Transient Induced Delay in the Check Injector of the ADDA Combined Rocket Motor

Abstract

Conceived as simple, cheap and highly efficient alternative to solid rocket motors, the compound rocket engines include a liquid feed line system, within which at least the minimal components are involved, like the liquid tank, the dislocation augmenter, the main release valve, the in-line check valve (ICV) and the injector head. Simplicity and reliability are the main requirements in designing and manufacturing the components and, in order to accomplish these requirements, the dynamics and transient behavior of the devices become the key features of the entire design. The transient of the ICV required primary attention as it needs to cut the reversed flow of the liquid in a definitely short amount of time, determined from the condition of a given liquid return delay stop into the internal feed duct (IFD) of the engine. This delay was also set to cover the condition of partial vaporization of the liquid within the ICV and the IFD of the system. Numerical simulations were performed under rational assumptions regarding the mechanical behavior of ICV parts, limited to a number of minimal elements that secure a smooth work of the device and a fast response to upwind and downwind liquid pressure variations. The basic parameters considered are the size of the parts, their densities, closely connected to the manufacturing materials involved, sealing and surface finishing technology used that outputs the viscous and friction properties of the device parts considered for simulation. The ORVEAL research is granted by Romanian UEFISCDI.