Upstream Film Cooling on the Contoured Endwall of a Transonic Turbine Vane in an Annular Cascade

Abstract The isentropic exponent is one of the most important properties affecting gas dynamics. Nonetheless, its effect on turbine performance is not well known. This paper discusses a series of experimental and computational studies to determine the effect of isentropic exponent on the flow field within a turbine vane. Experiments are performed using a newly modified transient wind tunnel that enables annular cascade testing with a wide range of working fluids and operating conditions. For the present study, tests are undertaken using air, CO2, R134a, and argon, giving a range of isentropic exponent from 1.08 to 1.67. Measurements include detailed wall static pressures that are compared with computational simulations. Our results show that over the range of isentropic exponents tested here, the loss can vary between 20% and 35%, depending on vane exit Mach number. The results are important for future turbines operating with real-gas effects and/or those where high gas temperatures can lead to variations in the isentropic exponent.

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Determining Total Pressure Fields From Velocimetry Measurements in a Transonic Turbine Flowfield

10.1115/gt2021-59388 ◽

2021 ◽

Author(s):

Alexander Rusted ◽

Stephen Lynch

Keyword(s):

Film Cooling ◽

Compressible Flows ◽

Guide Vane ◽

Momentum Equation ◽

Inlet Guide Vane ◽

Pressure Fields ◽

Image Velocimetry ◽

Turbine Vane ◽

Total Temperature ◽

Transonic Turbine

Abstract This work describes a method for calculating pressure fields from temperature and velocity data in non-adiabatic compressible flows, such as the flow around a cooled turbine vane. Prior studies have demonstrated the ability to use particle image velocimetry methods to estimate the pressure gradient in the momentum equation, which is subsequently integrated to produce pressure fields. Due to changes in total temperature for non-adiabatic compressible flows, pressure fields cannot be computed from velocity measurements alone and temperature data must also be provided. In this work, a benchmarked steady 3D RANS simulation is used to generate velocity, temperature, and pressure fields in the transonic flow around a high-pressure turbine inlet guide vane. A procedure for solving the momentum equation and integrating for pressure is developed for non-adiabatic flows. Error is assessed by comparing calculated pressure to CFD predicted pressure, and the effects of PIV spatial resolution and measurement error are considered. The accuracy of the method on non-adiabatic flows is assessed using a vane with extensive film cooling. A clear benefit of incorporating temperature measurements in the pressure determination method is demonstrated, offering opportunities for deeper understanding of aerodynamic losses and entropy generation in cooled turbine flowfields.

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The Effect of Isentropic Exponent on Transonic Turbine Performance

Volume 2C: Turbomachinery ◽

10.1115/gt2019-90251 ◽

2019 ◽

Author(s):

David Baumgärtner ◽

John J. Otter ◽

Andrew P. S. Wheeler

Keyword(s):

Operating Conditions ◽

Turbine Performance ◽

Wide Range ◽

Turbine Vane ◽

Isentropic Exponent ◽

Real Gas Effects ◽

Transonic Turbine ◽

Exit Mach Number ◽

Transient Wind ◽

Annular Cascade

Abstract The isentropic exponent is one of the most important properties affecting gas dynamics. Nonetheless, its effect on turbine performance is not well known. The paper discusses a series of experimental and computational studies to determine the effect of isentropic exponent on the flow field within a turbine vane. Experiments are performed using a newly modified transient wind tunnel which enables annular cascade testing with a wide range of working fluids and operating conditions. For the present study tests are undertaken using air, CO2, R134a and argon, giving a range of isentropic exponent from 1.08–1.67. Measurements include detailed wall static pressures which are compared with computational simulations. Our results show that over the range of isentropic exponents tested here, the loss can vary by between 20%–35%, depending on vane exit Mach number. The results are important for future turbines operating with real-gas effects and/or those where high gas temperatures can lead to variations in isentropic exponent.

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Transonic Turbine-Vane Film Cooling with Showerhead Effect Using Pressure-Sensitive Paint Measurement Technique

Journal of Thermophysics and Heat Transfer ◽

10.2514/1.t5230 ◽

2018 ◽

Vol 32 (3) ◽

pp. 637-647 ◽

Cited By ~ 2

Author(s):

Chao-Cheng Shiau ◽

Nafiz H. K. Chowdhury ◽

Je-Chin Han ◽

Alexander V. Mirzamoghadam ◽

Ardeshir Riahi

Keyword(s):

Measurement Technique ◽

Film Cooling ◽

Pressure Sensitive Paint ◽

Pressure Sensitive ◽

Turbine Vane ◽

Transonic Turbine

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Effects of Leading Edge Film-Cooling and Surface Roughness on the Downstream Film-Cooling Along a Transonic Turbine Blade for Low and High Free-Stream Turbulence

10.21236/ada479415 ◽

2008 ◽

Author(s):

Sam Raben ◽

Pavlos Vlachos ◽

Wing Ng

Keyword(s):

Surface Roughness ◽

Turbine Blade ◽

Film Cooling ◽

Free Stream ◽

Leading Edge ◽

Free Stream Turbulence ◽

Transonic Turbine

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Aerodynamic Characterization of Transonic Turbine Vanes Optimized to Attenuate Rotor Forcing

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2011-46553 ◽

2011 ◽

Author(s):

R. Puente ◽

G. Paniagua ◽

T. Verstraete

Keyword(s):

High Efficiency ◽

Prediction Method ◽

Optimization Procedure ◽

3D Design ◽

Turbine Vanes ◽

Turbine Vane ◽

Loss Prediction ◽

Transonic Turbine ◽

Characteristic Features

A multi-objective optimization procedure is applied to the 3D design of a transonic turbine vane row, considering efficiency and stator outlet pressure distortion, which is directly related to induced rotor forcing. The characteristic features that define different individuals along the Pareto Front are described, analyzing the differences between high efficiency airfoils and low interaction. Pressure distortion is assessed by means of a model that requires only of the computation the steady flow field in the domain of the stator. The reduction of aerodynamic rotor forcing is checked via unsteady multistage aerodynamic computations. A well known loss prediction method is used to drive the efficiency of one optimization run, while CFD analysis is used for another, in order to assess the reliability of both methods. In both cases, the decomposition of total losses is performed to quantify the influence on efficiency of reducing rotor forcing. Results show that when striving for efficiency, the rotor is affected by few, but intense shocks. On the other hand, when the objective is the minimization of distortion, multiple shocks will appear.

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Evaluation of CFD simulations of film cooling performance on a turbine vane including conjugate heat transfer effects

International Journal of Heat and Fluid Flow ◽

10.1016/j.ijheatfluidflow.2014.08.010 ◽

2014 ◽

Vol 50 ◽

pp. 279-286 ◽

Cited By ~ 10

Author(s):

Thomas E. Dyson ◽

David G. Bogard ◽

Sean D. Bradshaw

Keyword(s):

Heat Transfer ◽

Film Cooling ◽

Conjugate Heat Transfer ◽

Transfer Effects ◽

Cfd Simulations ◽

Cooling Performance ◽

Turbine Vane ◽

Heat Transfer Effects

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Upstream Film Cooling on the Contoured Endwall of a Transonic Turbine Vane in an Annular Cascade

Volume 7B: Heat Transfer ◽

10.1115/gt2020-16188 ◽

2020 ◽

Author(s):

Daniel A. Salinas ◽

Izhar Ullah ◽

Lesley M. Wright ◽

Je-Chin Han ◽

John W. McClintic ◽

...

Keyword(s):

Film Cooling ◽

Density Ratio ◽

Lateral Spread ◽

Pressure Sensitive Paint ◽

Blow Down ◽

Film Cooling Effectiveness ◽

Pressure Sensitive ◽

Mainstream Flow ◽

Additional Protection ◽

Annular Cascade

Abstract The effects of mainstream flow velocity, density ratio (DR), and coolant-to-mainstream mass flow ratio (MFR) were investigated on a vane endwall in a transonic, annular cascade. A blow down facility consisting of five vanes was used. The film cooling effectiveness was measured using binary pressure sensitive paint (BPSP). The mainstream flow was set using isentropic exit Mach numbers of 0.7 and 0.9. The coolant-to-mainstream density ratio varied from 1.0 to 2.0. The coolant to mainstream MFR varied from 0.75% to 1.25%. The endwall was cooled by eighteen discrete holes located upstream of the vane passage to provide cooling to the upstream half of the endwall. Due to the curvature of the vane endwall, the upstream holes provided uniform coverage entering the endwall passage. The coverage was effective leading to the throat of the passage, where the downstream holes could provide additional protection. Increasing the coolant flowrate increased the effectiveness provided by the film cooling holes. Increasing the density of the coolant increases the effectiveness on the endwall while enhancing the lateral spread of the coolant. Finally, increasing the velocity of the mainstream while holding the MFR constant also yields increased protection on the endwall. Over the range of flow conditions considered in this study, the binary pressure sensitive paint proved to be a valuable tool for obtaining detailed pressure and film effectiveness distributions.

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Numerical Investigation of the Cooling Performance on the Endwall With and Without Fillet

Volume 5A: Heat Transfer ◽

10.1115/gt2018-76316 ◽

2018 ◽

Author(s):

Qingzong Xu ◽

Qiang Du ◽

Pei Wang ◽

Jun Liu ◽

Guang Liu

Keyword(s):

Secondary Flow ◽

Turbulence Model ◽

Film Cooling ◽

Computational Method ◽

Inlet Temperature ◽

Cooling Effectiveness ◽

Cooling Performance ◽

Film Cooling Effectiveness ◽

Numerical Predictions ◽

Turbine Vane

High inlet temperature of turbine vane increases the demand of high film cooling effectiveness. Vane endwall region was extensively cooled due to the high and flat exit temperature distribution of combustor. Leakage flow from the combustor-turbine gap was used to cool the endwall region except for preventing hot gas ingestion. Numerical predictions were conducted to investigate the flow structure and adiabatic film cooling effectiveness of endwall region in a linear cascade with vane-endwall junction fillet. The simulations were completed by solving the three-dimensional Reynolds-Averaged Navier-Stokes(RANS) equations with shear stress transport(SST) k-ω turbulence model, meanwhile, the computational method and turbulence model were validated by comparing computational result with the experiment. Three types of linear fillet with the length-to-height ratio of 0.5, 1 and 2, named fillet A, fillet B and fillet C respectively, were studied. In addition, circular fillet with radius of 2mm was compared with linear fillet B. The interrupted slot, produced by changing the way of junction of combustor and turbine vane endwall, is introduced at X/Cax = −0.2 upstream of the vane leading edge. Results showed that fillet can significantly affect the cooling performance on the endwall due to suppressing the strength of the secondary flow. Fillet C presented the best cooling performance comparing to fillet A and fillet B because a portion of the coolant which climbs to the fillet was barely affected by secondary flow. Results also showed the effect of fillet on the total pressure loss. The result indicated that only fillet A slightly decreases endwall loss.

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