Thermomechanical Analysis and Optimization of Cryogenic Liquid Rocket Engines

Abstract

A coupled finite element fluid-structure interaction analysis of regeneratively cooled rocket combustion chambers, which allows the computation of the coolant flow and the heat conduction between the coolant and the combustion chamber structure, is presented. Furthermore, the resulting elasto-plastic deformation of the combustion chamber under cyclic thermal and mechanical loading is analyzed. The developed solution strategy is applied to the prediction of the heat transfer and thermomechanical load-induced deformation process of the European rocket engine Vulcain. Based on the results, the failure mechanism of the combustion chamber and its governing parameters are identified. It is demonstrated that this mechanism significantly reduces the lifetime of the rocket engine. Besides the conceptual design by the engineer, a mathematical optimization procedure based on the finite element model of the combustion chamber is investigated. This optimization method allows the improvement of an initial design with respect to a finite number of design variables such that the stress, plastic strain, or temperature levels are decreased, and accordingly. the lifetime will be increased.