Effects of Unsteady Heat Release on Liquid Rocket Combustion Instability

Abstract

Combustion instability is the leading technical risk for liquid rocket development efforts. However, the influence of unsteady combustion and distributed heat release on this phenomenon has been unclear. To address this open question, the heat release linear growth rate equation from the Universal Combustion Device Stability™ (UCDS™) Process was exercised with a simple combustion model. The initial results are presented, including relationships for steady and unsteady temperature and heat release. These results are then integrated to generate the linear growth rate for a range of frequencies. When fully developed and implemented, the approach described in this paper will clearly show the contribution of unsteady combustion to combustion instability.