Experimental study on gas-particle two-phase flows in a micro shock tube

Recently, micro shock tubes have been widely used in various fields such as aerospace, combustion and medical science. Needle-free drug delivery device is a typical example of the application of the micro shock tube used in the field of medical science. Compared to the macro shock tube, the flow viscosity and micro scale effects considerably influence the shock wave propagation in the micro shock tube, which makes shock wave behaviors significant difference from the theoretical prediction. Boundary layers which develop behind the moving shock wave attenuate the shock wave propagation as well. Additionally, the gas-particle flows are also shown the different characteristics compared to the single gas flow in the micro shock tube. Particles are induced by the shock wave inside the micro shock tube and accelerated in the supersonic nozzle. Supersonic flows and particle velocity make experimental studies difficult to be performed in the micro shock tube. Even though micro shock tubes have been studied for decades, shock flow characteristics and particle dynamics inside the micro shock tube are not well known to date. For the present study, pressure measurements and optical visualization have been carried out in a micro shock tube. Static pressure measurements were used for investigating the shock wave propagation in the driven section, and Pitot pressure measurements were used for obtaining flow characteristics at the exit of nozzles. Two high sensitive pressure transducers were used for recording pressure changes as the shock wave moved through pressure transducers and the shock Mach number was calculated. Particle tracking velocimetry was conducted to analyze particle-gas two-phase flows. Particle distribution and velocity were obtained in the present experiment study.