Measurements of the Boundary Layer Development along a Turbine Blade with Rough Surfaces

1980 ◽  
Vol 102 (4) ◽  
pp. 978-983 ◽  
Author(s):  
K. Bammert ◽  
H. Sandstede
Keyword(s):  
Boundary Layer ◽  
Rough Surfaces ◽  
Chord Length ◽  
Smooth Surfaces ◽  
Turbine Cascade ◽  
Boundary Layer Development ◽  
Turbine Cascades ◽  
Layer Development ◽  
Good Agreement

During the operation of turbines the surfaces of the blades are roughened by corrosion, erosion and deposits. The generated roughness is usually greater than that produced by manufacture. The quality of the blade surfaces determines the losses of energy conversion in turbine cascades to a great extent. The loss coefficient can be found theoretically by a boundary layer calculation. For rough surfaces there are no boundary layer measurements along the profiles of a turbine cascade. Therefore in a cascade wind tunnel measurements of the boundary layer development were carried out. The chord length of the blades was 175 mm. The cascade represented a section through the stator blades of a 50 percent reaction gas turbine. For smooth surfaces and three different roughnesses up to 3.3 · 10−3 (equivalent sand roughness related to chord length) the boundary layers were measured. The momentum thickness is up to three times as great as that on smooth surfaces. Especially in regions with decelerated flow the effects of roughness are high. A rough surface causes a rise of the friction factor and a shift of the transition of laminar to turbulent flow. The results of the measurements are shown. Correction factors are worked out to get good agreement between measurement and calculation according to the Truckenbrodt theory.

scholarly journals Influence of Endwall Flow on Airfoil Suction Surface Mid-Height Boundary Layer Development in a Turbine Cascade

1982 ◽  
Author(s):  
O. P. Sharma ◽  
R. A. Graziani
Keyword(s):  
Boundary Layer ◽  
Reynolds Shear Stress ◽  
Cross Flow ◽  
Prediction Method ◽  
Conservation Equation ◽  
Turbine Cascade ◽  
Suction Surface ◽  
Extra Term ◽  
Boundary Layer Development ◽  
Layer Development

This paper presents the results of an analysis to assess the influence of cascade passage endwall flow on the airfoil suction surface mid-height boundary layer development in a turbine cascade. The effect of the endwall flow is interpreted as the generation of a cross flow and a cross flow velocity gradient in the airfoil boundary layer, which results in an extra term in the mass conservation equation. This extra term is shown to influence the boundary layer development along the mid-height of the airfoil suction surface through an increase in the boundary layer thickness and consequently an increase in the mid-height losses, and a decrease in the Reynolds shear stress, mixing length, skin friction, and Stanton number. An existing two-dimensional differential boundary layer prediction method, STAN-5, is modified to incorporate the above two effects.

Boundary-layer development at a two-dimensional rear stagnation point

1972 ◽  
Vol 56 (1) ◽  
pp. 161-171 ◽  
Author(s):  
A. J. Robins ◽  
J. A. Howarth
Keyword(s):  
Boundary Layer ◽  
Stagnation Point ◽  
Equations Of Motion ◽  
Two Dimensional ◽  
Initial Value ◽  
Boundary Layer Development ◽  
Leading Term ◽  
Layer Development ◽  
Rear Stagnation Point ◽  
Good Agreement

This paper examines the nature of the development of two-dimensional laminar flow of an incompressible fluid at the rear stagnation point on a cylinder which is started impulsively from rest. Proudman & Johnson (1962) first examined this type of flow, andobtainedasimilarity solution of the inviscid form of the equations of motion. This solution describes the nature of the flow at large distances from the surface, for large times after the start of the motion. Here, the flow at the rear stagnation point is examined in greater detail. The solution found by Proudman & Johnson constitutes the leading term in an asymptotic expansion, valid for large times. Further terms in this expansion are now calculated, and the method of matched asymptotic expansions is used to obtain an inner solution describing the flow near the surface. A numerical integration of the full initial-value problem gives good agreement with the analytical solution.

Approximate Analysis of Transient Laminar Boundary-Layer Development

1968 ◽  
Vol 90 (4) ◽  
pp. 452-456 ◽  
Author(s):  
J. A. Schetz ◽  
Sin K. Oh
Keyword(s):  
Boundary Layer ◽  
Velocity Field ◽  
Development Time ◽  
Constant Density ◽  
Boundary Layer Development ◽  
New Type ◽  
Momentum Integral ◽  
Layer Development ◽  
Surrounding Fluid ◽  
Good Agreement

Transient development of the boundary layer on a flat plate following the impulsive start of motion of the surrounding fluid is analyzed approximately. The Howarth-Dorodnitzin transformation and a Crocco Integral are used to relate the temperature field to the approximate velocity field which is obtained in a “constant density” plane. The solution for the velocity field is determined using the unsteady Momentum Integral equation with a new type of profile. Expressions for the boundary-layer development time and model surface temperature at the end of the development time are presented. Good agreement with a roughly determined experimental flow development time is achieved.

scholarly journals Detailed Velocity and Turbulence Measurements of the Profile Boundary Layer in a Large Scale Turbine Cascade

1996 ◽  
Author(s):  
Marina Ubaldi ◽  
Pietro Zunino ◽  
Ugo Campora ◽  
Andrea Ghiglione
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Field Investigation ◽  
Laser Doppler Velocimeter ◽  
Turbine Cascade ◽  
Mean Velocity ◽  
Boundary Layer Development ◽  
Stress Boundary ◽  
Hot Film ◽  
Layer Development

Extensive measurements of velocity and turbulence have been performed by means of a two-component fibre-optic laser Doppler velocimeter, to investigate the profile boundary layer development on a large scale turbine cascade. Flow field investigation has been integrated with data obtained by surface-mounted hot-film gauges in order to get direct information on the boundary layer nature and on its time varying characteristics. Measurements were detailed enough to allow constructing mean velocity and Reynolds stress boundary layer profiles giving an in-depth description of the boundary layer development along both suction and pressure surfaces through laminar, transitional and turbulent regimes.

Influence of Endwall Flow on Airfoil Suction Surface Midheight Boundary Layer Development in a Turbine Cascade

1983 ◽  
Vol 105 (1) ◽  
pp. 147-155 ◽  
Author(s):  
O. P. Sharma ◽  
R. A. Graziani
Keyword(s):  
Boundary Layer ◽  
Reynolds Shear Stress ◽  
Prediction Method ◽  
Mass Conservation ◽  
Conservation Equation ◽  
Turbine Cascade ◽  
Suction Surface ◽  
Extra Term ◽  
Boundary Layer Development ◽  
Layer Development

This paper presents the results of an analysis to assess the influence of cascade passage endwall flow on the airfoil suction surface midheight boundary layer development in a turbine cascade. The effect of the endwall flow is interpreted as the generation of a crossflow and a crossflow velocity gradient in the airfoil boundary layer which results in an extra term in the mass conservation equation. This extra term is shown to infuence the boundary layer development along the midheight of the airfoil suction surface through an increase in the boundary layer thickness and consequently an increase in the midheight losses, and a decrease in the Reynolds shear stress, mixing length, skin friction, and Stanton number. An existing two-dimensional differential boundary layer prediction method, STAN-5, is modified to incorporate the above two effects.

Assessing the Influence of Aerosol on Radiation and Its Roles in Planetary Boundary Layer Development

2021 ◽  
Vol 35 (2) ◽  
pp. 384-392
Author(s):  
Zhigang Cheng ◽  
Yubing Pan ◽  
Ju Li ◽  
Xingcan Jia ◽  
Xinyu Zhang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Boundary Layer Development ◽  
Layer Development
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