Prediction of Pyroshock-Reduced Separation Nut Behaviors

Abstract

In this work, an efficient model is proposed to predict the complicated coupling behavior of a pyroshock-reduced separation nut, which has two variable-volume chambers connected by the vent hole. The model considers the effect of mutual interactions between combustion products and internal moving parts of the separation nut. To accomplish this, governing equations for combustion modeling are systematically derived, assuming that the flowfield within each chamber is homogeneous. For internal moving parts of the separation nut, the equations of motion are constructed. The equations are used to construct a coupled model. The behavior of the model from solving the system of differential equations is obtained, based on the Dormand–Prince embedded Runge–Kutta method. To validate the model, its behavior is compared with the test results of an actual prototype. Furthermore, modeling effects of the condensed phase product and initial air are investigated, and their significance in combustion modeling is identified. Parametric studies are then carried out to investigate the effects of the design parameters on the separation behavior. The results indicate that the model could be used efficiently in the design of separation nuts.