无针注射设备作为一种新型流体机械成为医用水射流技术的研究重点，本研究旨在探究不同驱动压力模式下微射流的动力学特征。通过对比数值仿真与实验测试冲击压力结果，验证数值仿真模型的可靠性。进而通过数值仿真方法，分析不同驱动压力工况下喷嘴内外部流场分布特征，并探究驱动压力对微射流穿透扩散特征的影响规律。研究结果表明，不同驱动压力会影响喷嘴内部液流流态分布，驱动压力大于0.50 MPa 时会出现旋涡，且旋涡出现位置随驱动压力增大逐渐靠近收缩段。同时，两阶段驱动压力差和转换时间直接影响射流液柱形态，且双通道驱动压力模式下微射流在多孔介质中扩散更为均匀。因此，可通过调控双通道气压驱动特性来控制微射流动力学特征。

Needle-free injection devices have become the focus of research on medical water jet technology as a new type of fluid machinery. The aim of this study is to investigate the dynamic characteristics of the microjet under different driving pressure modes. By comparing the impact pressure results obtained from numerical simulations with experimental tests, the reliability of the numerical simulation model was validated. And then, the distribution characteristics of the flow field inside and outside the nozzle under different driving pressures are analyzed by numerical simulation. Finally, the influence of driving pressure on the penetration and diffusion characteristics of the microjet was investigated. The results show that different driving pressures affect the distribution of the liquid flow inside the nozzle, and a vortex will appear when the driving pressure is greater than 0.50 MPa, and the vortex location is close to the contraction section gradually with the increase of the driving pressure. At the same time, the driving pressure difference and conversion time between the two stages directly affects the morphology of the jet column. Also, compared with the single-channel pneumatic driving mode, the microjet generated from the dual-channel driving pressure mode has a more uniform diffusion pattern in the porous medium. Therefore, the microjet dynamics can be regulated by controlling the characteristics of dual-channel driving pressures.