Attenuation of Cavity Flow Oscillation Through Leading Edge Flow Control

Zhang, X.; Chen, X.X.; Rona, Aldo; Edwards, J. A.

doi:10.1006/jsvi.1998.2012

Cited by 37 publications

(11 citation statements)

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“…The flow field features boundary layer separation, shear layer instability, vortex flow, acoustics radiation, shock/expansion wave and shock-boundarylayer interactions, and self-sustained pressure oscillations. The co-presence of and interaction among these features in such a simple configuration and their potential hazardous effects on the performance, integrity, and stability of the vehicles present a challenging problem and have stimulated extensive experimental, analytical, 8,9,24,[37][38][39][40] and computational [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] investigations over the years. These studies largely concentrated on mean static-pressure distributions and/or unsteady-pressure spectra in cavities.…”

Section: Introductionmentioning

confidence: 99%

“…A variety of control methods have been tested and their effects on the cavity flow field documented. 1,9,31,36,54,55) Past researches have established that the defining parameter for these flows is their length-to-depth ratio (L/D). The effects of cavity width-to-length ratio (L/W ) were investigated by Ahuja and Mendoza, 28) Tracy and Plentovich, 30) Stallings and Wilcox, 2) et al Ahuja and Mendoza distinguished the cavity flow to be two-dimensional (2D) or three-dimensional (3D) depending on whether its L/W is less than or greater than 1.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation on the Mechanism of Flow-Type Changes in Supersonic Cavity Flows.

Zhang

Morishita

Okunuki

et al. 2002

Trans. Japan Soc. Aero. S Sci.

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Compressible flows over cavities with a series value of length-to-depth ratio (L/D) were investigated experimentally, with the objective being to elucidate the mechanism of the transition of types of cavity flows as their L/D increases or decreases. For open-type cavity flows, the freedom of backflow inside the cavity is found to be crucial in smoothing out adverse pressure gradient. The spreading of the shear layer and its gradual approach toward the cavity floor as L/D increases tend to suppress the freedom of backflow, causing the cavity flow to change from the open-type to the transitional-type. For closed-type cavity flows, the finite thickness of the upstream boundary layer leads to the presence of three kinds of characteristic lengths that correspond to the recirculation region, the deflection of the main flow and the recovery or the abrupt rise of the pressure, respectively. The compression fans at the foot of the impingement and the exit shock waves will approach each other well in advance of the possible merge of the vertices of the conventionally defined separation and recompression wakes. As the L/D of a closed cavity decreases, the reattached boundary layer on the mid-portion of the cavity floor will have less developing distance, thus it will be more susceptible to adverse pressure gradient and prone to separation. For the present two-dimensional cavity models, the critical values of L/D were found to be about 10 and 14 for the transition of cavity flows from the open-to the transitional-type and from the transitionalto the closed-type, respectively. The sum of the pressure lengths at the front and rear wakes agrees remarkably well with the second critical L/D.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on the Mechanism of Flow-Type Changes in Supersonic Cavity Flows.

Zhang

Morishita

Okunuki

et al. 2002

Trans. Japan Soc. Aero. S Sci.

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“…There are many passive actuators applied until now, such as sawtooth spoilers [5,18], static or oscillating fences [19,20], leadingand trailing-edge ramps [18,21], and rods [19,22]; and they have been proved efficient in disrupting the feedback loop and reducing cavity resonance. They come with limitations though, since they can only be effective under certain flow conditions and most of the time they have associated penalties of increased drag and/or weight.…”

Section: Introductionmentioning

confidence: 99%

Microjet Flow Control Effectiveness of Cavity Configurations at Low Speeds

Lada

Kontis

2014

Journal of Aircraft

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An experimental study was conducted to investigate the aeroacoustics of open-and closed-cavity configurations with and without flow control using microjets at low speeds. The cavity models had length-to-depth ratios of 2, 10, and 18, representing open, transitional, and closed cavities, respectively. The investigation was carried out at a flow speed of 16 meters per second. The microjet effectiveness was tested for jet velocities of 8, 16 and 24 meters per second. The vortex shedding aft of the trailing edge was reduced when the microjet velocity was equal to that of the freestream (16 meters per second). The results from the transitional cavity experiment, with a length-to-depth ratio of 10, showed that either higher microjet velocities or different locations of the microjets may be required to have any significant effect on the cavity flow characteristics. Nomenclature= voltage X c = measured distance from cavity leading edge X j = measured distance from center of jet δ = boundary-layer thickness (immediately upstream of the cavity opening) δ = boundary-layer displacement thickness (immediately upstream of the cavity opening) θ = boundary-layer momentum thickness (immediately upstream of the cavity opening) ρ ∞ = density

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“…Past experiments [3][4][5] and numerical studies 2,6 have tested a range of suppression strategies for cavity flows. These have included the use of ramps, [7][8][9][10][11] spoilers, rods 12 and air jets 4, 13, 14 located mainly on the upstream bulkhead, to affect the oncoming boundary layer approaching the enclosure. Some configurations considered ramps located at the downstream bulkhead, to alter the reattachment of the boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Control of Transonic Cavity Flow Instability by Streamwise Air Injection

Rona

2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

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A time-dependent numerical model of a turbulent Mach 1.5 flow over a rectangular cavity has been developed, to investigate suppression strategies for its natural self-sustained instability. This instability adversely affects the cavity form drag, it produces largeamplitude pressure oscillations in the enclosure and it is a source of far-field acoustic radiation.To suppress the natural flow instability, the leading edge of the two-dimensional cavity model is fitted with a simulated air jet that discharges in the downstream direction. The jet mass flow rate and nozzle depth are adjusted to attenuate the instability while minimising the control mass flow rate.The numerical predictions indicate that, at the selected inflow conditions, the configurations with the deepest nozzle (0.75 of the cavity depth) give the most attenuation of the modelled instability, which is dominated by the cavity second mode. The jet affects both the unsteady pressure field and the vorticity distribution inside the enclosure, which are, together, key determinants of the cavity leading instability mode amplitude. The unsteadiness of the pressure field is reduced by the lifting of the cavity shear layer at the rear end above the trailing edge. This disrupts the formation of upstream travelling feed-back pressure waves and the generation of far-field noise. The deep nozzle also promotes a downstream bulk flow in the enclosure, running from the upstream vertical wall to the downstream one. This flow attenuates the large-scale clockwise recirculation that is present in the unsuppressed cavity flow. The same flow alters the top shear layer vorticity thickness and probably affects the convective growth of the shear layer cavity second mode.

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Attenuation of Cavity Flow Oscillation Through Leading Edge Flow Control

Cited by 37 publications

References 0 publications

Experimental Investigation on the Mechanism of Flow-Type Changes in Supersonic Cavity Flows.

Experimental Investigation on the Mechanism of Flow-Type Changes in Supersonic Cavity Flows.

Microjet Flow Control Effectiveness of Cavity Configurations at Low Speeds

Control of Transonic Cavity Flow Instability by Streamwise Air Injection

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