Entropy-Patch-Choked-Nozzle Interaction: Quasi-Steady-Modeling-Regime Limits Probed
K. Kowalski (University of Twente)
S.J. Hulshoff (TU Delft - Aerodynamics)
P. Ströer (University of Twente)
Jan Withag (University of Twente)
A. Genot (ONERA Centre de Toulouse)
A. S. Morgans (Imperial College London)
F. Bake (Bundesanstalt für Materialforschung und -prüfung (BAM))
K. Venner (University of Twente)
Martinus P.J. Sanders (University of Twente)
L. Hirschberg (University of Twente)
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Abstract
Indirect combustion noise due to the interaction of flow inhomogeneities with a choked combustion-chamber exit is an important cause of combustion instability in solid rocket motors. Moreover, it is believed to be an issue in electrical-power generation turbines and aero-engines. If these flow inhomogeneities are essentially characterized by the fluid having a locally appreciably-different thermodynamic state, the acoustic response engendered by its interaction with the combustion-chamber exit is commonly referred to as entropy noise. In this paper, dedicated numerical-simulation results of entropy-patch choked-nozzle interactions are presented. Two types of entropy patches were considered: rectangular slugs and circular spots. Moreover, analytical-model-based analysis, of said simulation results, is presented. Based on said analysis, the authors posit the existence of three modeling regimes: the quasi-steady-modeling regime, the blended-physical-effects regime, and the inertial-modeling regime.