scholarly journals Influence of leading-edge curvature on excited unsteady cross-flow vortices in three-dimensional boundary-layer

2018 ◽  
Vol 67 (21) ◽  
pp. 214702
Author(s):  
Lu Chang-Gen ◽  
Shen Lu-Yu
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Cross Flow ◽  
Leading Edge ◽  
Dimensional Boundary

Three-dimensional boundary-layer instability and separation induced by small-amplitude streamwise vorticity in the upstream flow

1993 ◽  
Vol 246 ◽  
pp. 21-41 ◽  
Author(s):  
M. E. Goldstein ◽  
S. J. Leib
Keyword(s):  
Boundary Layer ◽  
Small Amplitude ◽  
Three Dimensional ◽  
Cross Flow ◽  
Leading Edge ◽  
Streamwise Velocity ◽  
Linear Perturbation ◽  
Streamwise Vorticity ◽  
Dimensional Boundary ◽  
Layer Flow

We consider the effects of a small-amplitude, steady, streamwise vorticity field on the flow over an infinitely thin flat plate in an otherwise uniform stream. We show how the initially linear perturbation, ultimately leads to a small-amplitude but nonlinear cross-flow far downstream from the leading edge. This motion is imposed on the boundary-layer flow and eventually causes the boundary layer to separate. The streamwise velocity profiles within the boundary layer become inflexional in localized spanwise regions just upstream of the separation point. The flow in these regions is therefore susceptible to rapidly growing inviscid instabilities.

Experimental and Theoretical Investigation of the Supersonic Boundary Layer Stability on the Swept Wing

2008 ◽  
Vol 3 (3) ◽  
pp. 34-38
Author(s):  
Sergey A. Gaponov ◽  
Yuri G. Yermolaev ◽  
Aleksandr D. Kosinov ◽  
Nikolay V. Semionov ◽  
Boris V. Smorodsky
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Supersonic Boundary Layer ◽  
Mean Flow ◽  
Swept Wing ◽  
Wing Model ◽  
Dimensional Boundary ◽  
The Stability ◽  
Good Agreement

Theoretical and an experimental research results of the disturbances development in a swept wing boundary layer are presented at Mach number М = 2. In experiments development of natural and small amplitude controllable disturbances downstream was studied. Experiments were carried out on a swept wing model with a lenticular profile at a zero attack angle. The swept angle of a leading edge was 40°. Wave parameters of moving disturbances were determined. In frames of the linear theory and an approach of the local self-similar mean flow the stability of a compressible three-dimensional boundary layer is studied. Good agreement of the theory with experimental results for transversal scales of unstable vertices of the secondary flow was obtained. However the calculated amplification rates differ from measured values considerably. This disagreement is explained by the nonlinear processes observed in experiment

Prediction of Steady Propeller Performance with a Nonlinear Slipstream and Boundary-Layer Effect

1995 ◽  
Vol 39 (04) ◽  
pp. 297-312
Author(s):  
You-Hua Liu
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Viscous Drag ◽  
Viscous Effects ◽  
Lattice Method ◽  
Suction Force ◽  
Layer Effect ◽  
Dimensional Boundary ◽  
Propeller Performance

Both slipstream deformation and viscous effects are factors that affect the performance of a rotating marine propeller but neither of them has been properly treated in most of the current lifting-surface methods and surface panel theories. With the introduction of a partial roll-up wake model that is flexible to various cases of propeller geometry and loading condition, this paper presents a vortex-lattice method that can improve propeller performance prediction especially at heavy loading conditions. Some observations on the calculation of the blade leading-edge suction force and how to deduct it to account for the viscous drag increasing are given. The scale effect of propeller performance can be readily predicted by the quasi-three-dimensional boundary-layer calculation presented in this paper. Some patterns of the limiting streamlines on blade surfaces are also illustrated and compared with experimental results.

Boundary layer at a swept stagnation line of semi-infinite extent

1970 ◽  
Vol 41 (4) ◽  
pp. 737-750 ◽  
Author(s):  
Paul A. Libby ◽  
Karl K. Chen
Keyword(s):  
Boundary Layer ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Cross Flow ◽  
Differential Analysis ◽  
Eigenvalues And Eigenfunctions ◽  
Stagnation Line ◽  
Infinite Extent ◽  
Dimensional Boundary ◽  
Upstream Flow

A three-dimensional boundary layer developing along a semi-infinite swept stagnation line from a starting edge and evolving into that associated with such a line of infinite extent is calculated. A series solution useful for assessing the counteracting effects of cross-flow and mass transfer near the starting edge and for providing initial data for a subsequent streamwise, numerical solution is developed. The asymptotic behaviour far from the starting edge is examined and shown to involve only eigenfunction contributions associated with the far upstream flow. However, it is not presently possible to determine the relevant eigenvalues and eigenfunctions. Numerical solutions based on a difference-differential analysis yield the entire development of the boundary layer and indicate the streamwise length required for the case of the boundary layer at an infinite stagnation line to be obtained.

scholarly journals Receptivity mechanism of cross-flow instablity modes induced in three-dimensional boundary layer

2017 ◽  
Vol 66 (20) ◽  
pp. 204702
Author(s):  
Lu Chang-Gen ◽  
Zhu Xiao-Qing ◽  
Shen Lu-Yu
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Cross Flow ◽  
Dimensional Boundary

Control of Cross-Flow in a Three-Dimensional Boundary Layer Using a Multidischarge Actuator System

2021 ◽  
Vol 56 (1) ◽  
pp. 66-78
Author(s):  
S. A. Baranov ◽  
A. F. Kiselev ◽  
A. P. Kuryachii ◽  
D. S. Sboev ◽  
S. N. Tolkachev ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Cross Flow ◽  
Dimensional Boundary ◽  
Actuator System

Modelling the calmed region behind a spot

2005 ◽  
Vol 363 (1830) ◽  
pp. 1069-1078 ◽  
Author(s):  
S.N Brown ◽  
F.T Smith
Keyword(s):  
Boundary Layer ◽  
Theoretical Model ◽  
Slip Velocity ◽  
Three Dimensional ◽  
Cross Flow ◽  
Two Dimensional ◽  
Turbulent Spot ◽  
Mean Flow ◽  
Flow Surface ◽  
Dimensional Boundary

A theoretical model of the laminar ‘calmed region’ following a three-dimensional turbulent spot within a transitioning two-dimensional boundary layer is formulated and discussed. The flow is taken to be inviscid, and the perturbation mean flow surface streamlines calculated represent disturbances to the basic slip velocity. Available experimental evidence shows a fuller, more stable, streamwise profile in a considerable region trailing the spot, with cross-flow ‘inwash’ towards the line of symmetry. Present results are in qualitative agreement with this evidence.

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