Study on Drug Powder Acceleration in a Micro Shock Tube

Abstract

Recently, needle-free drug delivery systems have been widely used for delivering drug particles into human body without any external needles in medical fields. Drug powders should be accelerated to obtain enough momentum to be delivered into the suitable layer of the skin. This is achieved by accelerating drug particles in a Contoured Shock Tube (CST) which consists of a micro shock tube and an expanded supersonic nozzle. Shock wave happens in micro shock tube, and supersonic flow with particles is induced by the shock wave and accelerated in the expanded nozzle. Even though micro shock tubes have been studied for a long time, detailed experimental data for shock waves and particle-gas flows are sparse to date and it is very important to investigate the complicated particle-gas flow fields for practical applications. In the present study, Particle Tracking Velocimetry (PTV) was used to measure the average velocity of the gas-particle flow behind the propagating shock wave. Unsteady flow properties and shock wave propagation were analyzed by this instantaneous particle velocity fields. Numerical simulation was performed with unsteady compressible Naver-stokes equations which were solved by using a fully implicit finite volume scheme. Discrete Phase Model (DPM) has been used for simulating particle-gas two-phase flows. Different particle diameter and density were performed in present numerical studies. Unsteady particle-gas flow characteristics and shock wave propagation have been studied and analyzed in details in present micro shock tube model.