scholarly journals Unsteady Wake Effects on Boundary Layer Transition and Heat Transfer Characteristics of a Turbine Blade

1998 ◽  
Author(s):  
M. T. Schobeiri ◽  
P. Chakka ◽  
K. Pappu
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbine Blade ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Transition Model ◽  
Heat Transfer Characteristics ◽  
Layer Transition ◽  
Unsteady Wake ◽  
Unsteady Wake Flow

Effect of unsteady wakes on aerodynamic and heat transfer characteristics of a turbine blade in a cascade were analyzed both experimentally and theoretically. Comprehensive aerodynamic data were collected for different wake passing frequencies that are typical of turbomachinery. Hot-wire probes were used for collection of boundary layer data on suction and pressure surfaces of the turbine blade. Heat transfer measurements were made using steady liquid crystal techniques. Boundary layer data were analyzed through intermittency function to get insight into the transition process under unsteady wake flow conditions. The experimental and theoretical results presented in this paper confirm the general validity of the unsteady boundary layer transition model developed by Chakka and Schobeiri (1997). This model is based on a relative intermittency function, which accounts for the effects of periodic unsteady wake flow on the boundary layer transition. Three distinct quantities are identified as primarily responsible for the transition of an unsteady boundary layer. These quantities, which exhibit the basis of the transition analysis presented in this paper, are: (1) relative intermittency, (2) maximum intermittency, and (3) minimum intermittency. To validate the developed transition model, it is implemented in an existing boundary layer code, and the resulting heat transfer coefficients are compared with the experimental data.

Modeling Unsteady Boundary Layer Transition on a Curved Plate Under Periodic Unsteady Flow Conditions: Aerodynamic and Heat Transfer Investigations

1999 ◽  
Vol 121 (1) ◽  
pp. 88-97 ◽  
Author(s):  
P. Chakka ◽  
M. T. Schobeiri
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Unsteady Flow ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Transition Model ◽  
Unsteady Boundary Layer ◽  
Layer Transition ◽  
Unsteady Wake ◽  
Unsteady Wake Flow

A boundary layer transition model is developed that accounts for the effects of periodic unsteady wake flow on the boundary layer transition. To establish the model, comprehensive unsteady boundary layer and heat transfer experimental investigations are conducted. The experiments are performed on a curved plate at zero-streamwise pressure gradient under periodic unsteady wake flow, where the frequency of the periodic unsteady flow is varied. The analysis of the time-dependent velocities, turbulence intensities, and turbulence intermittencies has identified three distinct quantities as primarily responsible for the transition of an unsteady boundary layer. These quantities, which exhibit the basis of the transition model presented in this paper, are: (1) relative intermittency, (2) maximum intermittency, and (3) minimum intermittency. To validate the developed transition model, it is implemented in an existing boundary layer code, and the resulting velocity profiles and the heat transfer coefficients are compared with the experimental data.

scholarly journals Modeling Unsteady Boundary Layer Transition on a Curved Plate Under Periodic Unsteady Flow Conditions: Aerodynamic and Heat Transfer Investigations

1997 ◽  
Author(s):  
P. Chakka ◽  
M. T. Schobeiri
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Unsteady Flow ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Transition Model ◽  
Unsteady Boundary Layer ◽  
Layer Transition ◽  
Unsteady Wake ◽  
Unsteady Wake Flow

A boundary layer transition model is developed that accounts for the effects of periodic unsteady wake flow on the boundary layer transition. To establish the model, comprehensive unsteady boundary layer and heat transfer experimental investigations are conducted. The experiments are performed on a curved plate at zero-streamwise pressure gradient under periodic unsteady wake flow, where the frequency of the periodic unsteady flow is varied. The analysis of the time dependent velocities, turbulence intensities, and turbulence intermittencies has identified three distinct quantities as primarily responsible for the transition of an unsteady boundary layer. These quantities, which exhibit the basis of the transition model presented in this paper, are: (1) relative intermittency, (2) maximum intermittency, and (3) minimum intermittency. To validate the developed transition model, it is implemented in an existing boundary layer code, and the resulting velocity profiles and the heat transfer coefficients are compared with the experimental data.

scholarly journals Advances in Unsteady Boundary Layer Transition Research, Part I: Theory and Modeling

2003 ◽  
Vol 9 (1) ◽  
pp. 1-9
Author(s):  
M. T. Schobeiri ◽  
L. Wright
Keyword(s):  
Boundary Layer ◽  
Turbine Blades ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Test Facility ◽  
Transition Model ◽  
Unsteady Boundary Layer ◽  
Layer Transition ◽  
Unsteady Wake ◽  
Unsteady Wake Flow

This two-part article presents recent advances in boundary layer research that deal with the unsteady boundary layer transition modeling and its validation. A new unsteady boundary layer transition model was developed based on a universal unsteady intermittency function. It accounts for the effects of periodic unsteady wake flow on the boundary layer transition. To establish the transition model, an inductive approach was implemented; the approach was based on the results of comprehensive experimental and theoretical studies of unsteady wake flow and unsteady boundary layer flow. The experiments were performed on a curved plate at a zero streamwise pressure gradient under a periodic unsteady wake flow, where the frequency of the periodic unsteady flow was varied. To validate the model, systematic experimental investigations were performed on the suction and pressure surfaces of turbine blades integrated into a high-subsonic cascade test facility, which was designed for unsteady boundary layer investigations. The analysis of the experiment's results and comparison with the model's prediction confirm the validity of the model and its ability to predict accurately the unsteady boundary layer transition.

Intermittency Based Unsteady Boundary Layer Transition Modeling: Implementation Into Navier-Stokes Equations

2005 ◽  
Author(s):  
M. T. Schobeiri
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Navier Stokes ◽  
Transition Model ◽  
Unsteady Boundary Layer ◽  
Layer Transition ◽  
Navier Stokes Equations ◽  
Unsteady Wake

This paper presents recent advances in boundary layer research that deal with an intermittency based unsteady boundary layer transition model and its implementation into the Reynolds averaged Navier-Stokes equations (RANS). RANS equations are conditioned to include the ensemble averaged unsteady intermittency function. The unsteady boundary layer transition model is based on a universal unsteady intermittency function developed earlier. It accounts for the effects of periodic unsteady wake flow on the boundary layer transition. The transition model is the result of an inductive approach analyzing the unsteady data obtained by experiments on a curved plate at zero-streamwise pressure gradient under periodic unsteady wake flow. To validate this model, systematic experimental investigations were conducted on the suction and pressure surfaces of turbine blades that were integrated into a turbine cascade test facility, which was designed for unsteady boundary layer investigations. This model is implemented into the above mentioned conditioned RANS-equations and calculation results are presented.

scholarly journals Advances in Unsteady Boundary Layer Transition Research, Part II: Experimental Verification

2003 ◽  
Vol 9 (1) ◽  
pp. 11-22 ◽  
Author(s):  
M. T. Schobeiri ◽  
L. Wright
Keyword(s):  
Boundary Layer ◽  
Turbine Blades ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Test Facility ◽  
Experimental Investigations ◽  
Unsteady Boundary Layer ◽  
Layer Transition ◽  
Unsteady Wake ◽  
Unsteady Wake Flow

This two-part article presents recent advances in boundary layer research into the unsteady boundary layer transition modeling and its validation. This, Part II, deals with the results of an inductive approach based on comprehensive experimental and theoretical studies of unsteady wake flow and unsteady boundary layer flow. The experiments were performed on a curved plate at a zero streamwise pressure gradient under periodic unsteady wake flow, in which the frequency of the periodic unsteady flow was varied. To validate the model, systematic experimental investigations were performed on the suction and pressure surfaces of turbine blades integrated into a high-subsonic cascade test facility, which was designed for unsteady boundary layer investigations. The analysis of the experiment's results and comparison with the model's prediction confirm the validity of the model and its ability to predict accurately the unsteady boundary layer transition.

scholarly journals Boundary-Layer Transition Regions on Turbine Blade Suction Surfaces

1984 ◽  
Author(s):  
G. Roberts ◽  
A. Brown
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Boundary Layer Transition ◽  
Transition Model ◽  
Computer Programme ◽  
Layer Transition

This paper describes the results of an experimental investigation into extended boundary-layer transition regions on suction surfaces of four sets of turbine blades in a cascade rig. A transition model is proposed which is tested with some success in a modified version of STAN5, a boundary-layer computer programme.

NUMERICAL SIMULATION OF BOUNDARY LAYER TRANSITION FOR TURBINE BLADE HEAT TRANSFER PREDICTION

2017 ◽  
Vol 48 (10) ◽  
pp. 877-891
Author(s):  
Athmane Harizi ◽  
A. Gahmousse ◽  
E.-A. Mahfoudi ◽  
A. Mameri
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Boundary Layer ◽  
Turbine Blade ◽  
Boundary Layer Transition ◽  
Layer Transition

scholarly journals Periodic Unsteady Flow Aerodynamics and Heat Transfer: Studies on a Curved Surface, Combined Part I and II

2000 ◽  
Vol 6 (6) ◽  
pp. 393-416 ◽  
Author(s):  
M. T. Schobeiri ◽  
L. Wright ◽  
P. Chakka
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Convex Surface ◽  
Separation Bubble ◽  
Local Heat Transfer ◽  
Boundary Layer Transition ◽  
Wake Flow ◽  
Concave Surface ◽  
Layer Transition ◽  
Wake Passing

Aerodynamic and heat transfer investigations were done on a constant curvature curved plate in a subsonic wind tunnel facility for various wake passing frequencies and zero pressure gradient conditions. Steady and unsteady boundary layer transition measurements were taken on the concave surface of the curved plate at different wake passing frequencies where a rotating squirrel-cage generated the unsteady wake flow. The data were analyzed using timeaveraged and ensemble-averaged techniques to provide insight into the growth of the boundary layer and transition. Ensemble-averaged turbulence intensity contours in the temporal spatial domain showed that transition was induced for increasing wake passing frequency and structure. The local heat transfer coefficient distribution for the concave and convex surface was determined at those wake passing frequencies using a liquid crystal heat transfer measurement technique. Detailed aerodynamic and heat transfer investigations showed that higher wake passing frequency caused transition to occur earlier on the concave surface. Local Stanton numbers were also calculated on the concave surface and compared with Stanton numbers predicted using a differential boundary layer and heat transfer calculation method. On the convex side, no effect of wake passing frequency on heat transfer was observed due to a separation bubble that induced transition.

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