Effects of Bulk Flow Pulsations on Film Cooling With Compound Angle Holes: Heat Transfer Coefficient Ratio and Heat Flux Ratio

2001 ◽  
Vol 124 (1) ◽  
pp. 142-151 ◽  
Author(s):  
In Sung Jung ◽  
Joon Sik Lee ◽  
P. M. Ligrani
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Surface Heat Transfer ◽  
Spatially Resolved ◽  
Compound Angle

Experiments are conducted to investigate the effects of bulk flow pulsations on film cooling from compound angle holes. A row of five film cooling holes is employed with orientation angles of 0, 30, 60, and 90 deg at a fixed inclination angle of 35 deg. Static pressure pulsations are generated using an array of six rotating shutter blades, which extend across the span of the exit of the wind tunnel test section. Pulsation frequencies of 0 Hz, 8 Hz, and 36 Hz, and time-averaged blowing ratios of 0.5, 1.0, and 2.0 are employed. Corresponding coolant Strouhal numbers based on these values then range from 0.20 to 3.6. Spatially resolved surface heat transfer coefficient distributions are measured (with the film and freestream at the same temperature) using thermochromic liquid crystals. Presented are ratios of surface heat transfer coefficients with and without film cooling, as well as ratios of surface heat flux with and without film cooling. These results, for compound angle injection, indicate that the pulsations cause the film to be spread more uniformly over the test surface than when no pulsations are employed. This is because the pulsations cause the film from compound angle holes to oscillate in both the normal and spanwise directions after it leaves the holes. As a result, the pulsations produce important changes to spatially resolved distributions of surface heat flux ratios, and surface heat transfer coefficient ratios. In spite of these alterations, only small changes to spatially averaged heat transfer coefficient ratios are produced by the pulsations. Spatially averaged surface heat flux ratios, on the other hand, increase considerably at coolant Strouhal numbers larger than unity, with higher rates of increase at larger orientation angles.

Effects of Bulk Flow Pulsations on Film Cooling With Compound Angle Holes: Heat Transfer Coefficient Ratio and Heat Flux Ratio

2001 ◽  
Author(s):  
In Sung Jung ◽  
Joon Sik Lee ◽  
P. M. Ligrani
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Surface Heat Flux ◽  
Surface Heat ◽  
Surface Heat Transfer ◽  
Spatially Resolved ◽  
Compound Angle

Experiments are conducted to investigate the effects of bulk flow pulsations on film cooling from compound angle holes. A row of five film cooling holes is employed with orientation angles of 0°, 30°, 60°, and 90° at a fixed inclination angle of 35°. Static pressure pulsations are generated using an array of six rotating shutter blades, which extend across the span of the exit of the wind tunnel test section. Pulsation frequencies of 0 Hz, 8 Hz, and 36 Hz, and time-averaged blowing ratios of 0.5, 1.0, and 2.0 are employed. Corresponding coolant Strouhal numbers based on these values then range from 0.20 to 3.6. Spatially-resolved surface heat transfer coefficient distributions are measured (with the film and freestream at the same temperature) using thermochromic liquid crystals. Presented are ratios of surface heat transfer coefficients with and without film cooling, as well as ratios of surface heat flux with and without film cooling. These results, for compound angle injection, indicate that the pulsations cause the film to be spread more uniformly over the test surface than when no pulsations are employed. This is because the pulsations cause the film from compound angle holes to oscillate in both the normal and spanwise directions after it leaves the holes. As a result, the pulsations produce important changes to spatially-resolved distributions of surface heat flux ratios, and surface heat transfer coefficient ratios. In spite of these alterations, only small changes to spatially-averaged heat transfer coefficient ratios are produced by the pulsations. Spatially-averaged surface heat flux ratios, on the other hand, increase considerably at coolant Strouhal numbers larger than unity, with higher rates of increase at larger orientation angles.

Heat Transfer Coefficient Augmentation for a Shaped Film Cooling Hole at a Range of Compound Angles

2020 ◽  
pp. 1-30
Author(s):  
Shane Haydt ◽  
Stephen Lynch
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Constant Heat Flux ◽  
Cooling Hole ◽  
Adiabatic Effectiveness ◽  
Compound Angle ◽  
The Heat Transfer Coefficient

Abstract Film cooling holes with shaped diffusers are used to efficiently deliver coolant to the surface of a gas turbine part to keep metal temperatures low. Reducing the heat flux into a component, relative to a case with no coolant injection, is the ultimate goal of film cooling. This reduction in heat flux is primarily achieved via a lower driving temperature at the wall for convection, represented by the adiabatic effectiveness. Another important consideration, however, is how the disturbance to the flowfield and thermal field caused by the injection of coolant augments the heat transfer coefficient. The present study examines the spatially-resolved heat transfer coefficient augmentation, measured using a constant heat flux foil and IR thermography, for a shaped film cooling hole at a range of compound angles. Results show that the heat transfer coefficient increases with compound angle and with blowing ratio. Due to the unique asymmetric flowfield of a compound angle hole, a significant amount of augmentation occurs to the side of the film cooling jet, where very little coolant is present. This causes local regions of increased heat flux, which is counter to the goal of film cooling. Heat transfer results are compared with adiabatic effectiveness and flowfield measurements from a previous study.

Surface Heat Transfer Coefficient’s Calculation of W9Mo3Cr4V during Cryogenic Treatment

2010 ◽  
Vol 43 ◽  
pp. 424-429
Author(s):  
Zi Ran Liu ◽  
Cai Xia Ren ◽  
Xian Guo Yan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flux Density ◽  
Heat Flux Density ◽  
Cryogenic Treatment ◽  
Surface Heat ◽  
Surface Heat Transfer ◽  
Surface Heat Transfer Coefficient

In the process of the finite element analogy of the Cryogenic Treatment of the high speed steel cutter with respect to the material of W9Mo3Cr4V, the surface heat transfer coefficient is a crucial parameter. In order to get this parameter, this paper employed the method of inverse heat conduction to process the temperature curve generated through the cryogenic treatment of the tested work piece with the material of W9Mo0Cr4V, thereby obtaining the surface heat transfer coefficient of the tested work piece. This coefficient can be considered the surface heat transfer coefficient of cryogenic treatment of the cutter with the same material. The principle of the inverse heat conduction is as follows: firstly, according to the boundary condition and the initial value in the tri-dimensional space, the equation of the sensitivity coefficient and the temperature field can be deduced. Second, the coupling of two equations is carried out, and the heat flux density is calculated based on above result. The heat flux density will be revise to get the reasonable value . Lastly, the surface heat transfer coefficient can be obtained by the heat flux density. In this paper, all the work is automatically accomplished with the aid of FEPG soft ware and Visual C++ programmable language.

Systematic Experimental and Numerical Investigations on the Aerothermodynamics of a Film Cooled Turbine Cascade With Variation of the Cooling Hole Shape: Part I — Experimental Approach

2000 ◽  
Author(s):  
Wolfgang Ganzert ◽  
Thomas Hildebrandt ◽  
Leonhard Fottner
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Suction Side ◽  
Surface Heat ◽  
Turbine Cascade ◽  
Lateral Expansion ◽  
Surface Heat Transfer ◽  
Hole Shape

As a part of a systematic research program isothermal investigations on the aerodynamics and the heat transfer of a large scale turbine cascade with suction side film cooling with shaped holes and compound inclination were carried out. The film cooling through a row of holes at forty percent chord length on the suction side was supplied by a large plenum chamber. The axial component inclination was kept constant at 30°. All holes have a cylindrical inlet combined with a shaped outlet. Three injection geometries were tested. The first two investigated configurations had no lateral inclination. The hole geometries can be briefly described as follows: Fan-shaped holes with lateral expansion, fan-shaped holes with lateral expansion and streamwise laid-back. The last investigation combined the most complex hole shape with a lateral hole inclination of 45°. Typical engine conditions for the Mach and Reynolds number as well as the inlet turbulence level were maintained. Due to hardware limitations the total temperature was set to 303 Kelvin. The measured data comprise local and integral total pressure loss coefficients obtained by pressure probe traversing at midspan downstream of the cascade. The static profile pressure distribution together with oil-and-dye flow visualisation gives information on the surface flow conditions and boundary layer development especially in the near hole region. Three dimensional hot wire anemometry is used for detailed flow measurements in the hole region. Based on the steady state liquid crystal heat transfer measurement technique pseudo colour contour plots are used for the documentation of the local surface heat transfer coefficient distribution. Laterally averaged and statistically analysed data of the surface heat transfer is applied in further heat transfer examinations. The aim of all investigations is an aerodynamical optimisation of film cooling configurations taking into account the thermal aspects. The most important conclusions can be summarised as follows: Compared to cylindrical holes with the same axial injection angle, shaped holes have a tremendous influence on the flow type in the near hole region. This leads to a more homogeneous pattern of the suction side heat transfer coefficient. The combination of shaped holes and lateral inclination induces definitely higher losses downstream of the cascade compared to the case with no inclination. Due to the lateral injection the former symmetrical vortex branches downstream of the hole are increased asymmetrically. This leads to higher mean heat transfer coefficients in the near hole region downstream of the injection. On the other side laterally blowing increases the homogeneity of the heat transfer coefficient.

Heat Transfer Coefficient Augmentation for a Shaped Film Cooling Hole at a Range of Compound Angles

2019 ◽  
Author(s):  
Shane Haydt ◽  
Stephen Lynch
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Constant Heat Flux ◽  
Cooling Hole ◽  
Adiabatic Effectiveness ◽  
Compound Angle ◽  
The Heat Transfer Coefficient

Abstract Shaped film cooling holes are used to efficiently deliver coolant to the surface of a gas turbine part to keep metal temperatures low. The ultimate goal of film cooling is to reduce the heat flux into a component, relative to a case with no coolant injection. This reduction in heat flux is primarily achieved via a lower driving temperature at the wall for convection, represented by the adiabatic effectiveness. Another important consideration, however, is how the disturbance to the flowfield and thermal field caused by the injection of coolant augments the heat transfer coefficient. The present study examines the spatially-resolved heat transfer coefficient augmentation for a shaped film cooling hole at a range of compound angles, using a constant heat flux foil and IR thermography. Results show that the heat transfer coefficient increases with compound angle and with blowing ratio. Due to the unique asymmetric flowfield of a compound angle hole, a significant amount of augmentation occurs to the side of the film cooling jet, where very little coolant is present. This causes local regions of increased heat flux, which is counter to the goal of film cooling. Heat transfer results are compared with adiabatic effectiveness and flowfield measurements from a previous study.

The Research on the Key Factor Affect the Precision in Stress Analysis for the Rotor of Steam Turbine

2013 ◽  
Vol 275-277 ◽  
pp. 83-86
Author(s):  
Chun Lin Zhang ◽  
Nian Su Hu ◽  
Wen Yang ◽  
Jian Mei Wang ◽  
Min Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Numerical Calculation ◽  
Transfer Coefficient ◽  
Stress Analysis ◽  
Surface Heat ◽  
Flow State ◽  
Surface Heat Transfer ◽  
Surface Heat Transfer Coefficient ◽  
Key Factor

With the development of the power grid, the proportion of large capacity unit is increasing rapidly. It requires a more in-depth study on the reliability of the unit, especially for the unit adjusting the peak. This paper concerned on the research of the surface heat transfer coefficient, which is the key factor affect the precision in thermal stress analysis. The surface heat transfer coefficient is obtained via the numerical calculation for the steam’s flow state and the transient heat transfer between rotor. This paper mainly describes the steam’s flow state and the transient heat transfer with the steam seal, and the results show that the direct numerical calculation is resultful in this subject.

Freestream Flow Effects on Film Effectiveness and Heat Transfer Coefficient Augmentation for Compound Angle Shaped Holes

2017 ◽  
Author(s):  
Joshua B. Anderson ◽  
John W. McClintic ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
Zachary Webster
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Layer Thickness ◽  
Film Cooling ◽  
Gas Turbines ◽  
Boundary Layer Thickness ◽  
Adiabatic Effectiveness ◽  
Compound Angle

The use of compound-angled shaped film cooling holes in gas turbines provides a method for cooling regions of extreme curvature on turbine blades or vanes. These configurations have received surprisingly little attention in the film cooling literature. In this study, a row of laid-back fanshaped holes based on an open-literature design, were oriented at a 45-degree compound angle to the approaching freestream flow. In this study, the influence of the approach flow boundary layer thickness and character were experimentally investigated. A trip wire and turbulence generator were used to vary the boundary layer thickness and freestream conditions from a thin laminar boundary layer flow to a fully turbulent boundary layer and freestream at the hole breakout location. Steady-state adiabatic effectiveness and heat transfer coefficient augmentation were measured using high-resolution IR thermography, which allowed the use of an elevated density ratio of DR = 1.20. The results show adiabatic effectiveness was generally lower than for axially-oriented holes of the same geometry, and that boundary layer thickness was an important parameter in predicting effectiveness of the holes. Heat transfer coefficient augmentation was highly dependent on the freestream turbulence levels as well as boundary layer thickness, and significant spatial variations were observed.

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