CHARACTERIZATION OF THE INFLUENCE OF MODERATE PRESSURE FLUCTUATIONS ON THE COOLING PERFORMANCE OF ADVANCED COMBUSTOR COOLING CONCEPTS IN A REACTING FLOW

摘要

Lean low emission combustors are prone to combustion instabilities. Therefore integrating damping devices into the cooling concept is a viable approach. Information on the impact of pressure fluctuations caused by combustion instabilities on the cooling performance of both acoustic-focused and cooling-optimized concepts is required to support the decision regarding the cooling and damping strategy. In this contribution the effect of pressure fluctuations on different double skin cooling concepts in a realistic environment is presented. Pressure oscillations reduce the cooling effectiveness especially at low cooling air pressure drops. Here the cooling effectiveness of a more cooling optimized sample is affected most by the pressure oscillations. The cooling effectiveness of samples with a low thermal conductivity is more affected by the pressure fluctuations. Due to the low pressure drop across the hot gas wall and the perpendicular holes damping focused cooling concepts are prone to film fluid flowing back into the cavity during the pressure maximum of the oscillation. Together with the results the experimental approach is described and emphasis is laid on the adaption and validation of the measuring technique.