The Impact of Steady Blowing from the Leading Edge of an Open Cavity Flow

Abstract

Cavity flows occur in a wide range of low-speed applications (Mach number ≤0.3), such as aircraft wheel wells, ground transportation, and pipelines. In the current study, a steady jet is forced from a cavity leading edge at different momentum fluxes (0.11 kg/ms2, 0.44 kg/m·s2, and 0.96 kg/m·s2). The investigation was performed for an open cavity with length to depth ratio of 4 at the Reynolds number based on a cavity depth of approximately 50,000. Particle image velocimetry, surface oil flow visualisation, constant temperature anemometry, and pressure measurements were performed in this investigation. The aim of the jet blowing is to separate the cavity separated shear layer from the recirculation zone to reduce the cavity return flow, and hence stabilise the cavity separated shear layer. It was found that increasing the jet momentum flux causes an increase in the cavity return flow due to the increase in the thickness of the cavity separated shear layer. The study also found that the jet populates the separated shear layer with a large number of small-scale disturbances. These disturbances increase the broad band level of the pressure power spectra and Reynolds shear stress in the cavity separated shear layer. On the other hand, the jet disturbances make the shedding of the large vortical structures more intermittent.

Experimental Research on Reducing Flow-Induced Cavity Resonance with a Narrowband Active Noise Control System

“…Among them, the most common method is active flow control, in which leading-edge actuators are usually used to regulate the flow field on the opening surface of the cavity, so that both the flow oscillations and acoustic resonance could be reduced. It has been reported by recent works that using plasma actuators [10,11] as well as injecting extra flows [12][13][14] at the leading edge could effectively suppress the cavity resonance noise. Lu et al [15][16][17] developed the surface perturbation technique, in which a piezo actuator was designed and installed upstream in a duct system so that the resonance noise of the downstream side-wall cavity could be reduced.…”

“…Leclercq et al [18] also presented a closed-loop control method, where a series of linear controllers are iteratively designed to control the nonlinear oscillations of resonating flows. Although different methods of active flow control have been confirmed to be effective to suppress the cavity resonance noise, an obvious drawback of such methods is that the noise level at other frequencies would possibly be enhanced, as could be observed in [10][11][12][13][14][15][16][17][18].…”

Orthogonal optimization for effective classification of different tea leaves by a novel pressure stabilized inclined chamber classifier

“…Low‐speed flow in the cavity is widely used. Haddabi et al (2021) studied that under different momentum fluxes, the jet forcibly generates a steady jet from the front edge of the cavity. The purpose of the jet is to separate the cavity separation shear layer from the recirculation zone, so as to reduce the cavity backflow and stabilize the cavity separation shear layer.…”