Generalized Formulation to Predict Rossiter Modes for Subsonic to Hypersonic Flow
Jeremy P. Redding, Luis Bravo, Prashant Khare
TL;DR
This work addresses predicting Rossiter modes (Strouhal numbers) for flow over rectangular cavities from subsonic to hypersonic speeds without detailed a priori flow physics. It introduces a generalized, physics-based formulation derived from an Euler-based cavity feedback model and an energy-partition–driven effective temperature to compute the speed of sound, enabling accurate $St$ predictions. The Heller–Bliss correction diverges at high Mach numbers, while the proposed approach achieves agreement with DNS data within roughly $10\%$ and provides asymptotic $St$ limits, supported by two validation routes: a rapid bounding method and a four-regime temperature model. The methods offer practical guidance for predicting cavity acoustics across a wide Mach range, with implications for hypersonic design and aeroacoustic analysis, validated by two-dimensional DNS data.
Abstract
This paper describes the development of a generalized physics-based model to accurately estimate Rossiter modes for flow over rectangular cavities for regimes ranging from subsonic to hypersonic without the a priori knowlege of flow physics. The Heller-Bliss model is shown to diverge from direct numerical simulation (DNS) results, while the adapted model shows close alignment (within 10\%) with the DNS data at higher Mach numbers, and is physically reasoned on the basis of energy modes. Using an effective temperature to evaluate the speed of sound calculations and then using it to calculate the Strouhal number yields closer predictions to DNS data. The present work also establishes asymptotic limits for Strouhal numbers.