On linear instability mechanisms in incompressible open cavity flow

AbstractA theoretical study of linear global instability of incompressible flow over a rectangular spanwise-periodic open cavity in an unconfined domain is presented. Comparisons with the limited number of results available in the literature are shown. Subsequently, the parameter space is scanned in a systematic manner, varying Reynolds number, incoming boundary-layer thickness and length-to-depth aspect ratio. This permits documenting the neutral curves and leading eigenmode characteristics of this flow. Correlations constructed using the results obtained collapse all available theoretical data on the three-dimensional instabilities.

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Global instability analysis and control of three-dimensional long open cavity flow

10.20868/upm.thesis.39444 ◽

2016 ◽

Author(s):

Qiong Liu

Keyword(s):

Three Dimensional ◽

Cavity Flow ◽

Open Cavity ◽

Global Instability ◽

Instability Analysis ◽

And Control

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EFFECTS OF BOUNDARY-LAYER THICKNESS ON UNSTEADY FLOW CHARACTERISTICS INSIDE OPEN CAVITIES AT SUBSONIC AND TRANSONIC SPEEDS

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194512008768 ◽

2012 ◽

Vol 19 ◽

pp. 206-213

Author(s):

DANG-GUO YANG ◽

JIAN-QIANG LI ◽

ZHAO-LIN FAN ◽

XIN-FU LUO

Keyword(s):

Boundary Layer ◽

Unsteady Flow ◽

Layer Thickness ◽

Boundary Layer Thickness ◽

Sound Pressure ◽

Flow Characteristics ◽

Open Cavity ◽

Aerodynamic Noise ◽

Sustained Oscillation ◽

Cavity Depth

An experimental study was conducted in a 0.6m by 0.6m wind-tunnel to analyze effects of boundary-layer thickness on unsteady flow characteristics inside a rectangular open cavity at subsonic and transonic speeds. The sound pressure level (SPL) distributions at the centerline of the cavity floor and Sound pressure frequency spectrum (SPFS) characteristics on some measurement positions presented herein was obtained with cavity length-to-depth ratio (L/D) of 8 over Mach numbers (Ma) of 0.6 and 1.2 at a Reynolds numbers (Re) of 1.23 × 107 and 2.02 × 107 per meter under different boundary-layer thickness to cavity-depth ratios (δ/D). The experimental angle of attack, yawing and rolling angles were 0°. The results indicate that decrease in δ/D leads to severe flow separation and unsteady pressure fluctuation, which induces increase in SPL at same measurement points inside the cavity at Ma of 0.6. At Ma of 1.2, decrease in δ/D results in enhancing compressible waves. Generally, decrease in δ/D induces more flow self-sustained oscillation frequencies. It also makes severer aerodynamic noise inside the open cavity.

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Experimental and theoretical study of swept-wing boundary-layer instabilities. Three-dimensional Tollmien-Schlichting instability

Physics of Fluids ◽

10.1063/1.5125812 ◽

2019 ◽

Vol 31 (11) ◽

pp. 114104

Author(s):

V. I. Borodulin ◽

A. V. Ivanov ◽

Y. S. Kachanov ◽

D. A. Mischenko ◽

R. Örlü ◽

...

Keyword(s):

Boundary Layer ◽

Theoretical Study ◽

Three Dimensional ◽

Swept Wing ◽

Tollmien Schlichting

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Secondary Losses in a Large Deflection Annular Turbine Cascade: Effect of the Entry Boundary Layer Thickness

Volume 1: Turbomachinery ◽

10.1115/86-gt-171 ◽

1986 ◽

Author(s):

M. Govardhan ◽

N. Venkatrayulu ◽

D. Prithvi Raj

Keyword(s):

Boundary Layer ◽

Layer Thickness ◽

Boundary Layer Thickness ◽

Three Dimensional ◽

Secondary Flows ◽

Impulse Turbine ◽

Flow Measurements ◽

Local Loss ◽

Trailing Edges ◽

Annular Cascade

The paper presents the results of three dimensional flow measurements behind the trailing edges of an impulse turbine blade row of 120° deflection in an annular cascade. The entry boundary layer thickness was systematically varied on the hub and casing walls separately and its effect on secondary flows and losses is investigated. With the increase of entry boundary layer thickness, it has been found that (i) the contours of local loss coefficient show that the magnitude of the hub loss core increased, (ii) the loss cores near the hub and casing wall are convected away from the walls, (iii) the spanwise variation of the pitchwise averaged losses indicate that the position of large loss peak near the hub wall remains the same, but the magnitude of the loss increases, (iv) the exit static pressure increases and the exit velocity in general decreases, (v) the degree of underturning of flow increases and (vi) the net secondary losses do not change appreciably.

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