Structure of local pressure-driven three-dimensional transient boundary-layer separation

AIAA Journal ◽  
1994 ◽  
Vol 32 (5) ◽  
pp. 997-1005 ◽  
Author(s):  
Laura L. Pauley
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Boundary Layer Separation ◽  
Local Pressure ◽  
Layer Separation ◽  
Pressure Driven

Comparison of Experimental and Computational Shock Structure in a Transonic Compressor Rotor

1981 ◽  
Vol 103 (1) ◽  
pp. 78-88
Author(s):  
G. Haymann-Haber ◽  
W. T. Thompkins
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Boundary Layer Separation ◽  
Shock Strength ◽  
Layer Separation ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Pressure Peak ◽  
Rotor Losses

Measurement of passage shock strength in a transonic compressor rotor using a gas fluorescent technique revealed an unexpected variation in shock strength in the radial direction. An axisymmetric idealization would normally predict that the passage shock strength would gradually weaken when moving radially inward until disappearing at the sonic radius. However, the measurements indicated a sharp peak in strength at the nominal sonic radius. Blade boundary layer separation originating at this point accounts for about one half of the total rotor losses. A numerical computation of the three-dimensional inviscid flow, using time-marching techniques, has accurately predicted in general the radial and tangential variations in passage shock strength and in particular the sharp pressure peak at the nominal sonic radius. The overall shock strength was somewhat over-predicted, but this overprediction may be the result of boundary layer separation in the experiment. This paper presents comparisons between the optical density measurements and computational results and in addition a short analytical discussion which demonstrates that the sharp shock strength rise may occur in many transonic compressor rotors.

Autogenous Suction to Prevent Laminar Boundary-Layer Separation

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Hediye Atik ◽  
Leon van Dommelen
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Separation ◽  
Laminar Flows ◽  
Computational Techniques ◽  
Pressure Gradients ◽  
Practical Application ◽  
Theoretical Limit ◽  
Local Pressure ◽  
Layer Separation ◽  
Straightforward Application

Boundary-layer separation can be prevented or delayed by sucking part of the boundary layer into the surface, but in a straightforward application the required hydraulics entail significant penalties in terms of weight and cost. By means of computational techniques, this paper explores the possibility of autogenous suction, in which the local pressure differences that lead to separation drive the suction used to prevent it. The chosen examples include steady and unsteady laminar flows around leading edges of thin airfoils. No fundamental theoretical limit to autogenous suction was found in the range of angles of attack that could be studied, but rapidly increasing suction volumes suggest that practical application will become increasingly difficult for more severe adverse pressure gradients.

scholarly journals On the use of lagrangian variables in descriptions of unsteady boundary-layer separation

1990 ◽  
Vol 333 (1631) ◽  
pp. 343-378 ◽  
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Boundary Layer Separation ◽  
Lagrangian Description ◽  
Unsteady Boundary Layer ◽  
Layer Separation ◽  
Unsteady Separation ◽  
Lagrangian Variables ◽  
Classical Boundary ◽  
Layer Region

The lagrangian description of unsteady boundary-layer separation is reviewed from both analytical and numerical perspectives. We explain in simple terms how particle distortion gives rise to unsteady separation, and why a theory centred on lagrangian coordinates provides the clearest description of this phenomenon. Included in the review are some of the more recent results for unsteady three-dimensional compressible separation. The different forms of separation that can arise from symmetries are emphasized. Current work includes a possible description of separation when the detaching vorticity layer exits the classical boundary-layer region, but still remains much closer to the surface than a typical body length-scale.

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