A Quasi-Unsteady Study on Wake Interaction of Turbine Stator and Rotor Cascades

1995 ◽  
Vol 117 (4) ◽  
pp. 553-561 ◽  
Author(s):  
A. Yamamoto ◽  
R. Murao ◽  
Y. Suzuki ◽  
Y. Aoi
Keyword(s):  
Suction Side ◽  
Secondary Flows ◽  
Relative Location ◽  
Flow Measurements ◽  
Tip Leakage ◽  
Turbine Stator ◽  
Wake Interaction ◽  
In Series ◽  
Cascade Interaction ◽  
Made In

Detailed flow measurements were made to study cascade interaction of turbine stator and rotor, using two linear cascades installed in series. The upstream cascade was moved to several places in the cascade pitchwise direction in order to change the relative location between the two cascades, and measurements were made in the downstream cascade. The result shows that the net total pressure loss generated in the downstream cascade becomes maximum when wakes of the upstream cascade pass the suction side of the downstream cascade passage, while the tip leakage loss generated in the downstream cascade does not change with the relative location of the cascades. The upstream cascade wakes interact with the secondary flows and most strongly with the endwall flow in the downstream cascade passage, making the loss distributions in the cascades fairly unsteady.

A Quasi Unsteady Study on Wake Interaction of Turbine Stator and Rotor Cascades

1994 ◽  
Author(s):  
Atsumasa Yamamoto ◽  
Rin-ichi Murao ◽  
Yuji Suzuki ◽  
Yoshihiro Aoi
Keyword(s):  
Suction Side ◽  
Secondary Flows ◽  
Relative Location ◽  
Flow Measurements ◽  
Tip Leakage ◽  
Turbine Stator ◽  
Wake Interaction ◽  
In Series ◽  
Cascade Interaction ◽  
Made In

Detailed flow measurements were made to study cascade interaction of turbine stator and rotor, by using two linear cascades installed in series. The upstream cascade was traversed at several times in the cascade pitchwise direction in order to change the relative location between the two cascades, and measurements were made in the downstream cascade. The result shows that the net total pressure loss generated in the downstream cascade becomes maximum when wakes of the upstream cascade pass the suction side of the downstream cascade passage, while the tip leakage loss generated in the downstream cascade does not change with the relative location th cascades. The upstreaof born cascade wakes interact with the secondary flows, and most strongly with the endwall flow in the downstream cascade passage, making the loss distributions in both cascades fairly unsteady.

Production and Development of Secondary Flows and Losses Within a Three Dimensional Turbine Stator Cascade

1985 ◽  
Author(s):  
A. Yamamoto ◽  
R. Yanagi
Keyword(s):  
Three Dimensional ◽  
Quantitative Information ◽  
Secondary Flows ◽  
Suction Surface ◽  
Trailing Edge ◽  
Loss Mechanism ◽  
Flow Measurements ◽  
Aerodynamic Loss ◽  
Vortical Flows ◽  
Turbine Stator

Using five-hole pitot tubes, detailed flow measurements were made before, within and after a low-speed three-dimensional turbine stator blade row to obtain quantitative information on the aerodynamic loss mechanism. Qualitative flow visualization tests and endwall static pressure measurements were also made. An analysis of the tests revealed that many vortical flows promote loss generation. Within a large part of the cascade, a major loss process could be explained simply as the migration of boundary layer low energy fluids from surrounding walls (endwalls and blade surfaces) to the blade suction surface near the trailing edge. On the other hand, complexity exists after the cascade and in the vortical flows near the trailing edge. The strong trailing shedding vortices affect upstream flow fields within the cascade. Detailed flow surveys within the cascade under the effects of blade tip leakage flows are also included.

scholarly journals The Effect of Blade Tip Geometry on the Tip Leakage Flow in Axial Turbine Cascades

1991 ◽  
Author(s):  
F. J. G. Heyes ◽  
H. P. Hodson ◽  
G. M. Dailey
Keyword(s):  
Discharge Coefficient ◽  
Suction Side ◽  
Generation Process ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip ◽  
Overall Performance ◽  
Turbine Cascades ◽  
Made In ◽  
Blade Tip Geometry

The phenomenon of tip leakage has been studied in two linear cascades of turbine blades.The investigation includes an examination of the performance of the cascades with a variety of tip geometries. The effects of using plain tips, suction side squealers and pressure side squealers are reported. Traverses of the exit flow field were made in order to determine the overall performance. A method of calculating the tip discharge coefficients for squealer geometries is put forward. In linking the tip discharge coefficient and cascade losses a procedure for predicting the relative performance of tip geometries is developed. The model is used to examine the results obtained using the different tip treatments and to highlight the important aspects of the loss generation process.

Evaluation of the Interaction Losses in a Transonic Turbine HP Rotor/LP Vane Configuration

1997 ◽  
Vol 119 (1) ◽  
pp. 68-76 ◽  
Author(s):  
I. K. Jennions ◽  
J. J. Adamczyk
Keyword(s):  
Three Dimensional ◽  
Numerical Approach ◽  
Secondary Flows ◽  
Tip Leakage ◽  
Leakage Flows ◽  
Trade Offs ◽  
Aerodynamic Interaction ◽  
Transonic Turbine ◽  
Tip Leakage Flows ◽  
Made In

Transonic turbine rotors produce shock waves, wakes, tip leakage flows, and other secondary flows that the downstream stators have to ingest. While the physics of wake ingestion and shock interaction have been studied quite extensively, few ideas for reducing the aerodynamic interaction losses have been forthcoming. This paper aims to extend previously reported work performed by GE Aircraft Engines in this area. It reports on both average-passage (steady) and unsteady three-dimensional numerical simulations of a candidate design to shed light on the interaction loss mechanisms and evaluate the design. The results from these simulations are first shown against test data for a baseline configuration to engender confidence in the numerical approach. Simulations with the proposed newly designed rotor are then performed to show the trade-offs that are being made in such designs. The new rotor does improve the overall efficiency of the group and physical explanations are presented based on examining entropy production.

The Development of Wake Flow in a Centrifugal Impeller

1980 ◽  
Vol 102 (2) ◽  
pp. 382-389 ◽  
Author(s):  
M. W. Johnson ◽  
J. Moore
Keyword(s):  
Three Dimensional ◽  
Suction Side ◽  
Secondary Flows ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Three Dimensional Flow ◽  
Cross Sectional ◽  
Flow Measurements ◽  
Compressor Impeller ◽  
Rotating Impeller

Three-dimensional flow, leading to the formation and the growth of a wake in a centrifugal impeller, has been studied. Results of flow measurements in a 1 m dia, shrouded, centrifugal compressor impeller running at 500 rpm are presented. Relative velocities and rotary stagnation pressures (p* = p + 1/2ρW2 − 1/2ρω2r2) were measured, on five cross-sectional planes between the inlet and outlet of the impeller, using pressure probes which were traversed within the rotating impeller passage. Particular attention was given to the convection of low p* fluid by secondary flows and to the formation of the wake in the shroud/suction-side corner region of the passage.

Control of Rotor Tip Leakage Through Cooling Injection From the Casing in a High-Work Turbine

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Thomas Behr ◽  
Anestis I. Kalfas ◽  
Reza S. Abhari
Keyword(s):  
Experimental Investigation ◽  
Secondary Flow ◽  
Mass Flow ◽  
Turbulence Intensity ◽  
Suction Side ◽  
Secondary Flows ◽  
Axial Position ◽  
Current Investigation ◽  
Tip Leakage ◽  
Cooling Air

This paper presents an experimental investigation of a novel approach for controlling the rotor tip leakage and secondary flow by injecting cooling air from the stationary casing onto the rotor tip. It contains a detailed analysis of the unsteady flow interaction between the injected air and the flow in the rotor tip region and its impact on the rotor secondary flow structures. The experimental investigation has been conducted on a one-and-1/2-stage, unshrouded turbine, which has been especially designed and built for the current investigation. The turbine test case models a highly loaded, high pressure gas turbine stage. Measurements conducted with a two-sensor fast-response aerodynamic probe have provided data describing the time-resolved behavior of flow angles and pressures, as well as turbulence intensity in the exit plane of the rotor. Cooling air has been injected in the circumferential direction at a 30 deg angle from the casing tangent, opposing the rotor turning direction through a circumferential array of ten equidistant holes per rotor pitch. Different cooling air injection configurations have been tested. Injection parameters such as mass flow, axial position, and size of the holes have been varied to see the effect on the rotor tip secondary flows. The results of the current investigation show that with the injection, the size and the turbulence intensity of the rotor tip leakage vortex and the rotor tip passage vortex reduce. Both vortices move toward the tip suction side corner of the rotor passage. With an appropriate combination of injection mass flow rate and axial injection position, the isentropic efficiency of the stage was improved by 0.55 percentage points.

Flow Measurements in a Human Femoral Artery Model With Reverse Lumen Curvature

1988 ◽  
Vol 110 (4) ◽  
pp. 300-309 ◽  
Author(s):  
L. H. Back ◽  
M. R. Back ◽  
E. Y. Kwack ◽  
D. W. Crawford
Keyword(s):  
Steady Flow ◽  
Femoral Artery ◽  
Flow Simulation ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Reverse Direction ◽  
Flow Measurements ◽  
Left Femoral Artery ◽  
Lesion Localization ◽  
Made In

Flow visualization and wall pressure measurements were made in a smooth reverse curvature model that conformed to the gentle “s” shape of a left femoral artery angiogram of a patient in a clinical trial. Observed lesion localization at the inner (lesser) curvatures appeared to be associated with secondary flows in the wall vicinity directed toward the inner curvatures that tended to reverse direction in the flow entering the reverse curvature region. Moderate flow resistance increases of about 20 percent above the Poiseuille flow relation were found at the higher physiological Reynolds numbers Re above about 600–700 and thus Dean numbers for steady flow. For pulsatile flow simulation, flow resistances did not increase up to the largest Re of 470 tested. Apparently, the large variations in velocity during the cardiac cycle disrupted the stronger secondary flow patterns observed at the higher Reynolds numbers for steady flow.

The Effect of Blade Tip Geometry on the Tip Leakage Flow in Axial Turbine Cascades

1992 ◽  
Vol 114 (3) ◽  
pp. 643-651 ◽  
Author(s):  
F. J. G. Heyes ◽  
H. P. Hodson ◽  
G. M. Dailey
Keyword(s):  
Turbine Blades ◽  
Suction Side ◽  
Generation Process ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip ◽  
Overall Performance ◽  
Turbine Cascades ◽  
Made In ◽  
Blade Tip Geometry

The phenomenon of tip leakage has been studied in two linear cascades of turbine blades. The investigation includes an examination of the performance of the cascades with a variety of tip geometries. The effects of using plain tips, suction side squealers, and pressure side squealers are reported. Traverses of the exit flow field were made in order to determine the overall performance. A method of calculating the tip discharge coefficients for squealer geometries is put forward. In linking the tip discharge coefficient and cascade losses, a procedure for predicting the relative performance of tip geometries is developed. The model is used to examine the results obtained using the different tip treatments and to highlight the important aspects of the loss generation process.

scholarly journals Evaluation of the Interaction Losses in a Transonic Turbine HP Rotor / LP Vane Configuration

1995 ◽  
Author(s):  
I. K. Jennions ◽  
J. J. Adamczyk
Keyword(s):  
Numerical Approach ◽  
Secondary Flows ◽  
Tip Leakage ◽  
Leakage Flows ◽  
Trade Offs ◽  
Aerodynamic Interaction ◽  
Transonic Turbine ◽  
Tip Leakage Flows ◽  
Shed Light ◽  
Made In

Transonic turbine rotors produce shock waves, wakes, tip leakage flows and other secondary flows that the downstream stators have to ingest. While the physics of wake ingestion and shock interaction have been studied quite extensively, few ideas for reducing the aerodynamic interaction losses have been forthcoming. This paper aims to extend previously reported work performed by GE Aircraft Engines in this area. It reports on both average-passage (steady) and unsteady 3D numerical simulations of a candidate design to shed light on the interaction loss mechanisms and evaluate the design. The results from these simulations are first shown against test data for a Baseline configuration to engender confidence in the numerical approach. Simulations with the proposed newly designed rotor are then performed to show the trade-offs that are being made in such designs. The new rotor does improve the overall efficiency of the group and physical explanations are presented based on examining entropy production.

Control of Rotor Tip Leakage Through Cooling Injection From the Casing in a High-Work Turbine: Experimental Investigation

2007 ◽  
Author(s):  
Thomas Behr ◽  
Anestis I. Kalfas ◽  
Reza S. Abhari
Keyword(s):  
Experimental Investigation ◽  
Secondary Flow ◽  
Turbulence Intensity ◽  
Suction Side ◽  
Secondary Flows ◽  
Axial Position ◽  
Pressure Probe ◽  
Current Investigation ◽  
Tip Leakage ◽  
Cooling Air

This paper presents an experimental investigation of a novel approach for controlling the rotor tip secondary flow by injecting cooling air from the stationary casing onto the rotor tip. It contains a detailed analysis of the unsteady flow interaction between the injected air and the flow in the rotor tip region and its impact on the rotor secondary flow structures. The experimental investigation has been conducted on a one-and-1/2-stage, unshrouded turbine, which has been especially designed and built for the current investigation. The turbine test case models a highly-loaded, high-pressure gas turbine stage. Measurements conducted with a two-sensor fast response pressure probe (FRAP) have provided data describing the time-resolved behavior of flow angles and pressures, as well as turbulence intensity in the exit plane of the rotor. Cooling air has been injected in circumferential direction at a 30° angle from the casing tangent, opposing the rotor turning direction through a circumferential array of 10 equidistant holes per rotor pitch. Different cooling air injection configurations have been tested. Injection parameters such as massflow, axial position and size of the holes have been varied to see the effect on the rotor tip secondary flows. The results of the current investigation show that with the injection, the size and the turbulence intensity of the rotor tip leakage vortex and the rotor tip passage vortex reduce. Both vortices move towards the tip suction side corner of the rotor passage. With an appropriate combination of injection massflow rate and axial injection position the isentropic efficiency of the stage was improved by 0.55 percent points.

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