Large-eddy simulations of supersonic cavity flowfields are performed using a high-order numerical method. Spatial derivatives are represented by a fourth-order compact approximation that is used in conjunction with a sixth-order nondispersive filter. The scheme employs a time-implicit approximately factored finite difference algorithm, and applies Newton-like subiterations to achieve second-order temporal and fourth-order spatial accuracy. The Smagorinsky dynamic subgrid-scale model is incorporated in the simulations to account for the spatially underresolved stresses. Computations at a freestream Mach number of 1.19 are carried out for a rectangular cavity having a length-to-depth ratio of 5:1. The computational domain is described by 2.06×10 7 grid points and has been partitioned into 254 zones, which were distributed on individual processors of a massively parallel computing platform. Active flow control is applied through pulsed mass injection at a very high frequency, thereby suppressing resonant acoustic oscillatory modes

Large-Eddy Simulation of Supersonic Cavity Flowfields Including Flow Control

Review of numerical simulations for high-speed, turbulent cavity flows

https://acoustique.ec-lyon.fr/publi/gloerfelt_jsv03.pdf

Direct computation of the noise radiated by a subsonic cavity flow and application of integral methods

Flow-induced cavity resonance is characterized by large amplitude tones in and around the cavity. While passive suppression techniques can be optimized for a single operating condition, their performance often degrades at offdesign conditions. Active control is attractive because of its potential to adapt to different operating conditions without significant performance degradation. This paper describes an investigation of active control of flow-induced cavity resonance at low Mach numbers. Attention is focused on a deep (Z/D=0.5) and a shallow cavity (L/D=2.0). For the uncontrolled cases studied, the evidence indicates that the tones generated by low Mach number flow over a cavity are the result of an interaction between the forced acoustic response of the cavity and the amplification of feedback disturbances by the shear layer. Active control is accomplished with piezoelectric actuators implemented as an active, segmented flap at the upstream separation edge. Both open- and closed-loop control suppress the tone associated with the flow-induced resonance, resulting in SPL reductions of up to 20 dB. However, the closed-loop control requires one order-of-magnitude less power. In both cases, the mean shear-layer velocity profile is unaffected by the control input, while the velocity fluctuations undergo significant changes.

Active Control of Flow-Induced Cavity Resonance

Cavities are widely used as flameholders in supersonic combustors due to their outstanding potential to stabilize combustion without excessive total pressure loss. A review of cavity-stabilized combustion for scramjet applications is provided in this article. The topics cover the fundamental problems and recent advances regarding cavity-organized combustion in high-speed flows, including combustion stabilization modes and mechanisms, flame stability analyses and correlations, combustion oscillations, and other related issues. Remarkable questions such as cavity-coupled fuel injection, flow and combustion coupling, optimal cavity geometry and scale, auto-ignition and flame propagation interactions, and unsteady effects are discussed. Then, an attempt is made to provide some guidelines for the future research of cavity flameholders.

Review of cavity-stabilized combustion for scramjet applications:

A time-accurate double thin-layer Navier-Stokes computation is performed for an unsteady supersonic open cavity with a length-to-depth ratio of 2 The results are used to determine the flow-physics mechanisms responsible for the cavity oscillation cycle A new cycle is described and compared to previous descriptions It is found that a shed vortex impinges on the cavity aft lip and forms a pressure pulse that augments or forces, at the vortex shedding frequency, an internal upstream moving wave that has been reflected from the aft corner This upstream moving wave eventually reflects off the cavity forward wall and forces the shedding of a new vortex It was found, however, that the reflected wave dissipates before it reaches the aft wall Instead, a second wave forms beneath the shed vortex and eventually reflects from the aft corner and is forced at the shedding frequency by the shed vortex wave, completing the cycle

Algebraic turbulence model simulations of supersonic open-cavity flow physics

A study of several modified versions of the Baldwin-Lomax turbulence model applied to two-dimensional supersonic open cavity flowfields are performed. The results are clearly affected by the levels of turbulent viscosity imposed in the cavity.

Chung-Jen Tam

Papers

Algebraic turbulence model simulations of supersonic open-cavity flow physics

Comparison of Baldwin-Lomax Turbulence Models for Two-Dimensional Open Cavity Computations

Supersonic open cavity flow physics ascertained from algebraic turbulence model simulations

A comparison of several standard turbulence models for 2-D open cavity flow field computations

Observations on using experimental data as boundary conditions for computations