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

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

1953 ◽  
Author(s):  
NORTHROP AIRCRAFT INC HAWTHORNE CA
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
High Lift ◽  
Boundary Layer Suction

Boundary layer suction for high-speed air intakes: A review

2018 ◽  
Vol 233 (9) ◽  
pp. 3459-3481 ◽  
Author(s):  
Javad Sepahi-Younsi ◽  
Behzad Forouzi Feshalami ◽  
Seyed Reza Maadi ◽  
Mohammad Reza Soltani
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Flow Control ◽  
High Speed ◽  
Control Methods ◽  
Slant Angle ◽  
Boundary Layer Suction ◽  
Recent Developments

The paper summarizes recent developments in boundary layer suction for high-speed air intakes. Bleed has been efficiently used in supersonic and hypersonic intakes for three primary reasons: to improve the performance of the intake, to reduce the starting Mach number of the intake, and to postpone the onset of buzz oscillations. A bleed system has many characteristics such as the bleed entrance and exit areas, bleed entrance slant angle and position, and bleed type (slot or porous and ram-scoop or flush). Each of these parameters has significant impacts on the intake performance and stability that have been reviewed in this study. In addition, the effectiveness of other flow control methods has been compared with the bleed method.

Some Developments in Boundary Layer Research in the Past Thirty Years

1960 ◽  
Vol 64 (590) ◽  
pp. 64-80 ◽  
Author(s):  
H. Schlichting
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
High Speed ◽  
Boundary Layer Theory ◽  
Boundary Layer Control ◽  
High Lift ◽  
The Past ◽  
High Mach ◽  
Swept Wings ◽  
Layer Control

SummaryBoundary layer theory is the cornerstone of our knowledge of the flow of air and other fluids of small viscosity under circumstances of interest in many engineering applications, especially also in aeronautics. Many complex problems in aerodynamics, as for instance the problem of skin friction, which was theoretically attacked very early by F. W. Lanchester, have been clarified by studying the flow within the boundary layer and its effects on the general flow around the body.Research work on boundary layers, as started by Prandtl in 1904. was for the first twenty years—up to Prandtl's Wilbur Wright Memorial Lecture to the Royal Aeronautical Society in 1927—almost entirely restricted to Prandtl's Institute at Göttingen. But since about 1930 boundary layer theory has been generally accepted, and in the past thirty years there has been an almost exponential rise of the number of contributors to its further development.The author tries to trace certain lines, along which this important branch of modern fluid dynamics has developed in the past thirty years. In this connection the following topics are treated to some extent:I.Transition from laminar to turbulent flow.II.Boundary layer control for high lift and low drag of aerofoils.III.Aerodynamic heating at high speed (high Mach numbers).IV.Boundary layer efff cts on swept wings and on rotating bodies.I. The theoretical investigations of the problem of transition start from Reynolds' and Lord Rayleigh's hypothesis of the instability of laminar flow. After many unsuccessful attempts Tollmien, 1930, finally succeeded in calculating the critical Reynolds number for the boundary layer on a flat plate. More than ten years later Tollmien's stability theory was completely confirmed by very careful experiments of Dryden and his co-workers.II. After many wind tunnel experiments the investigations of boundary layer control for high lift of aerofoils led to the construction of two aeroplanes with boundary layer suction at the aerodynamische versuchsanstalt gottingen, in 1938, which were quite successful. later on, also, a considerable reduction of the skin friction of aerofoils was obtained with the advent of the laminar flow aerofoil.III. In flow at high Mach numbers the velocity boundary layer is accompanied by a thermal boundary layer which is caused by frictional heating. The large increase in the temperature of a solid surface in a high speed stream which can be calculated from boundary layer theory only, poses a serious problem to aeronautical engineers (“thermal barrier”).IV. The aerodynamic characteristics of swept wings and Delta wings are largely governed by the behaviour of their boundary layer. Some of the draw-backs of such wing plan forms can be remedied by boundary layer control, as for instance by a “boundary layer fence.” For turbo-machines the influence of the centrifugal forces on the boundary layer plays an important role for their aerodynamic coefficients.

On the Performance of Boundary Layer Suction for Secondary Flow Control in a High Speed Compressor Cascade

2013 ◽  
Author(s):  
Karsten Liesner ◽  
Robert Meyer ◽  
Christoph Gmelin ◽  
Frank Thiele
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Secondary Flow ◽  
High Speed ◽  
Compressor Cascade ◽  
Boundary Layer Suction

Wake Control by Boundary Layer Suction Applied to a High-Lift Low-Pressure Turbine Blade

2010 ◽  
Author(s):  
Francesca Satta ◽  
Marina Ubaldi ◽  
Pietro Zunino ◽  
Claudia Schipani
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Suction Side ◽  
Low Pressure ◽  
High Lift ◽  
Velocity Defect ◽  
Boundary Layer Suction ◽  
Low Pressure Turbine ◽  
Rear Part

Wake control by boundary layer suction has been applied to a high-lift low-pressure turbine blade with the intention of reducing the wake velocity defect, hence attenuating wake-blade interaction, and consequently the generation of tonal noise. The experimental investigation has been performed in a large scale linear turbine cascade at midspan. Two Reynolds number conditions (Re = 300000 and Re = 100000), representative of the typical operating conditions of the low pressure aeroengine turbines, have been analyzed. Boundary layer suction has been implemented through a slot placed in the rear part of the profile suction side. The suction rate has been varied in order to investigate its influence on the wake reduction. Mean velocity and Reynolds stress components in the blade to blade plane have been measured by means of a two-component crossed miniature hot-wire. The wake shed from the central blade has been investigated in several traverses in the direction normal to the camber line at the cascade exit. The traverses are located at distances ranging between 5 and 80% of the blade chord from the blade trailing edge. To get an overall estimate of the wake velocity defect reductions obtained by the application of boundary layer suction, the integral parameters of the wake have been also estimated. Moreover, spectra of the velocity fluctuations have been evaluated to get information on the unsteady behaviour of the wake flow when boundary layer suction is applied. The results obtained in the wake controlled by boundary layer suction have been compared with the results in the baseline profile wake at both Reynolds number conditions for the purpose of evaluating the control technique effectiveness. The removal of boundary layer through the slot in the rear part of the profile suction side has been proved to be very effective in reducing the wake shed from the profile. The results show that a reduction greater than 65% of the wake displacement and momentum thicknesses at Re = 300000, and a reduction greater than 75% at Re = 100000 can be achieved by removal of 1.5% and 1.8% of the single passage through flow, respectively.

Griffith Diffusers

1979 ◽  
Vol 101 (4) ◽  
pp. 473-477 ◽  
Author(s):  
Tah-teh Yang ◽  
C. D. Nelson
Keyword(s):  
Boundary Layer ◽  
Inverse Method ◽  
Area Ratio ◽  
Two Dimensional ◽  
High Lift ◽  
Boundary Layer Suction ◽  
Through Flow ◽  
Typical Performance ◽  
Method Of Solution ◽  
Layer Control

Contoured wall diffusers are designed by using an inverse method. The prescribed wall velocity distribution(s) was taken from the high lift airfoil designed by A. A. Griffith in 1938; therefore, such diffusers are named Griffith diffusers. First the formulation of the inverse problem and the method of solution are outlined. Then the typical contour of a two-dimensional diffuser and velocity distributions across the flow channel at various stations are presented. For a Griffith diffuser to operate as it is designed, boundary layer suction is necessary. Discussion of the percentage of through-flow required to be removed for the purpose of boundary layer control is given. The typical performance is presented for a Griffith diffuser having the ratio (Cpmeasured / Cpideal) = 98 percent and at the exit plane the ratio of (Ulocal − Uavg.) / Uavg. = ± 5 percent. Finally, reference is made to the latest version of a computer program for a two-dimensional diffuser requiring only area ratio, nondimensional length and suction percentage as inputs.

Combination of Active and Passive Flow Control in a High Speed Compressor Cascade

2014 ◽  
Author(s):  
Karsten Liesner ◽  
Robert Meyer
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
High Speed ◽  
Active Flow Control ◽  
Side Wall ◽  
Suction Side ◽  
Experimental Investigations ◽  
Two Dimensional ◽  
Compressor Cascade ◽  
Boundary Layer Suction

An experimental study is presented in which passive and active flow control are combined in a way that they complement and support one other. Secondary flow control using boundary layer fences is combined with a boundary layer suction in a compressor cascade at high Mach numbers. Inflow Mach number of 0.67 and Reynolds number (based on chord length) of 560.000 assure realistic conditions. The cascade, equipped with five stator vanes of NACA65 K48 type is used in an ambient condition measurement environment. Pressure measurements form the basis of the experimental investigations, flow visualization is used to obtain insight into the topology of the flow field. The boundary layer fences installed on the suction side of the vanes create a region of low-loss two dimensional flow in the center of the passage. A region of high flow loss is generated at the side wall between wall and BL fence. This region is treated with through-wall boundary layer suction as used in previous investigations. This helps stabilize the flow near the wall and prevent large separated areas. The total pressure loss is reduced remarkably and the outflow becomes more two-dimensional compared to the reference measurement and even compared to the measurement with suction applied without BL fences. The application of boundary layer fences on flow-suction experiments allows obtaining the same loss reduction gains by using lower amounts of suction.

Effect of Segment Endwall Boundary Layer Suction on Compressor 3D Corner Separation

2015 ◽  
Author(s):  
Ping-Ping Chen ◽  
Wei-Yang Qiao ◽  
Karsten Liesner ◽  
Robert Meyer
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Base Flow ◽  
Flow Ratio ◽  
Compressor Cascade ◽  
Corner Separation ◽  
Boundary Layer Suction ◽  
Suction Flow

Due to the strong secondary flow behavior in the compressor endwall/blade suction-side corner region, a large three-dimensional corner separation will usually be formed with large amounts of compressor aerodynamic loss. In this paper, a linear high-speed compressor cascade, with five NACA 65-K48 stator profiles, is numerically simulated to understand the state of this phenomenon. Based on the experiment, the base flow is validated for the numerical result. Active control of 3D corner separation was investigated by using segment endwall boundary layer suction, which is located along the pressure-side leg of leading-edge horse-shoe vortex during its development in the frontal part of the blade passage. The influence of suction flow ratio was investigated in an effort to quantify the improvements of compressor cascade performance. The results show the optimal suction flow ratio is not the largest, but a critical value, which is 0.83% of inflow mass flow rate. Taking all performance parameters’ changes into consideration, the best is with 1% suction flow ratio. The total-pressure loss is eventually reduced by 11.2% with the optimal suction flow ratio compared to the design condition, and an increase of 9.84% is obtained for the static-pressure ratio.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

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