Some Measurements of Boundary-Layer Growth in a Two-Dimensional Diffuser

1959 ◽  
Vol 81 (3) ◽  
pp. 285-294 ◽  
Author(s):  
J. F. Norbury
Keyword(s):  
Boundary Layer ◽  
Static Pressure ◽  
Momentum Equation ◽  
Layer Growth ◽  
Area Ratio ◽  
Momentum Thickness ◽  
Two Dimensional ◽  
Static Pressure Distribution ◽  
Boundary Layer Growth ◽  
Flow Experiments

Low-speed experiments were carried out in a two-dimensional diffuser having a square throat and an area ratio of two to one. Measurements were made of static pressure distribution, velocity contours at throat and outlet, and boundary-layer growth along the four wall center lines. Visual flow experiments were performed using tufts and smoke filaments. Similar experiments were carried out with the throat boundary layers artificially thickened by means of round rods placed on the walls upstream. Disparities between the measured growth of momentum thickness and that predicted by the simple momentum equation are discussed, as well as the effect of the artificial thickening on diffuser efficiency.

Effects of Curvature on Laminar Boundary Layers in Sink-Type Flows

1969 ◽  
Vol 91 (3) ◽  
pp. 353-358 ◽  
Author(s):  
W. A. Gustafson ◽  
I. Pelech
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Momentum Equation ◽  
Similarity Solutions ◽  
Momentum Thickness ◽  
Two Dimensional ◽  
Thickness Increase ◽  
Laminar Boundary Layers ◽  
Converging Channel ◽  
Special Case

The two-dimensional, incompressible laminar boundary layer on a strongly curved wall in a converging channel is investigated for the special case of potential velocity inversely proportional to the distance along the wall. Similarity solutions of the momentum equation are obtained by two different methods and the differences between the methods are discussed. The numerical results show that displacement and momentum thickness increase linearly with curvature while skin friction decreases linearly.

Calculation of Diffuser Efficiency for Two-Dimensional Flow

1947 ◽  
Vol 14 (3) ◽  
pp. A213-A216
Author(s):  
R. C. Binder
Keyword(s):  
Boundary Layer ◽  
Incompressible Flow ◽  
Potential Flow ◽  
Layer Growth ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Check Calculation ◽  
Two Dimensional Flow ◽  
Boundary Layer Growth ◽  
Potential Velocity

Abstract A method is presented for calculating the efficiency of a diffuser for two-dimensional, steady, incompressible flow without separation. The method involves a combination of organized boundary-layer data and frictionless potential-flow relations. The potential velocity and pressure are found after the boundary-layer growth is determined by a trial-and-check calculation.

Boundary-Layer Explorations Over a Two-Dimensional Mast/Sail Geometry

1990 ◽  
Vol 27 (04) ◽  
pp. 250-256
Author(s):  
Stuart Wilkinson
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Distribution ◽  
Skin Friction ◽  
Static Pressure ◽  
Separated Flow ◽  
Velocity Profiles ◽  
Two Dimensional ◽  
Representative Data ◽  
Static Pressure Distribution

An experimental aerodynamic boundary-layer investigation is performed over the suction surfaces of a typical two-dimensional mast/sail geometry. Velocity profiles are obtained at a number of locations which, together with visualization data and the corresponding static pressure distribution, are used to describe the fundamental nature of the complex partially separated flow field associated with such geometries. The velocity profiles are fully analyzed to provide thickness parameters and skin friction coefficients, suitable for use as representative data in the development of predictive theories involving viscid-inviscid interactions. The chordwise variations of the thickness parameters are graphically presented and discussed.

The boundary layer induced by a convected two-dimensional vortex

1984 ◽  
Vol 139 ◽  
pp. 1-28 ◽  
Author(s):  
T. L. Doligalski ◽  
J. D. A. Walker
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Layer Growth ◽  
Two Dimensional ◽  
Wall Boundary Layer ◽  
Constant Height ◽  
Boundary Layer Development ◽  
Layer Flow ◽  
The Right ◽  
Boundary Layer Growth

The response of a wall boundary layer to the motion of a convected vortex is investigated. The principal cases considered are for a rectilinear filament of strength –κ located a distance a above a plane wall and convected to the right in a uniform flow of speed U∞*. The inviscid solution predicts that such a vortex will remain at constant height a above the wall and be convected with constant speed αU∞*. Here α is termed the fractional convection rate of the vortex, and cases in the parameter range 0 [les ] α < 1 are considered. The motion is initiated at time t* = 0 and numerical calculations of the developing boundary-layer flow are carried out for α = 0, 0.2, 0.4, 0.55, 0.7, 0.75 and 0.8. For α < 0.75, a rapid lift-up of the boundary-layer streamlines and strong boundary-layer growth occurs in the region behind the vortex; in addition an unusual separation phenomenon is observed for α [les ] 0.55. For α [ges ] 0.75, the boundary-layer development is more gradual, but ultimately substantial localized boundary-layer growth also occurs. In all cases, it is argued that a strong inviscid–viscous interaction will take place in the form of an eruption of the boundary-layer flow. The generalization of these results to two-dimensional vortices with cores of finite dimension is discussed.

scholarly journals A Boundary Layer Transition Correlation for Concave Surfaces

1990 ◽  
Author(s):  
Farouk Hachem ◽  
Mark W. Johnson
Keyword(s):  
Boundary Layer ◽  
Growth Rate ◽  
Reynolds Numbers ◽  
Layer Growth ◽  
Boundary Layer Transition ◽  
Momentum Thickness ◽  
Free Stream Turbulence ◽  
Layer Growth Rate ◽  
Boundary Layer Growth ◽  
Boundary Layer Profile

The boundary layer profile is observed to be highly distorted by the momentum transfer associated with Taylor-Gortler vortices. This distortion has the effect or increasing the boundary layer growth rate and modifying the start-or-transition momentum thickness Reynolds numbers from the flat plate value. For modest curvatures, the vortices carry turbulence towards the blade which promotes transition, but as the curvature is increased further, the boundary layer profile shape is stabilised and transition is delayed. A model for the distorted boundary layer is presented and is used to predict the boundary layer growth rate and correlate the start or transition results in terms of the momentum thickness and blade radius Reynolds numbers and the free stream turbulence level. The degree or profile distortion needs to be accounted for when predicting the end or transition.

The Measurement of Boundary Layers on a Compressor Blade in Cascade: Part 1—A Unique Experimental Facility

1987 ◽  
Vol 109 (4) ◽  
pp. 520-526 ◽  
Author(s):  
S. Deutsch ◽  
W. C. Zierke
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Compressor Blade ◽  
Boundary Layer Transition ◽  
Two Dimensional ◽  
Suction Surface ◽  
Pressure Surface ◽  
Static Pressure Distribution

A unique cascade facility is described which permits the use of laser-Doppler velocimetry (LDV) to measure blade boundary layer profiles. Because of the need for a laser access window, the facility cannot reply on continuous blade pack suction to achieve two-dimensional, periodic flow. Instead, a strong suction upstream of the blade pack is used in combination with tailboards to control the flow field. The distribution of the upstream suction is controlled through a complex baffling system. A periodic, two–dimensional flow field is achieved at a chord Reynolds number of 500,000 and an incidence angle of 5 deg on a highly loaded, double circular arc, compressor blade. Inlet and outlet flow profiles, taken using five-hole probes, and the blade static-pressure distribution are used to document the flow field for use with the LDV measurements (see Parts 2 and 3). Inlet turbulence intensity is measured, using a hot wire, to be 0.18 percent. The static-pressure distribution suggests both separated flow near the trailing edge of the suction surface and an initially laminar boundary layer profile near the leading edge of the pressure surface. Probe measurements are supplemented by sublimation surface visualization studies. The sublimation studies place boundary layer transition at 64.2 ± 3.9 percent chord on the pressure surface, and indicate separation on the suction surface at 65.6 percent ± 3.5 percent chord.

Boundary-layer growth

1955 ◽  
Vol 231 (1184) ◽  
pp. 104-116 ◽  
Keyword(s):  
Boundary Layer ◽  
Stagnation Point ◽  
Momentum Equation ◽  
Separation Distance ◽  
Layer Growth ◽  
Infinite Plane ◽  
Initial Profile ◽  
First Approximation ◽  
Boundary Layer Growth ◽  
Rear Stagnation Point

The work presented here is an extension of that of Blasius (1908) on boundary-layer growth at a cylinder started from rest. It is shown that if an infinite plane moves in its own plane in a viscous fluid, the velocity distributions are similar at different times if the velocity V{t) of the plane is of the form V(t) = Atα or V(t) = A ect, where t is the time. These cases are then applied to the theory of boundary-layer growth and the second approximation to the velocity in the boundary layer is calculated. From this we find a first approximation for the distance travelled by the cylinder before separation starts. The second approximation to the separation distance was calculated by Blasius for α = 1, by Goldstein & Rosenhead (1936) for α = 0, and is found here for the case V(t) — A ect. Another approximate method for finding the separation distance, when separation starts at the rear stagnation point, is developed and applied to the impulsive start. The method is based on the momentum equation and assumes that the velocity profile near the rear stagnation point will always be similar to an initial profile. The numerical results are presented in the tables, and include the variation with a of the separation distance (according to the first approximation). It is hoped to use the method of Gortler (1944) to evaluate the drag on a circular cylinder and thus to discuss the initial motion of such a cylinder.

Two-Dimensional Flow Through a Diffuser With an Exit Length

1953 ◽  
Vol 20 (3) ◽  
pp. 390-392
Author(s):  
K. R. Galle ◽  
R. C. Binder
Keyword(s):  
Cross Section ◽  
Static Pressure ◽  
Pressure Rise ◽  
Layer Growth ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Uniform Cross Section ◽  
Flow Through ◽  
Boundary Layer Growth

Abstract A diffuser with an “exit length” is one with a channel of uniform cross section following the diffuser. Tests were made of different diffusers with and without exit lengths. The data were for steady, incompressible, two-dimensional flow. The performance of each diffuser was improved by the presence of an exit length. As compared to flow without an exit length, flow with an exit length is characterized by a reduced boundary-layer growth, by a small decrease in the pressure rise across the diverging section, and by a decrease in the static-pressure gradient at the diffuser inlet.

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