Design and Implementation of a Driver Insert to Minimize Non-Ideal Pressure Rise in a High-Pressure Shock Tube

Shock tubes are widely used for high-temperature chemical kinetics studies due to their ability to generate near-instantaneous thermodynamic conditions behind reflected shock waves. However, non-ideal effects such as boundary-layer-induced shock attenuation and diaphragm-induced disturbances often result in a gradual pressure rise during the test time, compromising the accuracy of ignition delay measurements and species concentration data. This work aims to mitigate these effects by designing a custom driver insert for a high-pressure shock tube. The insert introduces a controlled area variation in the driver section to generate reflected expansion waves that counteract the unwanted pressure rise in the test section. The insert geometry is tailored to specific test times and target reflected shock conditions, with reference to methods previously established in literature. This effort serves as a foundation for future experiments involving laser absorption spectroscopy diagnostics in combustion environments. This paper outlines the theoretical basis, design methodology, and planned implementation of the insert, with the goal of enabling more accurate and extended-duration measurements in high-pressure shock tube facilities.