Theoretical Critical Height for Boundary Layer Transition on Airfoil Leading Edges

2017 ◽  
Author(s):  
Robert Robison ◽  
Eric Loth
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Transition ◽  
Critical Height ◽  
Layer Transition ◽  
Leading Edges

The Critical Height of Distributed Roughness to Cause Boundary Layer Transition

1959 ◽  
Vol 63 (588) ◽  
pp. 722-722
Author(s):  
R. L. Dommett
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Laminar Boundary Layer ◽  
Boundary Layer Transition ◽  
Critical Height ◽  
Layer Transition ◽  
Local Conditions ◽  
Additional Advantage ◽  
Boundary Layer Equations ◽  
General Method

It has been found that there is a critical height for “sandpaper” type roughness below which no measurable disturbances are introduced into a laminar boundary layer and above which transition is initiated at the roughness. Braslow and Knox have proposed a method of predicting this height, for flow over a flat plate or a cone, using exact solutions of the laminar boundary layer equations combined with a correlation of experimental results in terms of a Reynolds number based on roughness height, k, and local conditions at the top of the elements. A simpler, yet more general, method can be constructed by taking additional advantage of the linearity of the velocity profile near the wall in a laminar boundary layer.

scholarly journals Selection and impact of leading edge on boundary layer transition

2020 ◽  
Author(s):  
Dinesh Devraj Bhatia ◽  
Guangjun Yang ◽  
Guangning Li ◽  
Jian Wang
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Flow Structure ◽  
Leading Edge ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Stagnation Region ◽  
Leading Edges ◽  
The Impact ◽  
Selection Of

Abstract The choice of leading edge aspect ratio (AR) plays a crucial role when planning boundary layer experimental wind tunnel tests on a flat plate. Poor selection of the leading-edge profile hampers the effectiveness of the experiment and increases testing costs associated with interchanging of leading edges to attain accurate results. Thus, the appropriate selection of the leading edge is a very crucial part of the wind tunnel experimental process. The authors, in this paper, argue that the curvature of the leading edge and thus the AR are of paramount importance to attain accurate results from wind tunnel testing. In this paper, the authors have tested 7 different elliptical leading edges and compared their performance with an ideal leading edge with zero thickness. Experimental and computational has been presented for leading edges ranging from AR6 to AR20. Results were evaluated for boundary layer transition onset location and it was found that AR20 has the least influence on the flow structure when compared the ideal leading edge. A study of the flow structure at the stagnation point indicates an increase in adverse pressure gradient with an increase in the AR but also a decrease in the size of the stagnation region. The presence of a higher AR leading edge reduces the turbulent spot production rate which is one of the primary causes of boundary layer transition. The authors have presented a correlation which makes it easier for aerodynamicists to quantify the impact of the leading-edge AR on transition. A case is also presented to compare the relative performance of a wedge and the higher AR leading edge which gives potential researchers the choice between an elliptical or a wedge-shaped leading edge.

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF BOUNDARY LAYER TRANSITION ON BLUNTED CONES AT SUPERSONIC FLOW

2010 ◽  
Vol 40 (3) ◽  
pp. 309-319 ◽  
Author(s):  
V. N. Brazhko ◽  
A. V. Vaganov ◽  
N. A. Kovaleva ◽  
N. P. Kolina ◽  
I. I. Lipatov
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Numerical Investigations

Automatic control of laminar boundary-layer transition

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 85-90
Author(s):  
P. A. Nelson ◽  
M. C. M. Wright ◽  
J.-L. Rioual
Keyword(s):  
Boundary Layer ◽  
Automatic Control ◽  
Laminar Boundary Layer ◽  
Boundary Layer Transition ◽  
Layer Transition
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