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David E Ashpis - One of the best experts on this subject based on the ideXlab platform.
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Effect of reynolds number and periodic unsteady wake flow condition on boundary layer development, separation, and intermittency behavior along the Suction Surface of a low pressure turbine blade
Journal of Turbomachinery, 2005Co-Authors: M T Schobeiri, B. Öztürk, David E AshpisAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and Reynolds number on boundary layer development, separation, reattachment, and the intermittency behavior along the Suction Surface of a low pressure turbine blade. Extensive unsteady boundary layer experiments were carried out at Reynolds numbers of 110,000 and 150,000 based on Suction Surface length and exit velocity. One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The analysis of the experimental data reveals details of boundary layer separation dynamics which is essential for understanding the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds numbers. To provide a complete picture of the transition process and separation dynamics, extensive intermittency analysis was conducted. Ensemble-averaged maximum and minimum intermittency functions were determined, leading to the relative intermittency function. In addition, the detailed intermittency analysis was aimed at answering the question as to whether the relative intermittency of a separated flow fulfills the universality criterion.
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intermittent behavior of the separated boundary layer along the Suction Surface of a low pressure turbine blade under periodic unsteady flow conditions
ASME Turbo Expo 2005: Power for Land Sea and Air, 2005Co-Authors: B Ozturk, M T Schobeiri, David E AshpisAbstract:The paper experimentally and theoretically studies the effects of periodic unsteady wake flow and aerodynamic characteristics on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experiments were carried out at Reynolds number of 110,000 (based on Suction Surface length and exit velocity). For one steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, intermittency behavior were experimentally and theoretically investigated. The current investigation attempts to extend the intermittency unsteady boundary layer transition model developed in previously to the LPT cases, where separation occurs on the Suction Surface at a low Reynolds number. The results of the unsteady boundary layer measurements and the intermittency analysis were presented in the ensemble-averaged, and contour plot forms. The analysis of the boundary layer experimental data with the flow separation, confirms the universal character of the relative intermittency function which is described by a Gausssian function.Copyright © 2005 by ASME
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Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Re-Attachment Along the Suction Surface of a Low Pressure Turbine Blade
Volume 3: Turbo Expo 2005 Parts A and B, 2005Co-Authors: B. Öztürk, M T Schobeiri, David E AshpisAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on Suction Surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, Surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the Suction Surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re = 110,000.Copyright © 2005 by ASME
M T Schobeiri - One of the best experts on this subject based on the ideXlab platform.
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Effect of Turbulence Intensity and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Reattachment Along the Suction Surface of a Low-Pressure Turbine Blade
Journal of Fluids Engineering, 2006Co-Authors: B. Öztürk, M T SchobeiriAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on Suction Surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, Surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the Suction Surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re=110,000.
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Effect of Turbulence Intensity and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Re-Attachment Over the Separation Bubble Along the Suction Surface of a Low Pressure Turbine Blade
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: B. Öztürk, M T SchobeiriAbstract:The paper experimentally investigates the individual and combined effects of periodic unsteady wake flows and freestream turbulence intensity (FSTI) on flow separation along the Suction Surface of a low pressure turbine blade. The experiments were carried out at a Reynolds number of 110,000 based on the Suction Surface length and the cascade exit velocity. The experimental matrix includes freestream turbulence intensities of 1.9%, 3.0%, 8.0%, 13.0% and three different unsteady wake frequencies with the steady inlet flow as the reference configuration. Detailed boundary layer measurements are performed along the Suction Surface of a highly loaded turbine blade with a separation zone. Particular attention is paid to the aerodynamic behavior of the separation zone at different FSTIs at steady and periodic unsteady flow conditions. The objective of the research is (a) to quantify the effect of FSTIs on the dynamics of the separation bubble at steady inlet flow condition, and (b) to investigate the combined effects of FSTI and the unsteady wake flow on the behavior of the separation bubble. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University.Copyright © 2006 by ASME
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Effect of reynolds number and periodic unsteady wake flow condition on boundary layer development, separation, and intermittency behavior along the Suction Surface of a low pressure turbine blade
Journal of Turbomachinery, 2005Co-Authors: M T Schobeiri, B. Öztürk, David E AshpisAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and Reynolds number on boundary layer development, separation, reattachment, and the intermittency behavior along the Suction Surface of a low pressure turbine blade. Extensive unsteady boundary layer experiments were carried out at Reynolds numbers of 110,000 and 150,000 based on Suction Surface length and exit velocity. One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The analysis of the experimental data reveals details of boundary layer separation dynamics which is essential for understanding the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds numbers. To provide a complete picture of the transition process and separation dynamics, extensive intermittency analysis was conducted. Ensemble-averaged maximum and minimum intermittency functions were determined, leading to the relative intermittency function. In addition, the detailed intermittency analysis was aimed at answering the question as to whether the relative intermittency of a separated flow fulfills the universality criterion.
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intermittent behavior of the separated boundary layer along the Suction Surface of a low pressure turbine blade under periodic unsteady flow conditions
ASME Turbo Expo 2005: Power for Land Sea and Air, 2005Co-Authors: B Ozturk, M T Schobeiri, David E AshpisAbstract:The paper experimentally and theoretically studies the effects of periodic unsteady wake flow and aerodynamic characteristics on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experiments were carried out at Reynolds number of 110,000 (based on Suction Surface length and exit velocity). For one steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, intermittency behavior were experimentally and theoretically investigated. The current investigation attempts to extend the intermittency unsteady boundary layer transition model developed in previously to the LPT cases, where separation occurs on the Suction Surface at a low Reynolds number. The results of the unsteady boundary layer measurements and the intermittency analysis were presented in the ensemble-averaged, and contour plot forms. The analysis of the boundary layer experimental data with the flow separation, confirms the universal character of the relative intermittency function which is described by a Gausssian function.Copyright © 2005 by ASME
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Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Re-Attachment Along the Suction Surface of a Low Pressure Turbine Blade
Volume 3: Turbo Expo 2005 Parts A and B, 2005Co-Authors: B. Öztürk, M T Schobeiri, David E AshpisAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on Suction Surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, Surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the Suction Surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re = 110,000.Copyright © 2005 by ASME
Richard Rivir - One of the best experts on this subject based on the ideXlab platform.
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Measurements in a Turbine Cascade Flow Under Ultra Low Reynolds Number Conditions
Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration, 2001Co-Authors: Kenneth W. Van Treuren, Terrence W Simon, Marc Von Koller, Aaron R. Byerley, James W. Baughn, Richard RivirAbstract:With the new generation of gas turbine engines, low Reynolds number flows have become increasingly important. Designers must properly account for transition from laminar to turbulent flow and separation of the flow from the Suction Surface, which is strongly dependent upon transition. Of interest to industry are Reynolds numbers based upon Suction Surface length and flow exit velocity below 150,000 and as low as 25,000. In this paper, the extreme low end of this Reynolds number range is documented by way of pressure distributions, loss coefficients and identification of separation zones. Reynolds numbers of 25,000 and 50,000 and with 1% and 8–9% turbulence intensity of the approach flow (Free Stream Turbulence Intensity, FSTI) were investigated.At 25,000 Reynolds number and low FSTI, the Suction Surface displayed a strong and steady separation region. Raising the turbulence intensity resulted in a very unsteady separation region of nearly the same size on the Suction Surface. Vortex generators were added to the Suction Surface, but they appeared to do very little at this Reynolds number.At the higher Reynolds number of 50,000, the low-FSTI case was strongly separated on the downstream portion of the Suction Surface. The separation zone was eliminated when the turbulence level was increased to 8–9%. Vortex generators were added to the Suction Surface of the low-FSTI case. In this instance, the vortices were able to provide the mixing needed to reestablish flow attachment.This paper shows that massive separation at very low Reynolds numbers (25,000) is persistent, in spite of elevated FSTI and added vortices. However, at a higher Reynolds number, there is opportunity for flow reattachment either with elevated freestream turbulence or with added vortices. This may be the first documentation of flow behavior at such low Reynolds numbers. Though undesirable to operate under these conditions, it is important to know what to expect and how performance may be improved if such conditions are unavoidable.© 2001 ASME
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Measurements in a Turbine Cascade Flow Under Ultra Low Reynolds Number Conditions
Journal of Turbomachinery, 2001Co-Authors: Kenneth W. Van Treuren, Terrence W Simon, Marc Von Koller, Aaron R. Byerley, James W. Baughn, Richard RivirAbstract:With the new generation of gas turbine engines, low Reynolds number flows have become increasingly important. Designers must properly account for transition from laminar to turbulent flow and separation of the flow from the Suction Surface, which is strongly dependent upon transition. Of interest to industry are Reynolds numbers based upon Suction Surface length and flow exit velocity below 150,000 and as low as 25,000. In this paper, the extreme low end of this Reynolds number range is documented by way of pressure distributions, loss coefficients, and identification of separation zones. Reynolds numbers of 25,000 and 50,000 and with 1 percent and 8-9 percent turbulence intensity of the approach flow (free-stream turbulence intensity, FSTI) were investigated. At 25,000 Reynolds number and low FSTI, the Suction Surface displayed a strong and steady separation region. Raising the turbulence intensity resulted in a very unsteady separation region of nearly the same size on the Suction Surface. Vortex generators were added to the Suction Surface, but they appeared to do very little at this Reynolds number. At the higher Reynolds number of 50,000, the low-FSTI case was strongly separated on the downstream portion of the Suction Surface. The separation zone was eliminated when the turbulence level was increased to 8-9 percent. Vortex generators were added to the Suction Surface of the low-FSTI case. In this instance, the vortices were able to provide the mixing needed to re-establish flow attachment. This paper shows that massive separation at very low Reynolds numbers (25,000) is persistent, in spite of elevated FSTI and added vortices. However, at a higher Reynolds number, there is opportunity for flow reattachment either with elevated free-stream turbulence or with added vortices. This may be the first documentation of flow behavior at such low Reynolds numbers. Although it is undesirable to operate under these conditions, it is important to know what to expect and how performance may be improved if such conditions are unavoidable.
Sumanta Acharya - One of the best experts on this subject based on the ideXlab platform.
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Vane Suction Surface Heat Transfer in Regions of Secondary Flows: The Influence of Turbulence Level, Reynolds Number and the Endwall Boundary Condition
Journal of Turbomachinery, 2017Co-Authors: Justin E. Varty, L. W. Soma, Forrest E. Ames, Sumanta AcharyaAbstract:Secondary flows in vane passages sweep off the endwall and onto the Suction Surface at a location typically close to the throat. These endwall/vane junction flows often have an immediate impact on heat transfer in this region and also move any film cooling off the affected region of the vane. The present paper documents the impact of secondary flows on Suction Surface heat transfer acquired over a range of turbulence levels (0.7–17.4%) and a range of exit chord Reynolds numbers (500,000–2,000,000). Heat transfer data are acquired with both an unheated endwall boundary condition and a heated endwall boundary condition. The vane design includes an aft loaded Suction Surface and a large leading edge diameter. The unheated endwall boundary condition produces initially very high heat transfer levels due to the thin thermal boundary layer starting at the edge of heating. This unheated starting length effect quickly falls off with the thermal boundary layer growth as the secondary flow sweeps up onto the vane Suction Surface. The heat transfer visualization for the heated endwall condition shows no initial high heat transfer level near the edge of heating on the vane. The heat transfer level in the region affected by the secondary flows is largely uniform, except for a notable depression in the affected region. This heat transfer depression is believed due to an upwash region generated above the separation line of the passage vortex, likely in conjunction with the counter rotating Suction leg of the horseshoe vortex. The extent and definition of the secondary flow-affected region on the Suction Surface are clearly evident at lower Reynolds numbers and lower turbulence levels when the Suction Surface flow is largely laminar. The heat transfer in the plateau region has a magnitude similar to a turbulent boundary layer. However, the location and extent of this secondary flow-affected region are less perceptible at higher turbulence levels where transitional or turbulent flow is present. Also, aggressive mixing at higher turbulence levels serves to smooth out discernable differences in the heat transfer due to the secondary flows.
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Vane Suction Surface Heat Transfer in Regions of Secondary Flows: The Influence of Turbulence Level, Reynolds Number and the Endwall Boundary Condition
Volume 5A: Heat Transfer, 2017Co-Authors: Justin E. Varty, L. W. Soma, Forrest E. Ames, Sumanta AcharyaAbstract:Secondary flows in vane passages sweep off the endwall and onto the Suction Surface at a location typically close to the throat. These endwall/vane junction flows often have an immediate impact on heat transfer in this region and also move any film cooling off the affected region of the vane. The present paper documents the impact of secondary flows on Suction Surface heat transfer acquired over a range of turbulence levels (0.7% through 17.4%) and a range of exit chord Reynolds numbers (500,000 through 2,000,000). Heat transfer data are acquired with both an unheated endwall boundary condition and a heated endwall boundary condition. The vane design includes an aft loaded Suction Surface and a large leading edge diameter. The unheated endwall boundary condition produces initially very high heat transfer levels due to the thin thermal boundary layer starting at the edge of heating. This unheated starting length effect quickly falls off with the thermal boundary layer growth as the secondary flow sweeps up onto the vane Suction Surface. The heat transfer visualization for the heated endwall condition shows no initial high heat transfer level near the edge of heating on the vane. The heat transfer level in the region affected by the secondary flows is largely uniform, except for a notable depression in the affected region. This heat transfer depression is believed due to an upwash region generated above the separation line of the passage vortex, likely in conjunction with the counter rotating Suction leg of the horseshoe vortex. The extent and definition of the secondary flow affected region on the Suction Surface is clearly evident at lower Reynolds numbers and lower turbulence levels when the Suction Surface flow is largely laminar. The heat transfer in the plateau region has a magnitude similar to a turbulent boundary layer. However, the location and extent of this secondary flow affected region is less perceptible at higher turbulence levels where transitional or turbulent flow is present. Also, aggressive mixing at higher turbulence levels serves to smooth out discernable differences in the heat transfer due to the secondary flows.
B. Öztürk - One of the best experts on this subject based on the ideXlab platform.
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Effect of Turbulence Intensity and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Reattachment Along the Suction Surface of a Low-Pressure Turbine Blade
Journal of Fluids Engineering, 2006Co-Authors: B. Öztürk, M T SchobeiriAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on Suction Surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, Surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the Suction Surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re=110,000.
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Effect of Turbulence Intensity and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Re-Attachment Over the Separation Bubble Along the Suction Surface of a Low Pressure Turbine Blade
Volume 6: Turbomachinery Parts A and B, 2006Co-Authors: B. Öztürk, M T SchobeiriAbstract:The paper experimentally investigates the individual and combined effects of periodic unsteady wake flows and freestream turbulence intensity (FSTI) on flow separation along the Suction Surface of a low pressure turbine blade. The experiments were carried out at a Reynolds number of 110,000 based on the Suction Surface length and the cascade exit velocity. The experimental matrix includes freestream turbulence intensities of 1.9%, 3.0%, 8.0%, 13.0% and three different unsteady wake frequencies with the steady inlet flow as the reference configuration. Detailed boundary layer measurements are performed along the Suction Surface of a highly loaded turbine blade with a separation zone. Particular attention is paid to the aerodynamic behavior of the separation zone at different FSTIs at steady and periodic unsteady flow conditions. The objective of the research is (a) to quantify the effect of FSTIs on the dynamics of the separation bubble at steady inlet flow condition, and (b) to investigate the combined effects of FSTI and the unsteady wake flow on the behavior of the separation bubble. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University.Copyright © 2006 by ASME
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Effect of reynolds number and periodic unsteady wake flow condition on boundary layer development, separation, and intermittency behavior along the Suction Surface of a low pressure turbine blade
Journal of Turbomachinery, 2005Co-Authors: M T Schobeiri, B. Öztürk, David E AshpisAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and Reynolds number on boundary layer development, separation, reattachment, and the intermittency behavior along the Suction Surface of a low pressure turbine blade. Extensive unsteady boundary layer experiments were carried out at Reynolds numbers of 110,000 and 150,000 based on Suction Surface length and exit velocity. One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The analysis of the experimental data reveals details of boundary layer separation dynamics which is essential for understanding the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds numbers. To provide a complete picture of the transition process and separation dynamics, extensive intermittency analysis was conducted. Ensemble-averaged maximum and minimum intermittency functions were determined, leading to the relative intermittency function. In addition, the detailed intermittency analysis was aimed at answering the question as to whether the relative intermittency of a separated flow fulfills the universality criterion.
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Effect of Reynolds Number and Periodic Unsteady Wake Flow Condition on Boundary Layer Development, Separation, and Re-Attachment Along the Suction Surface of a Low Pressure Turbine Blade
Volume 3: Turbo Expo 2005 Parts A and B, 2005Co-Authors: B. Öztürk, M T Schobeiri, David E AshpisAbstract:The paper experimentally studies the effects of periodic unsteady wake flow and different Reynolds numbers on boundary layer development, separation and re-attachment along the Suction Surface of a low pressure turbine blade. The experimental investigations were performed on a large scale, subsonic unsteady turbine cascade research facility at Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. The experiments were carried out at Reynolds numbers of 110,000 and 150,000 (based on Suction Surface length and exit velocity). One steady and two different unsteady inlet flow conditions with the corresponding passing frequencies, wake velocities, and turbulence intensities were investigated. The reduced frequencies chosen cover the operating range of LP turbines. In addition to the unsteady boundary layer measurements, Surface pressure measurements were performed. The inception, onset, and the extent of the separation bubble information collected from the pressure measurements were compared with the hot wire measurements. The results presented in ensemble-averaged, and the contour plot forms help to understand the physics of the separation phenomenon under periodic unsteady wake flow and different Reynolds number. It was found that the Suction Surface displayed a strong separation bubble for these three different reduced frequencies. For each condition, the locations defining the separation bubble were determined carefully analyzing and examining the pressure and mean velocity profile data. The location of the boundary layer separation was dependent of the Reynolds number. It is observed that starting point of the separation bubble and the re-attachment point move further downstream by increasing Reynolds number from 110,000 to 150,000. Also, the size of the separation bubble is smaller when compared to that for Re = 110,000.Copyright © 2005 by ASME
