Research of Two Phase 0-D Chamber Pressure Prediction Method for Solid Rocket Motor

In order to predict the chamber pressure of the metallized Solid Rocket Motors(SRMs) more accurately, the effect of two-phase nozzle flow was considered in the pressure calculation. The research begins from the solution of one-dimensional two-phase nozzle flow, and by the method of theoretical derivation and simplification, several theoretical models were proposed to solve the controlling equations. These models include two phase equilibrium flow model, two phase constant lag model, two phase isothermal model, and constant particle temperature model. Under each model, the total mass flow rate formulas of the gas-particle mixture in the nozzle were derived, as well as the zero-dimensional(0-D) chamber pressure formulas at the steady working state of the SRM. All the pressure formulas were used to calculate the chamber pressure of a metallized HTPB SRM and an aluminum-ice SRM, the results showed that when the propellant's metal content is high(like the HTPB SRM with 21% aluminum in the propellant), the traditional 0-D chamber pressure formula will lead to big errors, but by choosing a suitable two phase flow model and its corresponding chamber pressure calculation method, the errors can be reduced to less than 6% in the HTPB SRM. When the multi-dimensionnal(normally 2-D) numerical calculation method were used, the errors can be reduced to less than 2.5% in the HTPB SRM. It is concluded that in the calculation of chamber pressure in metallized SRMs, the two-phase-flow effect needs to be considered, and by the use of two phase corrected 0-D pressure prediction method, quicker and more accurate prediction results can be reached. © 2018, Editorial Department of Journal of Propulsion Technology. All right reserved.