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 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.

Heat Transfer Measurements Downstream of a Two-Dimensional Jet Entering a Crossflow

1987 ◽  
Vol 109 (4) ◽  
pp. 572-578 ◽  
Author(s):  
S. Wittig ◽  
V. Scherer
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Pressure Distribution ◽  
Momentum Flux ◽  
Static Pressure ◽  
Flux Ratio ◽  
Main Flow ◽  
Two Dimensional ◽  
Reattachment Point ◽  
Static Pressure Distribution

Nusselt and Stanton numbers have been evaluated in and behind the recirculating zone produced by a two-dimensional jet entering a crossflow. The momentum flux ratio of the jet to the main flow was varied from 1.44–8.4 and measurements of the static pressure distribution and of the flow field by a five-hole probe were performed. A relation between the location of the reattachment point of the flow and the maximum of heat transfer was observed. Comparisons with available data are made. The experiments are intended for the verification of calculational codes.

Large Eddy Simulation of Boundary Layer Transition Mechanisms in a Gas-Turbine Compressor Cascade

2018 ◽  
Author(s):  
Ashley D. Scillitoe ◽  
Paul G. Tucker ◽  
Paolo Adami
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Boundary Layer Transition ◽  
Bypass Transition ◽  
Suction Surface ◽  
Layer Transition ◽  
Turbulent Spots ◽  
Pressure Surface ◽  
Eddy Simulation ◽  
Large Eddy

Large Eddy Simulation (LES) is used to explore the boundary layer transition mechanisms in two rectilinear compressor cascades. To reduce numerical dissipation, a novel locally adaptive smoothing scheme is added to an unstructured finite-volume solver. The performance of a number of Sub-Grid Scale (SGS) models is explored. With the first cascade, numerical results at two different freestream turbulence intensities (Ti’s), 3.25% and 10%, are compared. At both Ti’s, time-averaged skin-friction and pressure coefficient distributions agree well with previous Direct Numerical Simulations (DNS). At Ti = 3.25%, separation induced transition occurs on the suction surface, whilst it is bypassed on the pressure surface. The pressure surface transition is dominated by modes originating from the convection of Tollmien-Schlichting waves by Klebanoff streaks. However, they do not resembled a classical bypass transition. Instead, they display characteristics of the “overlap” and “inner” transition modes observed in the previous DNS. At Ti = 10%, classical bypass transition occurs, with Klebanoff streaks incepting turbulent spots. With the second cascade, the influence of unsteady wakes on transition is examined. Wake-amplified Klebanoff streaks were found to instigate turbulent spots, which periodically shorten the suction surface separation bubble. The celerity line corresponding to 70% of the free-stream velocity, which is associated with the convection speed of the amplified Klebanoff streaks, was found to be important.

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.

Clocking Effects in a 1.5-Stage Axial Turbine: Boundary Layer Behaviour at Midspan

2004 ◽  
Author(s):  
Sven Ko¨nig ◽  
Axel Heidecke ◽  
Bernd Stoffel ◽  
Andreas Fiala ◽  
Karl Engel
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Discretization Scheme ◽  
Low Pressure Turbine ◽  
Finite Volume Discretization ◽  
Hot Film

This paper presents an experimental and numerical investigation on the influence of clocking on the boundary layer behaviour of the second stator in a 1.5-stage axial low pressure turbine. Surface mounted hot-film sensors were used to measure the quasi shear stress on the second stator and static pressure tappings to obtain the pressure distribution. All experiments were carried out at midspan for different clocking positions. The supporting numerical calculations were conducted with a two-dimensional Navier-Stokes solver using a finite volume discretization scheme and the v′2f turbulence model.

scholarly journals Measured and Calculated Wall Temperatures on Air-Cooled Turbine Vanes With Boundary Layer Transition

1983 ◽  
Author(s):  
Curt H. Liebert ◽  
Raymond E. Gaugler ◽  
Herbert J. Gladden
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
Separation Bubble ◽  
Boundary Layer Transition ◽  
Suction Surface ◽  
Layer Transition ◽  
Pressure Surface ◽  
Lower Reynolds Number ◽  
High Reynolds

Convection cooled turbine vane metal wall temperatures experimentally obtained in a hot cascade for a given one-vane design were compared with wall temperatures calculated with TACT1 and STAN5 computer codes which incorporated various models for predicting laminar-to-turbulent boundary layer transition. Favorable comparisons on both vane surfaces were obtained at high Reynolds number with only one of these transition models. When other models were used, temperature differences between calculated and experimental data obtained at the high Reynolds number were as much as 14 percent in the separation bubble region of the pressure surface. On the suction surface and at lower Reynolds number, predictions and data unsatisfactorily differed by as much as 22 percent. Temperature differences of this magnitude can represent orders of magnitude error in blade life prediction.

Large Eddy Simulation of Boundary Layer Transition Mechanisms in a Gas-Turbine Compressor Cascade

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Ashley D. Scillitoe ◽  
Paul G. Tucker ◽  
Paolo Adami
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Boundary Layer Transition ◽  
Bypass Transition ◽  
Suction Surface ◽  
Layer Transition ◽  
Turbulent Spots ◽  
Pressure Surface ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulation (LES) is used to explore the boundary layer transition mechanisms in two rectilinear compressor cascades. To reduce numerical dissipation, a novel locally adaptive smoothing (LAS) scheme is added to an unstructured finite volume solver. The performance of a number of subgrid scale (SGS) models is explored. With the first cascade, numerical results at two different freestream turbulence intensities (Ti's), 3.25% and 10%, are compared. At both Ti's, time-averaged skin-friction and pressure coefficient distributions agree well with previous direct numerical simulations (DNS). At Ti = 3.25%, separation-induced transition occurs on the suction surface, while it is bypassed on the pressure surface. The pressure surface transition is dominated by modes originating from the convection of Tollmien–Schlichting waves by Klebanoff streaks. However, they do not resemble a classical bypass transition. Instead, they display characteristics of the “overlap” and “inner” transition modes observed in the previous DNS. At Ti = 10%, classical bypass transition occurs, with Klebanoff streaks incepting turbulent spots. With the second cascade, the influence of unsteady wakes on transition is examined. Wake-amplified Klebanoff streaks were found to instigate turbulent spots, which periodically shorten the suction surface separation bubble. The celerity line corresponding to 70% of the free-stream velocity, which is associated with the convection speed of the amplified Klebanoff streaks, was found to be important.

Effects of Unforced Bounday Layer Transition on the Performance of a Two-Dimensional Hypersonic Inlet

2013 ◽  
Vol 275-277 ◽  
pp. 466-471
Author(s):  
Hai Feng Miao ◽  
Lv Rong Xie ◽  
Weng Xiao Chai
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Transition ◽  
Two Dimensional ◽  
Layer Transition ◽  
Recovery Coefficient ◽  
Static Pressure Distribution ◽  
Hypersonic Inlet ◽  
Flow Rate Increase ◽  
Compression Ramp ◽  
Onset Location

Numerical investigation was conducted on a typical two-dimensional hypersonic inlet to study the influence of unforced boundary layer transition affected by compression ramp geometric parameters on the inlet performance. The numerical results show that the transition onset location on the compression ramp can be delayed by filleting the ramp intersection, and also the inlet's performance obviously improves when the transition onset location is delayed. Compared with full turbulent situation, when the boundary layer transition occurs, the unstart of the inlet is significantly mitigated, the heat transfer rate on the compression ramp decreases, both the total pressure recovery coefficient and mass flow rate increase at both design and off-design points. But the static pressure distribution along the ramp is fairly independent of the varieties of boundary layer.

scholarly journals A Two-Dimensional Boundary-Layer Program for Turbine Airfoil Heat Transfer Calculation

1982 ◽  
Author(s):  
R. M. C. So ◽  
I. H. Edelfelt ◽  
E. Elovic ◽  
D. M. Kercher
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Wind Tunnel ◽  
Gas Turbines ◽  
Two Dimensional ◽  
Gas Temperature ◽  
Suction Surface ◽  
Pressure Surface ◽  
Dimensional Boundary ◽  
Wind Tunnel Data

A two-dimensional boundary-layer program has been developed for the calculation of flow and heat transfer around turbine airfoils. The program is capable of carrying out the calculation from the forward stagnation point, and can account for such effects as compressibility, high inlet gas temperature, streamwise pressure gradient, transition, streamline curvature and freestream turbulence. Three comparisons with recent measurements are carried out. Two are with idealized wind tunnel data. One is with cascade data obtained at high gas-to-wall temperature ratio of 2.56–2.85, which compares with a normal range of 1.4 to 2.4 for real gas turbines. Good agreement is obtained with the wind tunnel data. As for the cascade data, good correlation on the suction surface of the turbine airfoil is achieved. However, discrepancy on the pressure surface is observed and is attributed to the occurrence of local separation and reattachment in the actual flow.

Tip Leakage in a Centrifugal Impeller

1989 ◽  
Vol 111 (3) ◽  
pp. 244-249 ◽  
Author(s):  
T. Z. Farge ◽  
M. W. Johnson ◽  
T. M. A. Maksoud
Keyword(s):  
Boundary Layer ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Suction Side ◽  
Centrifugal Impeller ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Static Pressure Distribution ◽  
Impeller Outlet

The effects of tip leakage have been studied using a 1-m-dia shrouded impeller where a leakage gap is left between the inside of the shroud and the impeller blades. A comparison is made with results for the same impeller where the leakage gap is closed. The static pressure distribution is found to be almost unaltered by the tip leakage, but significant changes in the secondary velocities alter the size and position of the passage wake. Low-momentum fluid from the suction-side boundary layer of the measurement passage and tip leakage fluid from the neighboring passage contribute to the formation of a wake in the suction-side shroud corner region. The inertia of the tip leakage flow then moves this wake to a position close to the center of the shroud at the impeller outlet.

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