Experimental investigation on film cooling performance of pressure side in annular cascades

2011 ◽  
Vol 20 (2) ◽  
pp. 119-126 ◽  
Author(s):  
Guoqing Li ◽  
Hongwu Deng
Keyword(s):  
Experimental Investigation ◽  
Film Cooling ◽  
Pressure Side ◽  
Cooling Performance

An Experimental Investigation of a New Hybrid Film Cooling Scheme

2010 ◽  
Author(s):  
M. Ghorab ◽  
I. Hassan ◽  
T. Lucas
Keyword(s):  
Experimental Investigation ◽  
Film Cooling ◽  
Hybrid Film ◽  
Density Ratio ◽  
Thermochromic Liquid Crystal ◽  
Hybrid Scheme ◽  
Cooling Performance ◽  
Average Heat ◽  
Bending Effect ◽  
Turbine Airfoils

This paper presents an experimental investigation of the film cooling performance of a New Hybrid Film Cooling Scheme using Thermochromic Liquid Crystal technique. The new scheme has been designed to improve the film cooling performance of gas turbine airfoils. The scheme includes two consecutive film hole configurations with interior bending. The cooling performance of the new scheme was analyzed across blowing ratios of 0.5, 1.0 and 1.5, at a density ratio of 0.94. The results showed that the new scheme enhanced the local and the laterally averaged film cooling performance in terms of effectiveness, and net heat flux reduction in compared to other film hole configurations. The bending effect of the new scheme throttled the secondary flow causing it to spread widely over the downstream surfaces, hence enhancing the film cooling performance at low and high blowing ratios. The hybrid scheme provided an average heat transfer ratio near unity over the downstream surfaces at low and high blowing ratios.

Experimental Investigation of Sweeping Jet Film Cooling in a Transonic Turbine Cascade

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Mohammad A. Hossain ◽  
Munevver E. Asar ◽  
James W. Gregory ◽  
Jeffrey P. Bons
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Mach Number ◽  
Film Cooling ◽  
Total Pressure ◽  
Suction Surface ◽  
Cooling Performance ◽  
Aerodynamic Loss ◽  
Comparison Results ◽  
Shaped Hole

Abstract The sweeping jet (SJ) film cooling hole has shown promising cooling performance compared to the standard shaped hole in low-speed conditions. The present work demonstrates the first attempt of SJ film cooling at an engine relevant Mach number. An experimental investigation was conducted to study the SJ film cooling on a nozzle guide vane suction surface. A well-established additive manufacturing technique commonly known as stereolithography (SLA) was utilized to design a transonic, engine representative vane geometry in which a row of SJ holes was used on the vane suction surface. Experiments were performed in a linear transonic cascade at an exit Mach number of 0.8 and blowing ratios of BR = 0.25–2.23. The measurement of heat transfer was conducted with the transient IR method, and the convective heat transfer coefficient (HTC) and adiabatic film cooling effectiveness were estimated using a dual linear regression technique (DLRT). Aerodynamic loss measurements were also performed with a total pressure Kiel probe at 0.25Cax downstream of the exit plane of the vane cascade. Experiments were also conducted for a baseline-shaped hole (777-hole) for a direct comparison. Results showed that the SJ hole has a wider coolant spreading in the lateral direction near the hole exit due to its sweeping motion that improves the overall cooling performance particularly at high blowing ratios (BR > 1). Aerodynamic loss measurement suggested that the SJ hole has a comparable total pressure loss to the 777-shaped hole.

Computational Study on Pressure Side Film Cooling and Flow Structure

2013 ◽  
Author(s):  
Radheesh Dhanasegaran ◽  
Girish Venkatachalapathy ◽  
Nagarajan Gnanasekaran
Keyword(s):  
Flow Structure ◽  
Film Cooling ◽  
Computational Study ◽  
Pressure Side ◽  
Cooling Performance ◽  
Pressure Surface ◽  
Blowing Ratio ◽  
Commercial Code ◽  
Cylindrical Holes ◽  
Specific Geometry

A computational investigation is carried out to understand the film cooling performance and flow phenomenon on a pressure side of gas turbine airfoil. A specific geometry with multiple rows of cylindrical holes is considered on the pressure surface and opposite to which a flat surface is kept so as to avoid effect of imposed flow conditions. Meshing of the present model is done by using GAMBIT. Computations are carried out with K-epsilon Realizable model available in the commercial code FLUENT. The film cooling performance is discussed with flow structure followed by the effectiveness distribution on the pressure surface. The blowing ratio is varied from 0.4–2.4 and it is found that, at very low blowing ratio cases in the initial part of the pressure surface higher effectiveness values are observed but at higher blowing ratio these values become very low whereas close to the trailing edge side the effectiveness distribution is just the reverse. It was found that the optimum blowing ratio was close to unity where better flow and temperature distribution were observed.

Experimental Study of Sister Hole Film Cooling Performance in a Rotating Flat Plate Model

2015 ◽  
Author(s):  
Hong Wu ◽  
Huichuan Cheng ◽  
Yulong Li ◽  
Shuiting Ding
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Rotation Number ◽  
Film Cooling ◽  
Suction Side ◽  
Pressure Side ◽  
Plate Model ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

Film cooling performance of a sister hole was investigated in a flat plate model by applying Thermochromic Liquid Crystal (TLC) technique under the stationary and rotating conditions. The flat plate model is installed in the test section. The sister hole include one main hole and two additional side holes with the smaller diameter in the spanwise direction. The diameter of the main hole is 4 mm and the injection angle is 30°. The density ratio of coolant to mainstream is 1.05. The Reynolds number (ReD) based on the velocity of mainstream and the diameter of the main hole are 2300, 3400 and 4500. Four rotational speeds of 200, 400, 600 and 800 rpm are conducted on both pressure side (trailing wall) and suction side (leading wall) with the blowing ratio varying from 0.14 to 3.5. The effects of blowing ratio, Reynolds number (ReD) and rotation number are mainly analyzed according to film coverage and film cooling effectiveness. The results show that the film performance firstly increases then decreases with the rising of blowing ratio, the optimal blowing ratio is about M=0.5. The film cooling performance is improved with higher Reynolds number (ReD). Under the rotation condition, the film trajectory has an obvious centrifugal deflection which can be enhanced by higher rotation number on the pressure side, and the film deflection moves a little centripetally on the suction side. The film cooling effectiveness on the suction side increases with the rising of rotation number and it is higher than that on the pressure side.

Experimental Investigation of Film Cooling Performance for a New Shaped Hole at the Leading Edge

2014 ◽  
Author(s):  
Tarek Elnady ◽  
Ibrahim Hassan
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Density Ratio ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Stagnation Line ◽  
Cooling Performance

An experimental investigation has been performed to study the film cooling performance of a smooth expansion exit at the leading edge of a gas turbine vane. A two-dimensional cascade has been employed to measure the cooling performance of the proposed expansion using the transient Thermochromatic Liquid Crystal technique. One row of cylindrical holes, located on the stagnation line, is investigated with two expansion levels, 2d and 4d, in addition to the standard hole. The air is injected at 90° and 60° inclination angle relative to the vane surface at four blowing ratios ranging from 1 to 2 at a 0.9 density ratio. The Mach number and the Reynolds number based on the cascade exit velocity and the axial chord are 0.23 and 1.4E5, respectively. The detailed local heat transfer coefficient over both the pressure side and the suction side are presented in addition to the lateral-averaged normalized heat transfer coefficient. The proposed expansion provides a lower heat transfer coefficient compared with the standard cylindrical hole over the investigated blowing ratios. Combining the heat transfer coefficient with the corresponding cooling effectiveness, previously presented, the smooth expansion shows a significant reduction in the heat load with more uniform distribution of the coolant over the leading edge region. The strong confrontation between the coolant jet and the mainstream, in case of 90° injection, yields a strong dispersion of the coolant with higher heat transfer coefficient and high thermal load over the vane surface.

Experimental Investigations of the Film Cooling Performance of a Micro-Tangential-Jet Scheme on a Gas Turbine Vane: Part 1 — Effectiveness

2012 ◽  
Author(s):  
O. Hassan ◽  
I. Hassan
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Experimental Investigations ◽  
Stream Velocity ◽  
Pressure Side ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Turbine Vane

This paper presents experimental investigations of the film cooling effectiveness performance of a Micro-Tangential-Jet (MTJ) Film cooling scheme on a gas turbine vane using transient Thermochromic Liquid Crystal (TLC) technique. The MTJ scheme is a micro-shaped scheme designed so that the secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. The film cooling performance of one row of holes on both pressure and suction sides were investigated at a blowing ratio ranging from 0.5 to 1.5 on the pressure side and 0.25 to 0.625 on the suction side. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 5 on the pressure side and 6.5 on the suction side. The turbulence intensity during all investigations was 8.5%. Minor changes in the Mach number distribution around the airfoil surface were observed due to the presence of the MTJ scheme, compared with the case with no MTJ scheme. The investigations showed great film cooling performance for the MTJ scheme, high effectiveness values, and excellent lateral jet spreading. A 2-D coolant film was observed in the results, which is a characteristic of the continuous slot schemes only. The presence of this 2-D film layer helps minimize the rate of mixing between the main and coolant streams and provides uniform thermal loads on the surface. Furthermore, it was noticed that the rate of effectiveness decay on the suction side was less than that on the pressure side, while the lateral jet spreading on the pressure side was better than that of the suction side. The main disadvantage of the MTJ scheme is the increased pressure drop.

Experimental Investigation of Double Rows Film Cooling on Vane Pressure Side

2012 ◽  
Author(s):  
T. Elnady ◽  
I. Hassan ◽  
L. Kadem ◽  
T. Lucas
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Density Ratio ◽  
Radius Of Curvature ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
The Heat Transfer Coefficient

An experimental investigation has been performed to study the effect of hole shape and position on the cooling performance of a gas turbine stator. Two rows of laid-back fan-shaped holes are placed on the pressure side of a scaled vane in a two-dimensional cascade and compared with two identical rows of standard cylindrical exit. Both hole shapes have the same base diameter and were investigated at three different blowing ratios (1, 1.35, and 1.7) with the same coolant flow rate used in each case. The experiments are conducted for the first row of holes only, then for the second row only, and finally for both two rows together at a 0.9 density ratio. The mainstream inlet Reynolds number based on the true chord is 1.4E5 and the exit Mach number is 0.23. The local distributions of the heat transfer coefficient and film cooling effectiveness are obtained using a transient TLC technique. The second row of holes, with by a higher local radius of curvature, shows a 40% decrease in the cooling effectiveness as well as a 10% increase in the heat transfer coefficient near downstream of the hole compared with that obtained by the first hole. The double injection provides a slight increase in the cooling effectiveness and a lower heat transfer coefficient due to the favorable interaction between both injections.

Experimental Investigations of the Effect of Scheme Exit Height and Double Row Injection on the Film Cooling Performance of a Micro Tangential Jet Scheme: Part I — Pressure Side

2015 ◽  
Author(s):  
O. Hassan ◽  
I. Hassan
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Average Density ◽  
Hole Diameter ◽  
Experimental Investigations ◽  
Pressure Side ◽  
Thermochromic Liquid Crystal ◽  
Double Row ◽  
Cooling Performance

This paper presents experimental investigations of the effect of scheme exit height and double jet injection on the film cooling performance of a Micro-Tangential-Jet (MTJ) scheme. The investigations were conducted over a gas turbine vane pressure side using the transient Thermochromic Liquid Crystal technique. The suction side investigations are presented in Part II of the present paper. The MTJ scheme is a micro-shaped scheme designed so that the micro-sized secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. In order to investigate the effect of scheme exit height, one row of the MTJ scheme with 1.0 hole diameter exit height and another row with 1.5 hole diameter exit height were investigated. Meanwhile, to investigate the effect of double injection, one row of the MTJ scheme in staggered arrangement with one row of fan-shaped scheme was investigated. The investigations were conducted at various blowing ratios, calculated based on the scheme exit area. The average density ratio, turbulence intensity and Reynolds number were 0.93, 8.5, and 1.4E+5, respectively. The investigations showed that the smaller the exit height, the better the film cooling performance. Meanwhile, double injecting the secondary stream from MTJ and shaped schemes did not result in significant film cooling enhancement due to the enhanced turbulence over the vane surface.

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