Simulation of Combustion Instabilities in Liquid Rocket Engines with Acoustic Perturbation Equations

The authors present a new method for predicting combustion instabilities in liquid rocket engines. This method is based on the solution of the linearized governing equations for a three-dimensional combustor geometry in the time domain. The aim of this paper is to show the general feasibility of the approach and to explain the general behavior of the model. The computational domain comprises the combustion chamber itself and the convergent part of the nozzle. The heat release is included via a source term in the linearized energy equation. In the example of the European Aestus engine, it is shown that the model is able to predict the different oscillation modes without any preliminary assumptions about them. An analysis of the influence of the nozzle illustrates that its behavior is automatically included in the approach by design. In comparison to the solution of the full Navier-Stokes equations, the method has the advantage of a much lower numerical cost.