Simulation and experimental study on the influence of needle-free jet injection nozzle structure on injection performance

Needle-free jet injection is an excellent alternative to conventional injection, which can reduce patients' fear of needle and needle injury and reduce the probability of cross contamination. It is highly appropriate for the administration of small doses of medicines, such as vaccines and insulin. The structure of the needle-free jet injector nozzle determines the properties of the jet, and the optimized nozzle can improve injection performance. This study used the realizable k-epsilon turbulence model to study the effects of different nozzle cone angles and nozzle lengths on the injection effect. The peak stagnation pressure, jet velocity, and peak turbulence intensity were selected as the primary research parameters. We achieved a better nozzle structure with further analysis, and experiments were performed to verify the accuracy of the simulation model. The simulation results show that in the five nozzles with different taper settings, the nozzle with a smaller taper has higher jet velocity and peak stagnation pressure at the nozzle orifice and within a specific taper range. On the contrary, the nozzle with a smaller taper has a lower jet velocity at 4 mm away from the nozzle orifice. The effect of the nozzle length on peak stagnation pressure is limited and shows no apparent law, while the effect on the turbulence intensity is evident. The longer the nozzle length is, the less turbulence intensity is. At the same time, we also studied the influence of different viscosity liquids and different elastic coefficients of the driving spring on the injection performance. The jet impact force experiment was carried out. The results show that the simulation results are highly consistent with the experimental results, which verify the accuracy of the CFD model. The results provide ideas for optimizing the nozzle structure of commercial needle-free jet injector and help realize efficient drug delivery.

Automated summary

Needle-free jet injection is a great alternative to conventional injection in reducing patients' fear of needles and needle-related injuries, as well as minimizing the risk of cross-contamination. This study utilized a realizable k-epsilon turbulence model to investigate the impact of different nozzle cone angles and lengths on injection performance. The simulation results were validated through experiments, showing that a smaller taper angle resulted in higher jet velocity and peak stagnation pressure within a specific range. Additionally, nozzle length had limited influence on peak stagnation pressure but had a noticeable effect on turbulence intensity. The findings provide insights for optimizing the nozzle structure of commercial needle-free jet injectors and achieving efficient drug delivery.