order Moment turbulent combustion model (ASOM) offers a promising solution, providing both computational accuracy and efficiency. Furthermore, the Immersed Boundary Method (IBM) proves effective in handling the intricate geometries of combustion chambers with precision. This study evaluates the ASOM model and algorithm using the Flame D algorithm, followed by a comparison of simulation results from the gas turbine model combustor (GTMC) utilizing body-fitted mesh and IBM mesh configurations. The findings indicate that the ASOM model demonstrates remarkable accuracy in turbulent combustion scenarios and exhibits robust suitability for two-phase turbulent combustion problems. Moreover, employing the LES-ASOM model in conjunction with IBM yields substantial reductions in computation time. Specifically, compared to the body-fitted mesh, implementing IBM leads to a six to tenfold decrease in computation duration while maintaining computational accuracy.
  
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  The Influence of Obstacle Thickness on Flame Acceleration in Obstructed Channels

  HUANG Haolei, VALIEV DAMIR

  Journal of Engineering Thermophysics. 2025, 46(8): 2775-2781.

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  This paper, building upon the work of Bychkov et al., further investigates the effect of obstacle thickness on flame acceleration. Through theoretical analysis and numerical simulations, it is found that an increase in the obstacle thickness ratio slows down the flame acceleration process. The paper details a flame acceleration model that takes into account the influence of obstacle thickness and achieves a quantitative prediction of the flame acceleration rate. In the present study, a systematic parametric study is conducted using numerical simulation, focusing on the obstacle thickness, blockage ratio and gas expansion. The simulation results validate the correctness of the model as well as the connection between the finger-like flame acceleration mechanism proposed by Bychkov et al., and the mechanism of flame acceleration in channels with comb-like arrays of obstacles. 
  
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  Study of Asymmetric Lift-off Height of Ammonia-mixing Non-premixed Jet Flame Under Cross Airflow

  WANG Shaofei, TANG Fei, WANG Qiang, ZHENG Jingru, LÜ Jiang, HU Longhua

  Journal of Engineering Thermophysics. 2025, 46(8): 2782-2789.

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  Ammonia, as a zero-carbon renewable fuel, has significant potential for development in coping with energy crisis and climate change. Ammonia/hydrocarbon mixture fuels are more promising for applications by overcoming their disadvantages of low laminar flame speed and low reactivity compared to pure ammonia. The asymmetric lift-off height of an ammonia-doped nonpremixed jet flame under cross airflow was investigated using an experimental method. It is found that the lift-off height in the absence of cross airflow not only increases linearly with the fuel exit velocity, but also has a positive correlation with the ammonia mixing ratio. The variation of the lift-off heights of the windward and leeward sides of the flame with the wind speed was analyzed by the premixed flame theory, and it was found that the lift-off height of the leeward side was smaller than that of the windward side; and a lift-off height prediction model for the leeward side of the flame was proposed based on the ratio of the momentum of the fuel jet to that of the airflow.