Abstract in English:

A novel technique is presented to improve the initialization of compressible combustion LES, DNS or URANS by numerically turning the flame into a damper to quickly remove (artificial) pressure fluctuations and acoustic energy from the system. This is achieved by modifying the pressure dependency of the heat release rate, effectively modifying the Rayleigh Integral to achieve negative values, so that the acoustic energy is quickly removed from the system. The technique can (a) reduce the cost of simulations (by shortening the initialization), (b) contribute to stabilize the simulation, (c) help to avoid unrealistic thermoacoustic modes and, (d) potentially, be modified to compensate for excessive numerical dissipation of acoustic energy. Examples from LES of a thermoacoustic test case are presented to demonstrate the effective stabilization achieved.