Author: Joshua Brian Anderson
Publisher:
ISBN:
Category :
Languages : en
Pages : 572
Book Description
Film cooling is widely used in gas turbine engines to manage temperatures within the hot section of the engine. In this work, several investigations are described, all of which studied how fundamental hydrodynamic and thermal parameters influence the performance of film cooling. The first investigation studied the impact of freestream turbulence, boundary layer thickness, Reynolds number, and Mach number on film cooling performance, using axial shaped film cooling holes. The second study considered a similar set of parameters, and investigated their impact on compound-angle oriented film cooling holes. Both of these studies utilized measurements of adiabatic effectiveness and heat transfer coefficient augmentation. In general, the parameters had effects which were dependent on the coolant flow rate and density ratio. The final study considered methods to reduce the experimental uncertainty which arises from conduction and radiation errors in thermal measurements. A careful evaluation of the thermal boundary layer was used to validate these corrections
Investigation of Approach Flow Parameters, Scaling Factors, and Measurement Accuracy for Film Cooling Effectiveness and Heat Transfer Coefficient Measurements
Author: Joshua Brian Anderson
Publisher:
ISBN:
Category :
Languages : en
Pages : 572
Book Description
Film cooling is widely used in gas turbine engines to manage temperatures within the hot section of the engine. In this work, several investigations are described, all of which studied how fundamental hydrodynamic and thermal parameters influence the performance of film cooling. The first investigation studied the impact of freestream turbulence, boundary layer thickness, Reynolds number, and Mach number on film cooling performance, using axial shaped film cooling holes. The second study considered a similar set of parameters, and investigated their impact on compound-angle oriented film cooling holes. Both of these studies utilized measurements of adiabatic effectiveness and heat transfer coefficient augmentation. In general, the parameters had effects which were dependent on the coolant flow rate and density ratio. The final study considered methods to reduce the experimental uncertainty which arises from conduction and radiation errors in thermal measurements. A careful evaluation of the thermal boundary layer was used to validate these corrections
Publisher:
ISBN:
Category :
Languages : en
Pages : 572
Book Description
Film cooling is widely used in gas turbine engines to manage temperatures within the hot section of the engine. In this work, several investigations are described, all of which studied how fundamental hydrodynamic and thermal parameters influence the performance of film cooling. The first investigation studied the impact of freestream turbulence, boundary layer thickness, Reynolds number, and Mach number on film cooling performance, using axial shaped film cooling holes. The second study considered a similar set of parameters, and investigated their impact on compound-angle oriented film cooling holes. Both of these studies utilized measurements of adiabatic effectiveness and heat transfer coefficient augmentation. In general, the parameters had effects which were dependent on the coolant flow rate and density ratio. The final study considered methods to reduce the experimental uncertainty which arises from conduction and radiation errors in thermal measurements. A careful evaluation of the thermal boundary layer was used to validate these corrections
Applied Mechanics Reviews
Surface Measurements and Predictions of Full-coverage Film Cooling
Author: Greg Natsui
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
Full-coverage film cooling is investigated both experimentally and numerically. First, surface measurements local of adiabatic film cooling eeffectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-[epsilon] and SST k-[omega], and their ability to predict local film cooling effectiveness throughout a full-coverage array. The objective of the experimental study is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of two different hole-to-hole spacings (P/D = X/D = 14.5; 19.8) and two different hole inclination angles ([alpha] = 30°; 45°), with cylindrical holes compounded relative to the flow ([beta] = 45°) and arranged in a staggered configuration. Arrays of up to 30 rows are tested so that the superposition effect of the coolant film can be studied. In addition, shortened arrays of up to 20 rows of coolant holes are also tested so that the decay of the coolant film following injection can be studied. Levels of laterally averaged effectiveness reach values as high as [eta with line above]= 0.5, and are not yet at the asymptotic limit even after 20-30 rows of injection for all cases studied. Levels of heat transfer augmentation asymptotically approach values of h=h0 [almost equal to] 1.35 rather quickly, only after 10 rows. It is conjectured that the heat transfer augmentation levels off very quickly due to the boundary layer reaching an equilibrium in which the perturbation from additional film rows has reached a balance with the damping effect resulting from viscosity. The levels of laterally averaged adiabatic film cooling effectiveness far exceeding [eta with line above]= 0.5 are much higher than expected. The heat transfer augmentation levels off quickly as opposed to the film effectiveness which continues to rise (although asymptotically) at large row numbers. This ensures that an increased row count represents coolant well spent. The numerical predictions are carried out in order to test the ability of the two most common turbulence models to properly predict full-coverage film cooling. The two models chosen, Realizable k-[epsilon] (RKE) and Shear Stress Transport k-[omega] (SSTKW), are both two-equation models coupled with Reynolds Averaged governing equations which make several gross physical assumptions and require several empirical values. Hence, the models are not expected to provide perfect results. However, very good average values are seen tobe obtained through these simple models. Using RKE in order to model full-coverage filmcooling will yield results with 30% less error than selecting SSTKW.
Publisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
Full-coverage film cooling is investigated both experimentally and numerically. First, surface measurements local of adiabatic film cooling eeffectiveness and heat transfer augmentation for four different arrays are described. Reported next is a comparison between two very common turbulence models, Realizable k-[epsilon] and SST k-[omega], and their ability to predict local film cooling effectiveness throughout a full-coverage array. The objective of the experimental study is the quantification of local heat transfer augmentation and adiabatic film cooling effectiveness for four surfaces cooled by large, both in hole count and in non-dimensional spacing, arrays of film cooling holes. The four arrays are of two different hole-to-hole spacings (P/D = X/D = 14.5; 19.8) and two different hole inclination angles ([alpha] = 30°; 45°), with cylindrical holes compounded relative to the flow ([beta] = 45°) and arranged in a staggered configuration. Arrays of up to 30 rows are tested so that the superposition effect of the coolant film can be studied. In addition, shortened arrays of up to 20 rows of coolant holes are also tested so that the decay of the coolant film following injection can be studied. Levels of laterally averaged effectiveness reach values as high as [eta with line above]= 0.5, and are not yet at the asymptotic limit even after 20-30 rows of injection for all cases studied. Levels of heat transfer augmentation asymptotically approach values of h=h0 [almost equal to] 1.35 rather quickly, only after 10 rows. It is conjectured that the heat transfer augmentation levels off very quickly due to the boundary layer reaching an equilibrium in which the perturbation from additional film rows has reached a balance with the damping effect resulting from viscosity. The levels of laterally averaged adiabatic film cooling effectiveness far exceeding [eta with line above]= 0.5 are much higher than expected. The heat transfer augmentation levels off quickly as opposed to the film effectiveness which continues to rise (although asymptotically) at large row numbers. This ensures that an increased row count represents coolant well spent. The numerical predictions are carried out in order to test the ability of the two most common turbulence models to properly predict full-coverage film cooling. The two models chosen, Realizable k-[epsilon] (RKE) and Shear Stress Transport k-[omega] (SSTKW), are both two-equation models coupled with Reynolds Averaged governing equations which make several gross physical assumptions and require several empirical values. Hence, the models are not expected to provide perfect results. However, very good average values are seen tobe obtained through these simple models. Using RKE in order to model full-coverage filmcooling will yield results with 30% less error than selecting SSTKW.
International Aerospace Abstracts
Effects of Hole Length, Supply Plenum Geometry, and Freestream Turbulence on Film Cooling Performance
NASA SP.
ASME Technical Papers
Author:
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 472
Book Description
Publisher:
ISBN:
Category : Mechanical engineering
Languages : en
Pages : 472
Book Description