Experimental Measurements and Computational Predictions for an Internally Cooled Simulated Turbine Vane With 90 Degree Rib Turbulators

2010 ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
External Surface ◽  
Internal Heat ◽  
Experimental Measurements ◽  
Surface Temperatures ◽  
Turbine Vane ◽  
Internally Cooled ◽  
Rib Turbulators ◽  
Overall Effectiveness ◽  
Computational Predictions

An experimental and computational conjugate heat transfer study of an internally cooled, scaled-up simulated turbine vane with internal rib turbulators was performed. The conjugate nature of the model allowed for the effects of the internal ribs to be seen on the external overall effectiveness distribution. The enhanced internal heat transfer coefficient caused by the ribs increased the cooling capacity of the internal cooling circuit, lowering the overall metal temperature. External surface temperatures, internal surface temperatures, and coolant inlet and exit temperatures were measured and compared to data obtained from a non-ribbed model over a range of internal coolant Reynolds numbers. Internal rib turbulators were found to increase the overall effectiveness on the vane external surface by up to 50% relative to the non-ribbed model. Additionally, comparisons between the experimental measurements and computational predictions are presented.

Experimental Measurements and Computational Predictions for an Internally Cooled Simulated Turbine Vane With 90 Degree Rib Turbulators

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
External Surface ◽  
Internal Heat ◽  
Experimental Measurements ◽  
Surface Temperatures ◽  
Turbine Vane ◽  
Internally Cooled ◽  
Rib Turbulators ◽  
Overall Effectiveness ◽  
Computational Predictions

An experimental and computational conjugate heat transfer study of an internally cooled, scaled-up simulated turbine vane with internal rib turbulators was performed. The conjugate nature of the model allowed for the effects of the internal ribs to be seen on the external overall effectiveness distribution. The enhanced internal heat transfer coefficient caused by the ribs increased the cooling capacity of the internal cooling circuit, lowering the overall metal temperature. External surface temperatures, internal surface temperatures, and coolant inlet and exit temperatures were measured and compared to data obtained from a non-ribbed model over a range of internal coolant Reynolds numbers. Internal rib turbulators were found to increase the overall effectiveness on the vane external surface by up to 50% relative to the non-ribbed model. Additionally, comparisons between the experimental measurements and computational predictions are presented.

Momentum and Thermal Boundary Layer Development on an Internally Cooled Turbine Vane

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Conjugate Heat Transfer ◽  
Freestream Turbulence ◽  
Boundary Layer Development ◽  
Turbine Vane ◽  
Internally Cooled ◽  
Momentum Boundary Layer ◽  
Computational Predictions

Recent advances in computing power have made conjugate heat transfer simulations of turbine components increasingly popular; however, limited experimental data exist with which to evaluate these simulations. The primary parameter used to evaluate simulations is often the external surface temperature distribution, or overall effectiveness. In this paper, the overlying momentum and thermal boundary layers at various streamwise positions around a conducting, internally cooled simulated turbine vane were measured under low (Tu = 0.5%) and high (Tu = 20%) freestream turbulence conditions. Furthermore, experimental results were compared to computational predictions. In regions where a favorable pressure gradient existed, the thermal boundary layer was found to be significantly thicker than the accompanying momentum boundary layer. Elevated freestream turbulence had the effect of thickening the thermal boundary layer much more effectively than the momentum boundary layer over the entire vane. These data are valuable in understanding the conjugate heat transfer effects on the vane as well as serving as a tool for computational code evaluation.

Adiabatic and Overall Effectiveness for the Showerhead Film Cooling of a Turbine Vane

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Marc L. Nathan ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Internal Heat ◽  
Flux Ratio ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Turbine Vane ◽  
Dynamics Simulations ◽  
Overall Effectiveness

There have been a number of previous studies of the adiabatic film effectiveness for the showerhead region of a turbine vane, but no previous studies of the overall cooling effectiveness. The overall cooling effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components, and the internal cooling is designed so that the ratio of the external to internal heat transfer coefficient is matched to that of the engine. In this study, the overall effectiveness was experimentally measured on a model turbine vane constructed of a material to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. The cooling design consisted of a showerhead composed of five rows of holes with one additional row on both pressure and suction sides of the vane. An identical model was also constructed out of low conductivity foam to measure adiabatic film effectiveness. Of particular interest in this study was to use the overall cooling effectiveness measurements to identify local hot spots which might lead to failure of the vane. Furthermore, the experimental measurements provided an important database for evaluation of computational fluid dynamics simulations of the conjugate heat transfer effects that occur in the showerhead region. Continuous improvement in both measures of performance was demonstrated with increasing momentum flux ratio.

Experimental Measurements and Computational Predictions for an Internally Cooled Simulated Turbine Vane

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Large Scale ◽  
Leading Edge ◽  
Internal Surface ◽  
Scale Model ◽  
Experimental Measurements ◽  
Internal Cooling ◽  
Internally Cooled ◽  
Computational Predictions

In this study the conjugate heat transfer effects for an internally cooled vane were studied experimentally and computationally. Experimentally, a large scale model vane was used with an internal cooling configuration characteristic of real gas turbine airfoils. The cooling configuration employed consisted of a U-bend channel for cooling the leading edge region of the airfoil and a radial channel for cooling the middle third of the vane. The thermal conductivity of the solid was specially selected so that the Biot number for the model matched typical engine conditions. This ensured that scaled nondimensional surface temperatures for the model were representative of those in the first stage of a high pressure turbine. The performance of the internal cooling circuit was quantified experimentally for internal flow Reynolds numbers ranging from 10,000 to 40,000. The external surface temperature distribution was mapped over the entire vane surface. Additional measurements, including internal surface temperature measurements as well as coolant inlet and exit temperatures, were conducted. Comparisons between the experimental measurements and computational predictions of external heat transfer coefficient are presented.

Momentum and Thermal Boundary Layer Development on an Internally Cooled Turbine Vane

2010 ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Conjugate Heat Transfer ◽  
Freestream Turbulence ◽  
Boundary Layer Development ◽  
Turbine Vane ◽  
Internally Cooled ◽  
Momentum Boundary Layer ◽  
Computational Predictions

Recent advances in computing power have made conjugate heat transfer simulations of turbine components increasingly popular; however, limited experimental data exists with which to evaluate these simulations. The primary parameter used to evaluate simulations is often the external surface temperature distribution, or overall effectiveness. In this paper, the overlying momentum and thermal boundary layers at various streamwise positions around a conducting, internally cooled simulated turbine vane were measured under low (Tu = 0.5%) and high (Tu = 20%) freestream turbulence conditions. Furthermore, experimental results were compared to computational predictions. In regions were a favorable pressure gradient existed, the thermal boundary layer was found to be significantly thicker than the accompanying momentum boundary layer. Elevated freestream turbulence had the effect of thickening the thermal boundary layer much more effectively than the momentum boundary layer over the entire vane. This data is valuable in understanding the conjugate heat transfer effects on the vane as well as serving as a tool for computational code evaluation.

Experimental Measurements and Computational Predictions for an Internally Cooled Simulated Turbine Vane

2009 ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Large Scale ◽  
Leading Edge ◽  
Internal Surface ◽  
Scale Model ◽  
Experimental Measurements ◽  
Internal Cooling ◽  
Internally Cooled ◽  
Computational Predictions

In this study the conjugate heat transfer effects for an internally cooled vane were studied experimentally and computationally. Experimentally, a large scale model vane was used with an internal cooling configuration characteristic of real gas turbine airfoils. The cooling configuration employed consisted of a U-bend channel for cooling the leading edge region of the airfoil and a radial channel for cooling the middle third of the vane. The thermal conductivity of the solid was specially selected so that the Biot number for the model matched typical engine conditions. This ensured that scaled non-dimensional surface temperatures for the model were representative of those in the first stage of a HPT. The performance of the internal cooling circuit was quantified experimentally for internal flow Reynolds numbers ranging from 10,000 to 40,000. The external surface temperature distribution was mapped over the entire vane surface. Additional measurements, including internal surface temperature measurements as well as coolant inlet and exit temperatures were conducted. Comparisons between the experimental measurements and computational predictions of external heat transfer coefficient are presented.

Adiabatic and Overall Effectiveness for the Showerhead Film Cooling of a Turbine Vane

2012 ◽  
Author(s):  
Marc L. Nathan ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Internal Heat ◽  
Flux Ratio ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Turbine Vane ◽  
Engine Components ◽  
Overall Effectiveness

There have been a number of previous studies of the adiabatic film effectiveness for the showerhead region of a turbine vane, but no previous studies of the overall cooling effectiveness. The overall cooling effectiveness is a measure of the external surface temperature relative to the mainstream temperature and the inlet coolant temperature, and consequently is a direct measure of how effectively the surface is cooled. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components, and the internal cooling is designed so that the ratio of the external to internal heat transfer coefficient is matched to that of the engine. In this study, the overall effectiveness was experimentally measured on a model turbine vane constructed of a material to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. The cooling design consisted of a showerhead composed of five rows of holes with one additional row on both pressure and suction sides of the vane. An identical model was also constructed out of low conductivity foam to measure adiabatic film effectiveness. Of particular interest in this study was to use the overall cooling effectiveness measurements to identify local hot spots which might lead to failure of the vane. Furthermore, the experimental measurements provided an important database for evaluation of CFD simulations of the conjugate heat transfer effects that occur in the showerhead region. Continuous improvement in both measures of performance was demonstrated with increasing momentum flux ratio.

The Measurement of Full-Surface Internal Heat Transfer Coefficients for Turbine Airfoils Using a Non-Destructive Thermal Inertia Technique

2002 ◽  
Author(s):  
Nirm V. Nirmalan ◽  
Ronald S. Bunker ◽  
Carl R. Hedlung
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Turbine Airfoils ◽  
Non Destructive ◽  
Internal Heat Transfer

A new method has been developed and demonstrated for the non-destructive, quantitative assessment of internal heat transfer coefficient distributions of cooled metallic turbine airfoils. The technique employs the acquisition of full-surface external surface temperature data in response to a thermal transient induced by internal heating/cooling, in conjunction with knowledge of the part wall thickness and geometry, material properties, and internal fluid temperatures. An imaging Infrared camera system is used to record the complete time history of the external surface temperature response during a transient initiated by the introduction of a convecting fluid through the cooling circuit of the part. The transient data obtained is combined with the cooling fluid network model to provide the boundary conditions for a finite element model representing the complete part geometry. A simple 1D lumped thermal capacitance model for each local wall position is used to provide a first estimate of the internal surface heat transfer coefficient distribution. A 3D inverse transient conduction model of the part is then executed with updated internal heat transfer coefficients until convergence is reached with the experimentally measured external wall temperatures as a function of time. This new technique makes possible the accurate quantification of full-surface internal heat transfer coefficient distributions for prototype and production metallic airfoils in a totally non-destructive and non-intrusive manner. The technique is equally applicable to other material types and other cooled/heated components.

Evaluation of CFD Simulations of Film Cooling Performance in the Showerhead Region of a Turbine Vane Including Conjugate Effects

2012 ◽  
Author(s):  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Leading Edge ◽  
External Boundary ◽  
Experimental Measurements ◽  
Impingement Cooling ◽  
Heat Transfer Augmentation ◽  
Turbine Vane ◽  
Sst Turbulence Model ◽  
Investigate Heat Transfer

Computational simulations using RANS and the k-ω SST turbulence model were performed to complement experimental measurements of overall cooling effectiveness and adiabatic film effectiveness for a film cooled turbine vane airfoil. Particular attention was placed on the showerhead. The design made use of five rows of showerhead holes and a single gill row on both pressure and suction sides. The simulated geometry also included the internal impingement cooling configuration. Internal and external boundary conditions were matched to experiments using the same vane model. To correctly simulate conjugate heat transfer effects, the experimental vane model was constructed to match the Biot number for engine conditions. Computational predictions of the overall and adiabatic effectiveness were compared to experimental measurements from both the conducting vane and a model constructed from low conductivity foam. The results show that the k-ω SST RANS model over-predicts both adiabatic and overall effectiveness due in part to limited jet diffusion. The simulations were also used to investigate heat transfer augmentation, which is difficult to measure experimentally in the showerhead region. The results showed substantial augmentation of 1.5 or more over large portions of the leading edge, with many areas exceeding 2.0. However, the simulations also showed a reduction in heat transfer (i.e., hf/h0 < 1) for locations beneath the coolant jets. This result was likely due to Taw being an inappropriate driving temperature for separated jets.

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