Shear layer resonance over open cavities at angles to the flow direction

Bari, Abdullahel; Chambers, F. W.

doi:10.2514/6.1993-4397

Cited by 4 publications

(1 citation statement)

References 12 publications

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“…Savory [10] showed that the most asymmetric flow pattern inside a cavity and the lowest drag occur at = 45 ∘ for L/H = 6-16. In terms of self-sustained oscillations, Bari and Chambers ( ∞ = 20-44 m/s) [11] showed that the yaw angle for a cavity need not significantly affect the resonant frequencies. However, there may be a switch in the dominant mode and the effective stream-wise length, / cos( ), of a cavity at yaw is probably not a suitable characteristic length.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Yaw Angle on a Compressible Rectangular Cavity Flow

Lee

Chung

Chang

2017

International Journal of Aerospace Engineering

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Experiments are performed to determine the characteristics of a compressible flow over yawed rectangular cavities for Mach numbers of 0.64, 0.70, and 0.83. The cavity's length-to-depth ratio varies from 4.43 to 21.50 and the length-to-width ratio is unity. The yaw angle is 0 ∘ -45 ∘ . The upstream compression and downstream expansion near the front and rear corners of a cavity decrease when the value of the yaw angle increases. The amplitude of the fluctuating pressure is a maximum for an open cavity with a yaw angle of 15∘ . An increase in the yaw angle results in a reduction in the pressure fluctuations for both open and transitional cavities. In the span-wise direction, variations in the mean and fluctuating pressure are less significant than those in the chord-wise direction. The oscillating frequency of resonance varies slightly with the yaw angle, but the amplitudes for the power spectral density are significantly reduced when the yaw angle is larger than 30 ∘ . For lower Mach numbers, the lower mode plays an important role in self-sustained oscillations for an open cavity when there is an increase in the yaw angle.

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Section: Introductionmentioning

confidence: 99%

The Effect of Yaw Angle on a Compressible Rectangular Cavity Flow

Lee

Chung

Chang

2017

International Journal of Aerospace Engineering

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Flow regimes associated with yawed rectangular cavities

et al. 2001

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The present work is concerned with the aerodynamics of the turbulent boundary-layer flow over yawed rectangular cavities with the focus on the steady and unsteady pressures generated by the interaction. Cavities with a planform aspect ratio of 4-85 and streamwise length to depth ratios from 1 to 3 were studied experimentally in a low-speed wind tunnel. The results indicated three main types of cavity flows. The shear layer bridges the cavity for small angles between mean flow direction and minor cavity axis. The flow field remains almost two-dimensional with little change in drag coefficient. Strong instabilities, associated with a rise in drag coefficient, are found when the cavity is yawed to greater angles. An aerodynamic feedback mechanism depending on interactions between the separated shear layer and the cavity fluid is suggested as the mechanism responsible for the generated oscillations. The influence of the cavity depth is, hereby, found to be fundamental as it determines the degree to which interactions between the separated shear layer and the cavity base occur. As a result both the magnitude and the frequency of the instabilities are a function of the cavity depth. When rotating to higher angles a greater portion of the shear layer reattaches to the cavity base which leads to a loss of flow organisation and a significant increase in drag.

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