A simple, self-sufficient approach for the design of shock tube driver insert

Experimental data obtained in shock tubes, including ignition delay-time and species concentration profiles, are among the most significant parameters in combustion studies. Although shock tubes are widely considered as a quasi-ideal reactor for high-temperature studies, it involves a number of non-ideal effects such as a time-dependent pressure increase within the test section. This non-ideal pressure rise induces inaccuracy in the shock tube measurements. To overcome this issue, the driver insert strategy has proven to be successful. Nevertheless, the approaches presented in the literature to design such a driver insert either are not self-sufficient, i.e., they rely on external software, or lack flexibility. In this study, a simple, self-sufficient, fully analytical approach implemented in a MATLAB code has been developed to design a driver insert for the control of the rate of pressure rise in the test volume. The tip and end positions of the insert, as well as the effect of area change ratio on pressure behind reflected shock are obtained by the code. Extensive validation is performed against previous results from the literature and new data generated with several numerical codes.