Fluid Mechanics Analysis of a Voice Coil Needle Free Jet Injector

Abstract

This paper considers the analytic modelling of the voice coil actuated needle free jet injection. It first investigates the currently existing model for the injection and making some alterations based on the system behavior and basic definitions in physics. These alterations yielded a new set of equations which were solved using the Runge-Kutta-Felberg formular. Second order, forth order and fifth order curve fitting of the numerical model were performed in order to develop a polynomial that gives the direct non-differential pressure-time relationship for the needle free jet injection (developed, to the best knowledge of the authors, for the first time). This fifth order polynomial presented the least error, measured by the least of the norm of residuals. The model for the voice coil activator was developed by writing force balance equations based on Newton’s second law of motion. The transfer function of the motor was then used to investigate the behavior of the voice coil actuator. Finally, the two systems (voice coil motor and injection) were linked up by setting up an analogous electromechanical system to see the behavior of the voice coil motor in the injection. Where the mechanical parts represent the injection pressure profile.

Keywords: Needle Free Jet Injection, Voice coil motor