Unsteady High-Order Simulation of a Liquid Oxygen/Gaseous Hydrogen Rocket Combustor

摘要

Coupled Euler-Lagrange simulations are performed for a subcritically operated model rocket combustor at 10 bar pressure (MASCOTTE A-10 test case). A Lagrangian spray model is used to simulate the liquid phase. This liquid oxygen/gaseous hydrogen single element combustor experiment has been the focus of many numerical studies. In contrast to previous investigations, time-accurate unsteady Reynolds-averaged Navier-Stokes simulations are performed. A good spatial resolution is achieved by using a fifth-order multidimensional limiting process scheme to discretize the inviscid fluxes. Instead of assuming axisymmetry, the three-dimensional geometry of the rectangular combustor is taken into account. However, only a quarter of the combustor is simulated, to limit the computational cost. Presented results indicate that three-dimensional effects are important, questioning the assumption of axisymmetry. A second important finding is that time-averaged unsteady Reynolds-averaged Navier-Stokes results agree much better with experimental data than those of a comparable steady-state simulation. Close to the injector, results show a strong unsteadiness of the turbulent flame, which has been observed in the experiment, too. Finally, pressure fluctuations are monitored at several positions in the combustor and analyzed by fast Fourier transform. The peak amplitudes in the pressure spectra could successfully be assigned to the first longitudinal acoustic mode and its higher harmonics.