scholarly journals An Experiment Investigation of Film Cooling Effectivenes of Sister Hole of Cylindrical Shaped Hole Film Cooling Geometry on a Flat Plate Surface

2015 ◽  
Vol 773-774 ◽  
pp. 309-322
Author(s):  
Muhammad Haziq Md Yazid ◽  
Hamidon Salleh
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Operating Temperature ◽  
Cost Effective ◽  
Vital Role ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole

Gas turbines are widely used nowadays for aircraft propulsion and in land-based power generation or in the industrial application. The operating temperature of gas turbine has to be increased in order to increase their effectiveness. Thus, a cooling method known as film cooling is introduced to cool down the high operating temperature of the gas turbine. Film cooling is one of the effective methods in reducing the heat load to a turbine airfoil. This method is cost effective and by far the most common and widely researched method in the industry. Film cooling effectiveness plays a vital role in modern gas turbine technology. This present study will focus on sister holes that are attached to the primary holes at shallow angle of 30°, with 4 different blowing ratios ranging from 0.5 to 2.0. The roles of the different in blowing ratios are to observe the different values of film effectiveness presented by the sister holes design and to select the most effective blowing ratio that suits the design at shallow angle. From the results obtained, the usage of sister holes with shallow angle further increases the film cooling effectiveness particularly at low blowing ratio.

scholarly journals Experimental Study on Film Cooling Effectiveness of Shallow Hole with Upstream Sister Holes

2015 ◽  
Vol 773-774 ◽  
pp. 393-397
Author(s):  
Hamidon bin Salleh ◽  
Jing Zu Yee
Keyword(s):  
Experimental Study ◽  
Gas Turbine ◽  
Future Study ◽  
Thermal Efficiency ◽  
Film Cooling ◽  
Operating Temperature ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Secondary Air

In order to increase the thermal efficiency of a gas turbine, the operating temperature has to be increased. This increment may cause the material of the blade to melt. Film cooling is a good option to solve this problem. Various studies has been done on film cooling include the shallow hole and sister holes. The present study focused on an experimental of film cooling effectiveness on shallow hole of 20° with upstream sister holes with 3 blowing ratios which are 1.0, 15 and 2.0. The result showed significant improvement compared to shallow hole of 35°. The optimum blowing ratio is 1.5. Smaller shallow angle and upstream sister holes reduce the jet lifting effect of the secondary air flow. Future study can be done on shallow hole of shallow angle and blowing ratio around 1.5 in order to further improve the film cooling effectiveness.

An Experimental Study of Turbine Vane Film Cooling Using Endoscope-Based PSP Technique in a Single-Passage Wind Tunnel

2021 ◽  
Author(s):  
Kechen Wang ◽  
Hongyi Shao ◽  
Xu Zhang ◽  
Di Peng ◽  
Yingzheng Liu ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Gas Turbine ◽  
Film Cooling ◽  
Flux Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Single Passage ◽  
Pressure Sensitive ◽  
Shaped Hole

Abstract Limited optical access has been a challenge in gas-turbine related researches since the small blade pitch makes it difficult to arrange the camera at a proper viewing angle. In this paper, the application of an endoscopic system in a single-passage wind tunnel is presented. The film cooling effectiveness over the turbine vane’s pressure side with two types of holes was measured using the pressure-sensitive paint (PSP) technique. With the 7-7-7 shaped hole serving as the baseline, the sister shaped hole was compared side-by-side to examine its cooling performance at exit Ma = 0.84. Carbon dioxide (i.e., DR = 1.53) as coolant was discharged into the flow passage through two rows of holes (i.e., 4D spacing between holes and 1.5D spacing between rows) with blowing ratio (M) varied from 0.6 to 2.0. Through the implementation of the homography algorithm, the distorted coolant traces were recovered from the cambered surface. It was found that the film cooling effectiveness of both holes was greatly influenced by the blowing ratio. The sister shaped hole exhibited a relatively high effectiveness distribution at low M but its effectiveness decreased at high M due to the coolant jet detachment. In contrast, the 7-7-7 shaped hole demonstrated significantly higher effectiveness at high M, which can be attributed to the lower momentum flux ratio results of its larger exit area. The endoscope-based PSP technique and the obtained adiabatic effectiveness results may lay the foundation for other investigations and support other CFD studies in the gas turbine community.

Heat Transfer Coefficients and Film Cooling Effectiveness on the Squealer Tip of a Gas Turbine Blade

2003 ◽  
Vol 125 (4) ◽  
pp. 648-657 ◽  
Author(s):  
Jae Su Kwak ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Rotor Blade ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Heat Transfer Coefficients ◽  
Blowing Ratio

Experimental investigations were performed to measure the detailed heat transfer coefficients and film cooling effectiveness on the squealer tip of a gas turbine blade in a five-bladed linear cascade. The blade was a two-dimensional model of a first stage gas turbine rotor blade with a profile of the GE-E3 aircraft gas turbine engine rotor blade. The test blade had a squealer (recessed) tip with a 4.22% recess. The blade model was equipped with a single row of film cooling holes on the pressure side near the tip region and the tip surface along the camber line. Hue detection based transient liquid crystals technique was used to measure heat transfer coefficients and film cooling effectiveness. All measurements were done for the three tip gap clearances of 1.0%, 1.5%, and 2.5% of blade span at the two blowing ratios of 1.0 and 2.0. The Reynolds number based on cascade exit velocity and axial chord length was 1.1×106 and the total turning angle of the blade was 97.9 deg. The overall pressure ratio was 1.2 and the inlet and exit Mach numbers were 0.25 and 0.59, respectively. The turbulence intensity level at the cascade inlet was 9.7%. Results showed that the overall heat transfer coefficients increased with increasing tip gap clearance, but decreased with increasing blowing ratio. However, the overall film cooling effectiveness increased with increasing blowing ratio. Results also showed that the overall film cooling effectiveness increased but heat transfer coefficients decreased for the squealer tip when compared to the plane tip at the same tip gap clearance and blowing ratio conditions.

Experimental Investigation and Optimal Design on the Film Cooling Performance of Fan-Shaped Hole With Vortex Generator Fed by Crossflow

2021 ◽  
Author(s):  
Jie Wang ◽  
Chao Zhang ◽  
Xuebin Liu ◽  
Liming Song ◽  
Jun Li ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Film Cooling ◽  
Vortex Generator ◽  
Optimized Design ◽  
Combined Model ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole

Abstract Aiming at investigating the effects of crossflow and vortex generator on film cooling characteristics of fan-shaped hole, the film cooling performance was measured experimentally by infrared camera. The blowing ratio is fixed at 0.5 and 1.5. The Reynolds number of the mainstream based on the hole diameter remains at 7000 and the inlet Reynolds number of crossflow is 40000. The experimental results show that the film cooling performance becomes better when the blowing ratio increases from 0.5 to 1.5 for each model, and the film cooling performance becomes worse under the influence of crossflow. When the blowing ratio is 1.5, the area-averaged film cooling effectiveness of the fan-shaped hole model with vortex generator decreases by 16.6% because of the influence of crossflow. The combined model always performs better compared with the model without vortex generator under all working conditions. When the blowing ratio becomes 1.5, under the influence of crossflow, the area-averaged film cooling effectiveness of the combined model could increase by 14.8%, compared with the model without vortex generator. To further improve the film cooling performance, the global optimization algorithm based on the Kriging method and the CFD technology are coupled to optimize the combined model under crossflow condition at the high blowing ratio, and the optimized design is verified by experiments. The experimental results show that the area-averaged film cooling effectiveness of the optimized design increases by 17.8% compared with the reference model.

Implementation of Hole-Pair in Ramp to Improve Film Cooling Effectiveness on a Plain Surface

2020 ◽  
Author(s):  
Sadam Hussain ◽  
Xin Yan
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Density Ratio ◽  
Hole Pair ◽  
Cooling Effect ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cooling Hole ◽  
Plain Surface

Abstract Film cooling is one of the most critical technologies in modern gas turbine engine to protect the high temperature components from erosion. It allows gas turbines to operate above the thermal limits of blade materials by providing the protective cooling film layer on outer surfaces of blade against hot gases. To get a higher film cooling effect on plain surface, current study proposes a novel strategy with the implementation of hole-pair into ramp. To gain the film cooling effectiveness on the plain surface, RANS equations combined with k-ω turbulence model were solved with the commercial CFD solver ANSYS CFX11.0. In the numerical simulations, the density ratio (DR) is fixed at 1.6, and the film cooling effect on plain surface with different configurations (i.e. with only cooling hole, with only ramp, and with hole-pair in ramp) were numerically investigated at three blowing ratios M = 0.25, 0.5, and 0.75. The results show that the configuration with Hole-Pair in Ramp (HPR) upstream the cooling hole has a positive effect on film cooling enhancement on plain surface, especially along the spanwise direction. Compared with the baseline configuration, i.e. plain surface with cylindrical hole, the laterally-averaged film cooling effectiveness on plain surface with HPR is increased by 18%, while the laterally-averaged film cooling effectiveness on plain surface with only ramp is increased by 8% at M = 0.5. As the blowing ratio M increases from 0.25 to 0.75, the laterally-averaged film cooling effectiveness on plain surface with HPR is kept on increasing. At higher blowing ratio M = 0.75, film cooling effectiveness on plain surface with HPR is about 19% higher than the configuration with only ramp.

Film Cooling Investigation of a Slot-Based Diffusion Hole

2016 ◽  
Author(s):  
Bai-Tao An ◽  
Jian-Jun Liu ◽  
Si-Jing Zhou ◽  
Xiao-Dong Zhang ◽  
Chao Zhang
Keyword(s):  
Cross Section ◽  
Film Cooling ◽  
Rectangular Cross Section ◽  
Density Ratio ◽  
Vortex Structures ◽  
Cross Sectional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole

This paper presents a new configuration of discrete film hole, i.e., the slot-based diffusion hole. Retaining the similar diffusion features to a traditional diffusion hole, the slot-based diffusion hole transforms the cross section of circle for the traditional diffusion hole to a flattened rectangle with respect to the equivalent cross-sectional area. Consequently, the exit width of the new hole is effectively enlarged. To verify the film cooling effectiveness, a low speed flat plate experimental facility incorporated with Pressure Sensitive Paint (PSP) measurement technique was employed to obtain the adiabatic film cooling effectiveness. The experiments were performed with hole pitch to diameter ratio p/D=6 and density ratio DR=1.38. The blowing ratio was varied from M=0.5 to M=2.5. A fan-shaped hole and two slot-based diffusion holes were tested and compared. Three-dimensional numerical simulation was employed to analyze the flow field in detail. The experimental results showed that the area averaged effectiveness of two slot-based diffusion holes is significantly higher than that of the fan-shaped hole when the blowing ratio exceeds 1.0. The slot-based diffusion hole demonstrates the great advantage over the fan-shaped hole at hole exit and maintains this to far downstream. The numerical results showed that the ends shape of the flattened rectangular cross section has large influences on film distribution patterns and downstream vortex structures. The semi-circle and straight line ends shapes lead to a bi-peak and a single-peak effectiveness pattern, respectively. The optimal ends shape can regulate the vortex structures and improve the film cooling effectiveness further.

Simulation Film Cooling in the Leading Edge Region of a Turbine Blade (Trench Effect on Film Effectiveness from Cylinder in Crossflow)

2014 ◽  
Vol 554 ◽  
pp. 317-321
Author(s):  
Mohamad Rasidi Bin Pairan ◽  
Norzelawati Binti Asmuin ◽  
Hamidon bin Salleh
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Edge Region ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Hot Gas ◽  
Cooling Technique

Film cooling is one of the cooling techniques applied to the turbine blade. Gas turbine used film cooling technique to protect turbine blade from directly expose to the hot gas to avoid the blade from defect. The focus of this investigation is to investigate the effect of embedded three difference depth of trench at coolant holes geometry. Comparisons are made at four difference blowing ratios which are 1.0, 1.25 and 1.5. Three configuration leading edge with depth Case A (0.0125D), Case B (0.0350D) and Case C (0.713D) were compared to leading edge without trench. Result shows that as blowing ratio increased from 1.0 to 1.25, the film cooling effectiveness is increase for leading edge without trench and also for all cases. However when the blowing ratio is increase to 1.5, film cooling effectiveness is decrease for all cases. Overall the Case B with blowing ratio 1.25 has the best film cooling effectiveness with significant improvement compared to leading edge without trench and with trench Case A and Case C.

Influence of Coolant Density on Turbine Blade Film-Cooling With Compound-Angle Shaped Holes

2012 ◽  
Author(s):  
Kevin Liu ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Density Ratio ◽  
Flux Ratio ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole ◽  
Compound Angle

Adiabatic film-cooling effectiveness is examined systematically on a typical high pressure turbine blade by varying three critical flow parameters: coolant blowing ratio, coolant-to-mainstream density ratio, and freestream turbulence intensity. Three average coolant blowing ratios 1.0, 1.5, and 2.0; three coolant density ratios 1.0, 1.5, and 2.0; two turbulence intensities 4.2% and 10.5%, are chosen for this study. Conduction-free pressure sensitive paint (PSP) technique is used to measure film-cooling effectiveness. Three foreign gases — N2 for low density, CO2 for medium density, and a mixture of SF6 and Argon for high density are selected to study the effect of coolant density. The test blade features 45° compound-angle shaped holes on the suction side and pressure side, and 3 rows of 30° radial-angle cylindrical holes around the leading edge region. The inlet and the exit Mach number are 0.27 and 0.44, respectively. Reynolds number based on the exit velocity and blade axial chord length is 750,000. Results reveal that the PSP is a powerful technique capable of producing clear and detailed film effectiveness contours with diverse foreign gases. As blowing ratio exceeds the optimum value, it induces more mixing of coolant and mainstream. Thus film-cooling effectiveness reduces. Greater coolant-to-mainstream density ratio results in lower coolant-to-mainstream momentum and prevents coolant to lift-off; as a result, film-cooling increases. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of suction side. Results are also correlated with momentum flux ratio and compared with previous studies. It shows that compound shaped hole has the greatest optimum momentum flux ratio, and then followed by axial shaped hole, compound cylindrical hole, and axial cylindrical hole.

A Numerical Investigation on the Performance of Novel Sister Shaped Single-Hole Configurations for Film Cooling Flow

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam A. Jubran
Keyword(s):  
Film Cooling ◽  
The Novel ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Blowing Ratio ◽  
Single Hole ◽  
Attached Flow ◽  
Shaped Hole ◽  
Lift Off

The film cooling performance using novel sister shaped single-hole (SSSH) schemes are numerically investigated in the present study. The downstream, upstream and up/downstream SSSH configurations are formed by merging the discrete sister holes to the primary injection hole through a series of specific orientations. The obtained results are compared with a conventional cylindrical hole and a forward diffused shaped hole. The RANS simulations are performed using the realizable k-ε model with the standard wall function. Results are presented for low and high blowing ratios of 0.25 and 1.5, respectively. The film cooling effectiveness is notably increased for the novel shaped holes, particularly at the high blowing ratio of 1.5. Furthermore, a considerable decrease in the jet lift-off has been achieved for the proposed film hole geometries, wherein fully attached flow to the wall surface is observed for the upstream and up/downstream SSSH schemes.

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