Boundary Layer Effects behind Incident and Reflected Shock Waves in a Shock Tube

Introduction

In ideal shock tube experiments, flow properties behind the incident and reflected shock waves do not vary with distance or time, and can be calculated using the standard normal shock equations and the known incident shock speed. However, nonideal effects result in flow nonuniformity behind the incident shock wave, leading in turn to nonuniformity behind the reflected shock. It has been observed that behind the reflected shock, pressure typically increases gradually with time (positive dP5/dt) [1-3]. Such deviations of pressure (and concomitantly the temperature) from ideal values cause errors in chemical kinetic studies of rate coefficients and ignition delay times [2, 3]. Thus it is worthwhile to analyze nonideal shock tube effects and determine their impact on flow conditions, with a goal of improving experimental methods and gasdynamic models that will lead to more accurate experiments.