Duration: 36 months
High frequency combustion instabilities (CI) hunt the development of new rocket engines. The coupling between acoustics, hydrodynamics and combustion leading to self-sustained pressure oscillations can destroy the engine. While they have been studied since decades, CI continue to be an issue for the development of new engines because there are no available tools able to predict if an engine will be stable or not. One of the major issue that limits the capability in developing stable engines is the multi-scale nature of the phenomenon. Perturbations arising at the injector level (few millmetres) can impact the behaviour of the overall system. Consequently, the analysis of the stability of the engine requires to handle the whole system including feed system, injectors, chamber and nozzle. The problem is strongly affected by the operative conditions. Particularly for reusable engines, requiring large thrust variations, it is necessary to assess the stability of the engine along all its mission. The only way today to assess the stability of the engine are full scale tests at the end of the development phase, that is too late. Europe is facing the need to accelerate the development process of new performant engines. The present project aims at filling one important need: develop fast and reliable tools able to assess the stability of a rocket engine in the preliminary design phases. The novelty of the proposed approach is to apply recent development in state space approaches to develop a low order tool to study transverse CI in liquid rocket engines. Large Eddy Simulations will be carried out in order to feed the low order model with appropriate flame response and injector dissipation models. Recent techniques involving AI for surrogate models based on high fidelity data will be used in order to obtained parametrised responses functions to feed the low order model.
