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.

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.

Effect of an Oscillating Flow Direction on Leading Edge Heat Transfer

1984 ◽  
Vol 106 (1) ◽  
pp. 222-228 ◽  
Author(s):  
M. L. Marziale ◽  
R. E. Mayle
Keyword(s):  
Heat Transfer ◽  
Strouhal Number ◽  
Large Scale ◽  
Flow Direction ◽  
Leading Edge ◽  
Periodic Variation ◽  
Scale Model ◽  
Transfer Rates ◽  
Large Scale Model ◽  
Turbulence Length

An experimental investigation was conducted to examine the effect of a periodic variation in the angle of attack on heat transfer at the leading edge of a gas turbine blade. A circular cylinder was used as a large-scale model of the leading edge region. The cylinder was placed in a wind tunnel and was oscillated rotationally about its axis. The incident flow Reynolds number and the Strouhal number of oscillation were chosen to model an actual turbine condition. Incident turbulence levels up to 4.9 percent were produced by grids placed upstream of the cylinder. The transfer rate was measured using a mass transfer technique and heat transfer rates inferred from the results. A direct comparison of the unsteady and steady results indicate that the effect is dependent on the Strouhal number, turbulence level, and the turbulence length scale, but that the largest observed effect was only a 10 percent augmentation at the nominal stagnation position.

Experimental Evaluations of the Relative Contributions to Overall Effectiveness in Turbine Blade Leading Edge Cooling

2018 ◽  
Author(s):  
Carol E. Bryant ◽  
Connor J. Wiese ◽  
James L. Rutledge ◽  
Marc D. Polanka
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Leading Edge ◽  
Internal Surface ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Impingement Cooling ◽  
External Cooling ◽  
Turbine Component ◽  
Overall Effectiveness

Gas turbine hot gas path components are protected through a combination of internal cooling and external film cooling. The coolant typically travels through internal passageways, which may involve impingement on the internal surface of a turbine component, before being ejected as film cooling. Internal cooling effects have been studied in facilities that allow measurement of heat transfer coefficients within models of the internal cooling paths, with large heat transfer coefficients generally desirable. External film cooling is typically evaluated through measurements of the adiabatic effectiveness and its effect on the external heat transfer coefficient. Efforts aimed at improving cooling are often focused on either only the internal cooling or the film cooling; however, the common coolant flow means the internal and external cooling schemes are linked and the coolant holes themselves provide another convective path for heat transfer to the coolant. Recently, measurements of overall cooling effectiveness using matched Biot number turbine component models allow evaluation of the nondimensional wall temperature achieved for the fully cooled component. However, the relative contributions of internal cooling, external cooling, and convection within the film cooling holes is not well understood. Large scale, matched Biot number experiments, complemented by CFD simulations, were performed on a fully film cooled cylindrical leading edge model to evaluate the effects of various alterations in the cooling design on the overall effectiveness. The relative influence of film cooling and cooling within the holes was evaluated by selectively disabling individual holes and quantifying how the overall effectiveness changed. Several internal impingement cooling schemes in addition to a baseline case without impingement cooling were also tested. In general, impingement cooling is shown to have a negligible influence on the overall effectiveness in the showerhead region. This indicates that the cost and pressure drop penalties for implementing impingement cooling may not be compensated by an increase in thermal performance. Instead, the internal cooling provided by convection within the holes themselves was shown, along with external film cooling, to be a dominant contribution to the overall cooling effectiveness. Indeed, the numerous holes within the showerhead region impede the ability of internal surface cooling schemes to influence the outside surface temperature. The results of this research may allow improved focus of future efforts on the forms of cooling with the greatest potential to improve cooling performance.

Heat Transfer Measurements in a Leading Edge Geometry With Racetrack Holes and Film Cooling Extraction

2012 ◽  
Author(s):  
Luca Andrei ◽  
Carlo Carcasci ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Francesco Maiuolo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Film Cooling ◽  
Large Scale ◽  
Internal Heat ◽  
Leading Edge ◽  
Jet Impingement ◽  
Internal Surface ◽  
Test Facility ◽  
Supply Channel

An experimental survey on a state of the art leading edge cooling scheme was performed to evaluate heat transfer coefficients (HTC) on a large scale test facility simulating an high pressure turbine airfoil leading edge cavity. Test section includes a trapezoidal supply channel with three large racetrack impingement holes. On the internal surface of the leading edge, four big fins are placed in order to confine impingement jets. The coolant flow impacts the leading edge internal surface and it is extracted from the leading edge cavity through 24 showerhead holes and 24 film cooling holes. The aim of the present study is to investigate the combined effects of jet impingement and mass flow extraction on the internal heat transfer of the leading edge. A non uniform mass flow extraction was also imposed to reproduce the effects of pressure side and suction side external pressure. Measurements were performed by means of a transient technique using narrow band Thermo-chromic Liquid Crystals (TLC). Jet Reynolds number and crossflow conditions into the supply channel were varied in order to cover the typical engine conditions of these cooling systems (Rej = 10000–40000). Experiments were compared with a numerical analysis on the same test case in order to better understand flow interaction inside the cavity. Results are reported in terms of detailed 2D maps, radial-wise and span-wise averaged values of Nusselt number.

Heat Transfer Measurements in a Leading Edge Geometry With Racetrack Holes and Film Cooling Extraction

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Luca Andrei ◽  
Carlo Carcasci ◽  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Francesco Maiuolo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mass Flow ◽  
Film Cooling ◽  
Large Scale ◽  
Internal Heat ◽  
Leading Edge ◽  
Jet Impingement ◽  
Internal Surface ◽  
Test Facility ◽  
Supply Channel

An experimental survey on a state of the art leading edge cooling scheme was performed to evaluate heat transfer coefficients (HTC) on a large scale test facility simulating a high pressure turbine airfoil leading edge cavity. The test section includes a trapezoidal supply channel with three large racetrack impingement holes. On the internal surface of the leading edge, four big fins are placed in order to confine impingement jets. The coolant flow impacts the leading edge internal surface, and it is extracted from the leading edge cavity through 24 showerhead holes and 24 film cooling holes. The aim of the present study is to investigate the combined effects of jet impingement and mass flow extraction on the internal heat transfer of the leading edge. A nonuniform mass flow extraction was also imposed to reproduce the effects of the pressure side and suction side external pressure. Measurements were performed by means of a transient technique using narrow band thermochromic liquid crystals (TLCs). Jet Reynolds number and crossflow conditions into the supply channel were varied in order to cover the typical engine conditions of these cooling systems (Rej=10,000-40,000). Experiments were compared with a numerical analysis on the same test case in order to better understand flow interaction inside the cavity. Results are reported in terms of detailed 2D maps, radial-wise, and span-wise averaged values of Nusselt number.

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.

Heat Transfer Studies on the Interior Surfaces of Cooled Nozzle Guide Vane in a Linear Cascade

2015 ◽  
Author(s):  
Arun Kumar Pujari ◽  
Bhamidi Prasad ◽  
Nekkanti Sitaram
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Guide Vane ◽  
Internal Heat ◽  
Leading Edge ◽  
Internal Surface ◽  
Transfer Coefficients ◽  
Computational Data ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Experimental and computational heat transfer investigations are reported in the interior side of a nozzle guide vane (NGV) subjected to combined impingement and film cooling. The domain of study is a two dimensional five-vane cascade having four passages. Each vane has a chord length of 228 mm and the pitch distance between the vanes is 200 mm. The vane internal surface is cooled by dry air supplied through the two impingement inserts: the front and the aft. The mass flow through the impingement chamber is varied, for a fixed spacing (H) to jet diameter (d) ratio of 1.2. The surface temperature distributions, at certain locations of the vane interior, are measured by pasting strips of liquid crystal sheets. The vane interior surface temperature distribution is also obtained by computations carried out by using Shear stress transport (SST) k-ω turbulence model in the ANSY FLUENT-14 flow solver. The computational data are in good agreement with the measured values of temperature. The internal heat transfer coefficients are thence determined along the leading edge and the mid span region from the computational data.

An Internal Heat Transfer Study in a Cooled Nozzle Guide Vane of a Linear Cascade

2014 ◽  
Author(s):  
Arun Kumar Pujari ◽  
Prasad B. V. S. S. Subrahmanyaa ◽  
Sitaram Nekkanti
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Film Cooling ◽  
Guide Vane ◽  
Internal Heat ◽  
Leading Edge ◽  
Internal Surface ◽  
Structure Variation ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Experimental and computational heat transfer investigations are reported in the interior mid span of the pressure surface of a Nozzle Guide Vane (NGV) subjected to combined impingement and film cooling. The study is carried out by considering a two dimensional cascade domain having four passages formed between the five vane each has a chord length of 228 mm and spacing (between the blades) of 200 mm. The vane internal surface is cooled by two impingement inserts namely front and aft impingement tubes. The front impingement tube is used to cool the internal side of the leading edge of the NGV whereas the aft impingement tube is used to cool mainly the mid span of the internal surface. The mass flow through the impingement chamber is varied for a fixed target plate distance to jet diameter ratio of 1.12. The surface temperature at the mid chord region was measured by liquid crystal technique. The surface temperature obtained from both experiments and computations are compared and the computationally obtained average heat transfer coefficient distribution along chord reported. The flow structure variation along the chord and its effect on Nusselt number distribution is presented. The computation is carried out by using Shear stress transport (SST) k-ω turbulence model in the ANSY FLUENT-14 flow solver.

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.

scholarly journals Experimental Determination of the Heat Transfer Coefficient of Real Cooled Geometry Using Linear Regression Method

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 180
Author(s):  
Asif Ali ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Linear Regression ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Surface ◽  
Regression Method ◽  
Thermal Transient

The scope of this work was to develop a technique based on the regression method and apply it on a real cooled geometry for measuring its internal heat transfer distribution. The proposed methodology is based upon an already available literature approach. For implementation of the methodology, the geometry is initially heated to a known steady temperature, followed by thermal transient, induced by injection of ambient air to its internal cooling system. During the thermal transient, external surface temperature of the geometry is recorded with the help of infrared camera. Then, a numerical procedure based upon a series of transient finite element analyses of the geometry is applied by using the obtained experimental data. The total test duration is divided into time steps, during which the heat flux on the internal surface is iteratively updated to target the measured external surface temperature. The final procured heat flux and internal surface temperature data of each time step is used to find the convective heat transfer coefficient via linear regression. This methodology is successfully implemented on three geometries: a circular duct, a blade with U-bend internal channel, and a cooled high pressure vane of real engine, with the help of a test rig developed at the University of Florence, Italy. The results are compared with the ones retrieved with similar approach available in the open literature, and the pros and cons of both methodologies are discussed in detail for each geometry.

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