Attachment-Line Transition and Boundary-Layer Relaminarization on a High-Lift Wing in Flight

1996 ◽  
Author(s):  
V. Eric Roback ◽  
C. P. van Dam ◽  
Stephanie M. Los ◽  
Long P. Yip ◽  
Daniel W. Banks
Keyword(s):  
Boundary Layer ◽  
High Lift ◽  
Attachment Line

Attachment-Line Transition and Boundary-Layer Relaminarization on a High-Lift Wing in Flight

1996 ◽  
Author(s):  
V.E. ROBACK ◽  
LONG YIP ◽  
DANIEL BANKS ◽  
C.P. DAM ◽  
STEPHANIE LOS
Keyword(s):  
Boundary Layer ◽  
High Lift ◽  
Attachment Line

Direct simulation of evolution and control of three-dimensional instabilities in attachment-line boundary layers

1995 ◽  
Vol 291 ◽  
pp. 369-392 ◽  
Author(s):  
Ronald D. Joslin
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Plate Boundary ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
Attachment Line

The spatial evolution of three-dimensional disturbances in an attachment-line boundary layer is computed by direct numerical simulation of the unsteady, incompressible Navier–Stokes equations. Disturbances are introduced into the boundary layer by harmonic sources that involve unsteady suction and blowing through the wall. Various harmonic-source generators are implemented on or near the attachment line, and the disturbance evolutions are compared. Previous two-dimensional simulation results and nonparallel theory are compared with the present results. The three-dimensional simulation results for disturbances with quasi-two-dimensional features indicate growth rates of only a few percent larger than pure two-dimensional results; however, the results are close enough to enable the use of the more computationally efficient, two-dimensional approach. However, true three-dimensional disturbances are more likely in practice and are more stable than two-dimensional disturbances. Disturbances generated off (but near) the attachment line spread both away from and toward the attachment line as they evolve. The evolution pattern is comparable to wave packets in flat-plate boundary-layer flows. Suction stabilizes the quasi-two-dimensional attachment-line instabilities, and blowing destabilizes these instabilities; these results qualitatively agree with the theory. Furthermore, suction stabilizes the disturbances that develop off the attachment line. Clearly, disturbances that are generated near the attachment line can supply energy to attachment-line instabilities, but suction can be used to stabilize these instabilities.

Unsteady fluidic oscillators for active controlling boundary layer separation in an ultra-high-lift low-pressure turbine

2021 ◽  
pp. 107130
Author(s):  
Xiao Qu ◽  
Yingjie Zhang ◽  
Xingen Lu ◽  
Junqiang Zhu ◽  
Yanfeng Zhang
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Separation ◽  
Low Pressure ◽  
High Lift ◽  
Layer Separation ◽  
Low Pressure Turbine

Boundary Layer Development in the BR710 and BR715 LP Turbines—The Implementation of High-Lift and Ultra-High-Lift Concepts

2002 ◽  
Vol 124 (3) ◽  
pp. 385-392 ◽  
Author(s):  
R. J. Howell ◽  
H. P. Hodson ◽  
V. Schulte ◽  
R. D. Stieger ◽  
Heinz-Peter Schiffer ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Test Facility ◽  
Surface Boundary ◽  
Unsteady Boundary Layer ◽  
Suction Surface ◽  
High Lift ◽  
Surface Boundary Layer ◽  
Cold Flow ◽  
Layer Behavior ◽  
Lp Turbine

This paper describes a detailed study into the unsteady boundary layer behavior in two high-lift and one ultra-high-lift Rolls-Royce Deutschland LP turbines. The objectives of the paper are to show that high-lift and ultra-high-lift concepts have been successfully incorporated into the design of these new LP turbine profiles. Measurements from surface mounted hot film sensors were made in full size, cold flow test rigs at the altitude test facility at Stuttgart University. The LP turbine blade profiles are thought to be state of the art in terms of their lift and design philosophy. The two high-lift profiles represent slightly different styles of velocity distribution. The first high-lift profile comes from a two-stage LP turbine (the BR710 cold-flow, high-lift demonstrator rig). The second high-lift profile tested is from a three-stage machine (the BR715 LPT rig). The ultra-high-lift profile measurements come from a redesign of the BR715 LP turbine: this is designated the BR715UHL LP turbine. This ultra-high-lift profile represents a 12 percent reduction in blade numbers compared to the original BR715 turbine. The results from NGV2 on all of the turbines show “classical” unsteady boundary layer behavior. The measurements from NGV3 (of both the BR715 and BR715UHL turbines) are more complicated, but can still be broken down into classical regions of wake-induced transition, natural transition and calming. The wakes from both upstream rotors and NGVs interact in a complicated manner, affecting the suction surface boundary layer of NGV3. This has important implications for the prediction of the flows on blade rows in multistage environments.

Investigation of the Boundary Layer Behavior In the Vicinity of the Attachment Line on a Yawed Wing and the Possibilities of Deturbulization

1998 ◽  
Vol 33 (5) ◽  
pp. 694-700
Author(s):  
V. M. Filippov ◽  
G. K. Shapovalov
Keyword(s):  
Boundary Layer ◽  
Layer Behavior ◽  
Attachment Line

Comparative study of boundary layer control around an ordinary airfoil and a high lift airfoil with secondary blowing

2018 ◽  
Vol 164 ◽  
pp. 50-63 ◽  
Author(s):  
Sandeep Eldho James ◽  
Abhilash Suryan ◽  
Jiss J Sebastian ◽  
Abhay Mohan ◽  
Heuy Dong Kim
Keyword(s):  
Boundary Layer ◽  
Comparative Study ◽  
Boundary Layer Control ◽  
High Lift ◽  
Layer Control

Investigation of Formation and Development of Stationary and Secondary Disturbances in the Favourable Pressure Gradient Area on the Swept Wing

2013 ◽  
Vol 8 (2) ◽  
pp. 55-69
Author(s):  
Stepan Tolkachev ◽  
Vasily Gorev ◽  
Viktor Kozlov
Keyword(s):  
Boundary Layer ◽  
Roughness Element ◽  
Swept Wing ◽  
Liquid Crystal Thermography ◽  
Natural Case ◽  
Turbulent Transition ◽  
Stage Transition ◽  
The Moment ◽  
Combined Technique ◽  
Attachment Line

In this work the combined technique of liquid-crystal thermography and thermoanemometry measurements is used to trace the stationary disturbance development from the moment of formation to the nonlinear stage transition. It has been shown that the pair of stationary vortices are formed after the cylindrical roughness element. These vortices modify a boundary layer and destabilize it. There is the area of maximal receptivity to the roughness location, which in the experiment was distant from the attachment line. If the stationary disturbance has enough magnitude in its core the secondary disturbances excite and lead to the laminar-turbulent transition. Secondary disturbances are sensitive to the acoustics and achieve the magnitude in hundred times higher than for the natural case

RESEARCH ON HIGH LIFT BOUNDARY LAYER SUCTION INVESTIGATIONS ON THIN HIGH SPEED WINGS

1952 ◽  
Author(s):  
NORTHROP AIRCRAFT INC HAWTHORNE CA
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
High Lift ◽  
Boundary Layer Suction
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