Investigating the dominant factors regarding ignition transient in the design procedure of the nozzle of a pyrogen igniter

Yeşilyurt, Yavuz
In a standard solid rocket motor (SRM) system, the propellant of the SRM is generally ignited by a pyrotechnic device (which is much smaller in size compared to SRM itself). However, grand systems like solid propellant Space Propulsion Systems need more mass flow rate in a very short time duration to be ignited, which is not easy task for a pyrotechnic igniter. The solution for this issue is utilizing pyrogen igniter in the SRM system, which is both a small-scale SRM and an igniter. Here ignition transient becomes a very important design subject, because an extra element is added to the ignition train of the SRM system when a pyrogen igniter is used. In this thesis work, the nozzle design of pyrogen igniters is investigated and the most dominant factors that pressurize (therefore, accelerate ignition) the grand SRM propellant empty volume and shorten the ignition transient duration are determined by a design of experiment (DOE) procedure. The series of test case simulations is made by a “Fully Coupled Compressible Solver for Turbulent Perfect Gas Flows”, which is designed to solve closed volume problems like shock tube interactions, in a systematic and comparable manner. Before starting DOE procedure, the solver is validated by a test case having an exact solution. The importance and junction of parameters that should be considered in nozzle design of pyrogen igniters are discussed in the end of the thesis work.