Flow Field Analysis and Structure Optimization of Large Dose Multi-Hole Needle-Free Injector

At present, the single-hole needle-free injector has a small injection dose and requires multiple injections. In order to solve the problem, a large-dose multi-hole needle-free injector is proposed in the paper. The workflow field of the single-hole needle-free injector was analyzed by ANSYS Workbench simulation platform, it is found that when the shrinkage angle is 20°and the length-diameter ratio is 1.4, the needle-free injector has better jet characteristics. Based on the simulation results, the orthogonal test was done to optimize the contraction section of the multi-hole needle-free injector. The optimized scheme was obtained as follows: the shrinkage angle of 20°, the length-diameter ratio of 1.4, the diameter of the distribution circle of 2mm, the contraction section length of 4.05mm and the diameter of the micro-hole of 0.165mm. Through the stress analysis of ampoule, it is verified that the optimized scheme can meet the mechanical property requirements of the material. The optimization results indicate that the injector has a larger dose than the conventional single-hole injector, which can reach 5 ml, and the injection velocity is more than 150 m/s, which can penetrate the skin without causing excessive damage. In this paper, the feasibility of the optimization scheme is further verified through the experiment.