Propellant effects on SRM upper stage internal ballistics and performance with nozzle erosion characterization

Nozzle throat erosion is inherently present in high performance solid rocket motors because of high operative pressures and long combustion times. Whereas for large SRM boosters, operating in atmosphere, it does not represent a strong limit to obtain high performance, for upper stage SRMs it brings to relevant losses in the specific impulse and, hence, less effcient design of the solid rocket motor due to the nozzle throat erosion effects on both the operative pressure and specific impulse. This paper discusses the effects on the performance of an upper stage SRM of different kinds of aluminized propellants, compared to the baseline propellant HTPB 1912. The reference configuration is Zefiro 9A, third stage of the European launcher VEGA, recently qualified with its first maiden flight. The analysis is performed with the use of the complete coupling of the following models: a 3D grain burnback model, GREG, a full Navier-Stokes simulation of the nozzle throat erosion and a Q1D model of the SRM internal ballistic. © 2012 by E. Cavallini, D. Bianchi, B. Favini, M. Di Giacinto, F. Serraglia.