scholarly journals Local temperature perturbations of the boundary layer in the regime of free viscous–inviscid interaction

2012 ◽  
Vol 707 ◽  
pp. 595-605 ◽  
Author(s):  
M. V. Koroteev ◽  
I. I. Lipatov
Keyword(s):  
Boundary Layer ◽  
Numerical Solution ◽  
Local Heating ◽  
Separated Flow ◽  
Interaction Theory ◽  
Small Perturbations ◽  
Linear Problems ◽  
Free Interaction ◽  
Thermal Sources ◽  
Free Interaction Theory

AbstractWe analyse the disturbed flow in the subsonic laminar boundary layer, disturbances being generated by local heating elements, which are placed on the surface. It is exhibited that these flows are described in terms of free interaction theory for specific sizes of thermal sources. We construct the numerical solution for the case of a flat subsonic stream in the viscous asymptotic layer, in which the flow is described by nonlinear equations for vorticity, temperature and an interaction condition which provides the influence of perturbations to the pressure in the main order. The obtained solutions are compared with those for corresponding linear problems with small perturbations. It is demonstrated that strong temperature perturbations in some situations allow us to obtain the flow close to the separated flow.

Improvement of the free-interaction theory for shock wave/turbulent boundary layer interactions

2021 ◽  
Vol 33 (7) ◽  
pp. 075104
Author(s):  
Wen-Zhong Xie ◽  
Shu-Zi Yang ◽  
Cheng Zeng ◽  
Kai Liao ◽  
Run-Han Ding ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Turbulent Boundary Layer ◽  
Interaction Theory ◽  
Free Interaction ◽  
Free Interaction Theory

On the transition between regular and irregular shock patterns of shock-wave/boundary-layer interactions

2015 ◽  
Vol 776 ◽  
pp. 200-234 ◽  
Author(s):  
Jan Matheis ◽  
Stefan Hickel
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Deflection Angle ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Interaction Theory ◽  
Free Stream Mach Number ◽  
Free Interaction ◽  
Wave Boundary ◽  
Free Interaction Theory

The reflection of strong oblique shock waves at turbulent boundary layers is studied numerically and analytically. A particular emphasis is put on the transition between regular shock-wave/boundary-layer interaction (SWBLI) and Mach reflection (irregular SWBLI). The classical two- and three-shock theory and a generalised form of the free interaction theory are used for the analysis of well-resolved large-eddy simulations (LES) and for the derivation of stability criteria. We found that at a critical deflection angle across the incident shock wave, the perturbations related to the turbulent boundary layer cause bi-directional transition processes between regular and irregular shock patterns for a free-stream Mach number of$\mathit{Ma}_{0}=2$. Computational results show that the mean deflection angle across the separation shock is decoupled from the incident shock wave and can be accurately modelled by the generalised free interaction theory. On the basis of these observations, and the von Neumann and detachment criteria for the asymmetric intersection of shock waves, we derive the critical incident shock deflection angles at which the shock pattern may/must become irregular. Numerical data for a free-stream Mach number of$\mathit{Ma}_{0}=3$confirm the existence of the dual-solution domain predicted by theory.

Prediction of Massive Separation of Unstarted Inlet via Free-Interaction Theory

AIAA Journal ◽  
2015 ◽  
Vol 53 (4) ◽  
pp. 1108-1112 ◽  
Author(s):  
Wang Zhenguo ◽  
Zhao Yilong ◽  
Zhao Yuxin ◽  
Fan Xiaoqiang
Keyword(s):  
Interaction Theory ◽  
Free Interaction ◽  
Free Interaction Theory ◽  
Massive Separation

Characteristics of a separated flow past a semicircular leading-edge airfoil model under different imposed pressure gradient

2021 ◽  
pp. 095441002110212
Author(s):  
K Anand ◽  
KT Ganesh
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Pressure Gradient ◽  
Particle Image ◽  
Separation Bubble ◽  
Separated Flow ◽  
Leading Edge ◽  
Field Measurements ◽  
Bench Mark ◽  
Image Velocimetry

The effect of pressure gradient on a separated boundary layer past the leading edge of an airfoil model is studied experimentally using electronically scanned pressure (ESP) and particle image velocimetry (PIV) for a Reynolds number ( Re) of 25,000, based on leading-edge diameter ( D). The features of the boundary layer in the region of separation and its development past the reattachment location are examined for three cases of β (−30°, 0°, and +30°). The bubble parameters such as the onset of separation and transition and the reattachment location are identified from the averaged data obtained from pressure and velocity measurements. Surface pressure measurements obtained from ESP show a surge in wall static pressure for β = −30° (flap deflected up), while it goes down for β = +30° (flap deflected down) compared to the fundamental case, β = 0°. Particle image velocimetry results show that the roll up of the shear layer past the onset of separation is early for β = +30°, owing to higher amplification of background disturbances compared to β = 0° and −30°. Downstream to transition location, the instantaneous field measurements reveal a stretched, disoriented, and at instances bigger vortices for β = +30°, whereas a regular, periodically shed vortices, keeping their identity past the reattachment location, is observed for β = 0° and −30°. Above all, this study presents a new insight on the features of a separation bubble receiving a disturbance from the downstream end of the model, and these results may serve as a bench mark for future studies over an airfoil under similar environment.

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