Injection parameters for an effective passive control of cavity flow instability

2002 ◽  
Author(s):  
A. Rona ◽  
E. Brooksbank
Keyword(s):  
Passive Control ◽  
Flow Instability ◽  
Cavity Flow ◽  
Injection Parameters

Effects of a Cavity Flow Passive Control on Optical Phase Degradations

2005 ◽  
Author(s):  
R. Deron ◽  
H. Illy ◽  
P. Geffroy ◽  
F. Mendez ◽  
B. Corbel
Keyword(s):  
Passive Control ◽  
Cavity Flow ◽  
Optical Phase

scholarly journals Effects of Active and Passive Control Techniques on Mach 1.5 Cavity Flow Dynamics

2017 ◽  
Vol 2017 ◽  
pp. 1-24
Author(s):  
Selin Aradag ◽  
Kubra Asena Gelisli ◽  
Elcin Ceren Yaldir
Keyword(s):  
Passive Control ◽  
Control Method ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Cavity Flow ◽  
Flow Dynamics ◽  
Cover Plate ◽  
Control Methods ◽  
Trailing Edge ◽  
Control Techniques

Supersonic flow over cavities has been of interest since 1960s because cavities represent the bomb bays of aircraft. The flow is transient, turbulent, and complicated. Pressure fluctuations inside the cavity can impede successful weapon release. The objective of this study is to use active and passive control methods on supersonic cavity flow numerically to decrease or eliminate pressure oscillations. Jet blowing at several locations on the front and aft walls of the cavity configuration is used as an active control method. Several techniques are used for passive control including using a cover plate to separate the flow dynamics inside and outside of the cavity, trailing edge wall modifications, such as inclination of the trailing edge, and providing curvature to the trailing edge wall. The results of active and passive control techniques are compared with the baseline case in terms of pressure fluctuations, sound pressure levels at the leading edge, trailing edge walls, and cavity floor and in terms of formation of the flow structures and the results are presented. It is observed from the results that modification of the trailing edge wall is the most effective of the control methods tested leading to up to 40 dB reductions in cavity tones.

416 Passive Control of Supersonic Cavity Flow Using Sub-Cavity(2)

2007 ◽  
Vol 2007 (0) ◽  
pp. _416-1_-_416-4_
Author(s):  
Shigeru MATSUO ◽  
Kenbu TERAMOTO ◽  
Shinya NAKANO ◽  
Toshiaki SETOGUCHI
Keyword(s):  
Passive Control ◽  
Cavity Flow ◽  
Supersonic Cavity

scholarly journals Control of a purely elastic symmetry-breaking flow instability in cross-slot geometries

2019 ◽  
Vol 881 ◽  
pp. 1123-1157 ◽  
Author(s):  
Mahdi Davoodi ◽  
Allysson F. Domingues ◽  
Robert J. Poole
Keyword(s):  
Symmetry Breaking ◽  
Stagnation Point ◽  
Passive Control ◽  
Flow Instability ◽  
Extensional Flow ◽  
Creeping Flow ◽  
Viscous Force ◽  
Benchmark Problems ◽  
Blockage Ratio ◽  
The Cross

The cross-slot stagnation point flow is one of the benchmark problems in non-Newtonian fluid mechanics as it allows large strains to develop and can therefore be used for extensional rheometry measurements or, once instability arises, as a mixing device. In such a flow, beyond a critical value for which the ratio of elastic force to viscous force is high enough, elasticity can break symmetry even in the absence of significant inertial forces (i.e. creeping flow), which is an unwanted phenomenon if the device is to be used as a rheometer but beneficial from a mixing perspective. In this work, a passive control mechanism is introduced to the cross-slot by adding a cylinder at the geometric centre to replace the ‘free’ stagnation point with ‘pinned’ stagnation points at the surface of the cylinder. In the current modified geometry, effects of the blockage ratio (the ratio of the diameter of the cylinder to the width of the channel), the Weissenberg number (the ratio of elastic forces to viscous forces) and extensibility parameters ($\unicode[STIX]{x1D6FC}$ and $L^{2}$) are investigated in two-dimensional numerical simulations using both the simplified Phan-Thien and Tanner and finitely extensible nonlinear elastic models. It is shown that the blockage ratio for fixed solvent-to-total-viscosity ratio has a stabilizing effect on the associated symmetry-breaking instability. The resulting data show that the suggested modification, although significantly changing the flow distribution in the region near the stagnation point, does not change the nature of the symmetry-breaking instability or, for low blockage ratio, the critical condition for onset. Using both numerical and physical experiments coupled with a supporting theoretical analysis, we conclude that this instability cannot therefore be solely related to the extensional flow near the stagnation point but it is more likely related to streamline curvature and the high deformation rates towards the corners, i.e. a classic ‘curved streamlines’ purely elastic instability. Our work also suggests that the proposed geometric modification can be an effective approach for enabling higher flow rates to be achieved whilst retaining steady symmetric flow.

416 Passive Control of Supersonic Cavity Flow Using Sub-Cavity(1)

2007 ◽  
Vol 2007 (0) ◽  
pp. _416-a_
Author(s):  
Shigeru MATSUO ◽  
Kenbu TERAMOTO ◽  
Shinya NAKANO ◽  
Toshiaki SETOGUCHI
Keyword(s):  
Passive Control ◽  
Cavity Flow ◽  
Supersonic Cavity
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