Entropy-Patch Choked-Nozzle Interaction: Effects of Nozzle Convergent Geometry on Scaled Upstream Acoustic Response

Abstract

Elbakly et al. [Elbakly, K., Hulshoff, S. J., Olivon, F., Genot, A., Bake, F., Venner, C. H., and Hirschberg, L., “Entropy-patch choked-nozzle interaction: quasi-steady and inertial modeling regimes mapped and limits of linearization established,” 32nd AIAA/CEAS Aeroacoustics Conference (2026), American Institute of Aeronautics and Astronautics, 2026] established for a fixed nozzle geometry the existence of two linear modeling regimes for entropy-patch choked-nozzle interaction noise; viz., the essentially unsteady inertial & quasi-steady matching-condition modeling regimes. Here, a study is presented that sought to elucidate the influence the choked nozzle convergent section's geometry on the acoustic response generated due to the interaction of an entropy block (rectangular slug-like entropy patch) with a choked nozzle. Four dimensionless geometric parameters which affect sound production were identified: the nozzle-inlet length ratio, the degree of the nozzle, the contraction ratio and the quasi-1D parameter. State-of-the-art numerical simulation code based ceteris paribus parameter studies were carried out and used to further establish the limits of the inertial & matching-condition modeling regimes.