A Detailed Study of the Interaction Between Two Rows of Cooling Holes

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Y. Jiang ◽  
L. Capone ◽  
P. Ireland ◽  
E. Romero
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
High Efficiency ◽  
Nonlinear Effects ◽  
Suction Side ◽  
Complex Problem ◽  
Correct Prediction ◽  
Blowing Ratio ◽  
Key Factor ◽  
Plate Geometry

An optimal design of film cooling is a key factor in the effort of producing high-efficiency gas turbine. Understanding of the fluid dynamics interaction between cooling holes can help engineers to improve overall thermal effectiveness. Correct prediction through modeling is a very complex problem since multiple phenomena are involved such as mixing, turbulence, and heat transfer. The present work performs an investigation of different cooling configurations ranging from single hole up to two rows. The main objective is to evaluate the double-rows interaction and the effect on film cooling. Strong nonlinear effects are underlined by different simulations, while varying blowing ratio (BR) and geometrical configuration of cooling holes. Meanwhile an initial analysis is performed using flat plate geometry, verification and validation is then extended to realistic stage of high pressure (HP) turbine. Multiple cooling holes configurations are embedded on the pressure side (PS) and suction side (SS) of the single stage. The main outcome is the verification of the thermal effectiveness improvement obtained by cooling jets interaction of multiple rows design. The effects of curvature surface and frame of reference rotation are also evaluated, underlying the differences with standard flat plate test cases.

A Detailed Study of the Interaction Between Two Rows of Cooling Holes

2017 ◽  
Author(s):  
Y. Jiang ◽  
L. Capone ◽  
P. Ireland ◽  
E. Romero
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
High Efficiency ◽  
Nonlinear Effects ◽  
Complex Problem ◽  
Correct Prediction ◽  
Test Cases ◽  
Blowing Ratio ◽  
Key Factor ◽  
Plate Geometry

An optimal design of film cooling is a key factor in the effort of producing high efficiency gas turbine. Understanding of the fluid dynamics interaction between cooling holes can help engineers to improve overall thermal effectiveness. Modelling and correct prediction is a very complex problem, since the multiple phenomena involved, such as: mixing, turbulence and heat transfer. The present work performs an investigation of different cooling configurations ranging from single hole up to two rows. The main objective is to evaluate the double-rows interaction and the effect on film cooling. Strong nonlinear effects are underlined by different simulations, while varying blowing ratio and geometrical configuration of cooling holes. Meanwhile an initial analysis is performed using flat plate geometry, verification and validation is then extended to realistic stage of high pressure turbine. Multiple cooling holes configurations are embedded on the pressure and suction sides of the single stage. The main outcome is the verification of the thermal effectiveness improvement obtained by cooling jets interaction of multiple rows design. The effects of curvature surface and frame of reference rotation are also evaluated, underlying the differences with standard flat plate test cases.

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.

Film cooling characteristics on a grooved surface with different injection orientation angles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Yang ◽  
Guangchao Li ◽  
Jianyong Zhu
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Orientation Angle ◽  
Hole Injection ◽  
Blowing Ratio ◽  
Reverse Trend ◽  
Grooved Surface ◽  
Shaped Hole

Abstract The film effectiveness was investigated on a grooved surface with the injection orientation angles of 30°, 90°, and 150° at the blowing ratios of 0.5, 0.8, 1.1, and 1.4. The injection orientation angle and the groove on the surface caused the effect of the various and irregular shaped hole injection due to the different orientation injection. The results showed that the new phenomenon of film effectiveness distributions was found on the grooved surface compared with the flat plate case. Film effectiveness distributions for the β = 30° were found to be the discontinuous strips. The surface averaged film effectiveness with the orientation angle of 30° was found to decrease with the increase of the blowing ratio. Additionally, the reverse trend was observed with the orientation angle of 150°. The film effectiveness with the orientation angle of 90° only slightly changed with the increase of the blowing ratio.

Film cooling characteristics on a grooved surface with different injection orientation angles

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Peng Yang ◽  
Guangchao Li ◽  
Jianyong Zhu
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Orientation Angle ◽  
Hole Injection ◽  
Blowing Ratio ◽  
Reverse Trend ◽  
Grooved Surface ◽  
Shaped Hole

AbstractThe film effectiveness was investigated on a grooved surface with the injection orientation angles of 30°, 90°, and 150° at the blowing ratios of 0.5, 0.8, 1.1, and 1.4. The injection orientation angle and the groove on the surface caused the effect of the various and irregular shaped hole injection due to the different orientation injection. The results showed that the new phenomenon of film effectiveness distributions was found on the grooved surface compared with the flat plate case. Film effectiveness distributions for the β = 30° were found to be the discontinuous strips. The surface averaged film effectiveness with the orientation angle of 30° was found to decrease with the increase of the blowing ratio. Additionally, the reverse trend was observed with the orientation angle of 150°. The film effectiveness with the orientation angle of 90° only slightly changed with the increase of the blowing ratio.

The Effect of Freestream Turbulence on Film Cooling Adiabatic Effectiveness

2002 ◽  
Author(s):  
James E. Mayhew ◽  
James W. Baughn ◽  
Aaron R. Byerley
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Main Flow ◽  
Freestream Turbulence ◽  
Coverage Area ◽  
Liquid Crystal Thermography ◽  
Blowing Ratio ◽  
Adiabatic Effectiveness ◽  
Cooling Air

The film-cooling performance of a flat plate in the presence of low and high freestream turbulence is investigated using liquid crystal thermography. High-resolution distributions of the adiabatic effectiveness are determined over the film-cooled surface of the flat plate using the hue method and image processing. Three blowing rates are investigated for a model with three straight holes spaced three diameters apart, with density ratio near unity. High freestream turbulence is shown to increase the area-averaged effectiveness at high blowing rates, but decrease it at low blowing rates. At low blowing ratio, freestream turbulence clearly reduces the coverage area of the cooling air due to increased mixing with the main flow. However, at high blowing ratio, when much of the jet has lifted off in the low turbulence case, high freestream turbulence turns its increased mixing into an asset, entraining some of the coolant that penetrates into the main flow and mixing it with the air near the surface.

Numerical Investigation of Coolant-to-Mainstream Scaling Parameters With Film Cooling on Pressure and Suction Side of a Gas Turbine Blade

2017 ◽  
Author(s):  
Lingyu Zeng ◽  
Xueying Li ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Momentum Flux ◽  
Velocity Ratio ◽  
Density Ratio ◽  
Flux Ratio ◽  
Suction Side ◽  
Pressure Side ◽  
Blowing Ratio ◽  
Adiabatic Effectiveness

Most experiments of blade film cooling are conducted with density ratio lower than that of turbine conditions. In order to accurately model the performance of film cooling under a high density ratio, choosing an appropriate coolant to mainstream scaling parameter is necessary. The effect of density ratio on film cooling effectiveness on the surface of a gas turbine twisted blade is investigated from a numerical point of view. One row of film holes are arranged in the pressure side and two rows in the suction side. All the film holes are cylindrical holes with a pitch to diameter ratio P/d = 8.4. The inclined angle is 30°on the pressure side and 34° on the suction side. The steady solutions are obtained by solving Reynolds-Averaged-Navier-Stokes equations with a finite volume method. The SST turbulence model coupled with γ-θ transition model is applied for the present simulations. A film cooling experiment of a turbine vane was done to validate the turbulence model. Four different density ratios (DR) from 0.97 to 2.5 are studied. To independently vary the blowing ratio (M), momentum flux ratio (I) and velocity ratio (VR) of the coolant to the mainstream, seven conditions (M varying from 0.25 to 1.6 on the pressure side and from 0.25 to 1.4 on the suction side) are simulated for each density ratio. The results indicate that the adiabatic effectiveness increases with the increase of density ratio for a certain blowing ratio or a certain momentum flux ratio. Both on the pressure side and suction side, none of the three parameters listed above can serve as a scaling parameter independent of density ratio in the full range. The velocity ratio provides a relative better collapse of the adiabatic effectiveness than M and I for larger VRs. A new parameter describing the performance of film cooling is introduced. The new parameter is found to be scaled with VR for nearly the whole range.

Experimental Investigation of Turbine Phantom Cooling on Suction Side With Combustor-Turbine Leakage Gap Flow and Endwall Film Cooling

2012 ◽  
Author(s):  
Yang Zhang ◽  
Xin Yuan
Keyword(s):  
Film Cooling ◽  
Incidence Angle ◽  
Suction Side ◽  
Leakage Flow ◽  
Airfoil Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Coolant Injection ◽  
Passage Vortex

The film cooling injection on Hp turbine component surface is strongly affected by the complex flow structure in the nozzle guide vane or rotor blade passages. The action of passage vortex near endwall surface could dominate the film cooling effectiveness distribution on the component surfaces. The film cooling injections from endwall and airfoil surface are mixed with the passage vortex. Considering a small part of the coolant injection from endwall will move towards the airfoil suction side and then cover some area, the interaction between the coolants injected from endwall and airfoil surface is worth investigating. Though the temperature of coolant injection from endwall increases after the mixing process in the main flow, the injections moving from endwall to airfoil suction side still have the potential of second order cooling. This part of the coolant is called “Phantom cooling flow” in the paper. A typical scale-up model of GE-E3 Hp turbine NGV is used in the experiment to investigate the cooling performance of injection from endwall. Instead of the endwall itself, the film cooling effectiveness is measured on the airfoil suction side. This paper is focused on the combustor-turbine interface gap leakage flow and the coolant from fan-shaped holes moving from endwall to airfoil suction side. The coolant flow is injected at a 30deg angle to the endwall surface both from a slot and four rows of fan-shaped holes. The film cooling holes on the endwall and the leakage flow are used simultaneously. The blowing ratio and incidence angle are selected to be the parameters in the paper. The experiment is completed with the blowing ratio changing from M = 0.7 to M = 1.3 and the incidence angle varying from −10deg to +10deg, with inlet Reynolds numbers of Re = 3.5×105 and an inlet Mach number of Ma = 0.1.

scholarly journals Flat Plate and Turbine Vane Film-Cooling Performance with Laid-Back Fan-Shaped Holes

2019 ◽  
Vol 4 (2) ◽  
pp. 14 ◽  
Author(s):  
Tommaso Bacci ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Density Ratio ◽  
Pressure Sensitive Paint ◽  
Cooling Performance ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Turbine Vane ◽  
Experimental Works ◽  
Lift Off

Shaped holes are considered as an effective solution to enhance gas turbine film-cooling performance, as they allow to increase the coolant mass-flux, while limiting the detrimental lift-off phenomena. A great amount of work has been carried out in past years on basic flat plate configurations while a reduced number of experimental works deals with a quantitative assessment of the influence of curvature and vane pressure gradient. In the present work PSP (Pressure Sensitive Paint) technique is used to detail the adiabatic effectiveness generated by axial shaped holes with high value of Area Ratio close to 7, in three different configurations with the same 1:1 scale: first of all, a flat plate configuration is examined; after that, the film-cooled pressure and suction sides of a turbine vane model are investigated. Tests were performed varying the blowing ratio and imposing a density ratio of 2.5 . The experimental results are finally compared to the predictions of two different correlations, developed for flat plate configurations.

Experimental Study on Film Cooling Flow Characteristics of Turbine Stator Blade at Different Setting Angles

2012 ◽  
Vol 614-615 ◽  
pp. 592-595
Author(s):  
Ling Zhang ◽  
Hai Rui Dong ◽  
Guo Liang Wen
Keyword(s):  
Film Cooling ◽  
Effective Means ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Suction Side ◽  
Pressure Side ◽  
Blowing Ratio ◽  
Turbine Stator ◽  
Setting Angle ◽  
Stator Blade

The technology of film cooling is one of the most effective means of protecting the turbine blades. In this paper, flow structures of the turbine stator blade with six hole-rows at different blowing ratio（M=0.5, 1.0 and 1.5）and setting angles（β=40°, 50°, 60°, 70°, 80° and 90°） was measured by PIV in piston flow type of low-speed wind tunnel laboratory. Velocity was analyzed. Results show that: velocity gradient of suction side was much higher than pressure side and increased with setting angle reduction; Adherence of film is influenced by setting angle and blowing ratio, when M=1.0 and β=70° anchorage dependent is best and suction side is greater than pressure side.

Numerical Approach at Flat Plate for Predicting the Film Cooling Effectiveness Part A: Effect Blowing Ratio

2018 ◽  
Vol 16 ◽  
pp. 30-44 ◽  
Author(s):  
Farouk Kebir ◽  
Azzeddine Khorsi
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Film Cooling ◽  
Thermal Stresses ◽  
Free Stream ◽  
Turbine Blades ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Free Stream Turbulence ◽  
Blowing Ratio

Film cooling is vital for gas turbine blades to protect them from thermal stresses and high temperatures due to the hot gas flow in the blade surface. Film cooling is applied to almost all external surfaces associated with aerodynamic profiles that are exposed to hot combustion gases such as main bodies, end-walls, blade tips and leading edges. In a review of the literature, it was found that there are strong effects of free-stream turbulence, surface curvature and hole shape on film cooling performance also blowing ratio. The performance of the film cooling is difficult to predict due to the inherent complex flow fields along the surfaces of the airfoil components in the turbine engines. From all what we introducing the film cooling is reviewed through a discussion of the analyses methodologies, a physical description, and the various influences on film-cooling performance. Initially Computational analysis was done on a flat plate with hole inclined at 55° to the surface plate. This study focuses on the efficient computation of film cooling flows with three blowing ratio. The numerical results show the effectiveness cooling and heat transfer behavior with increasing injection blowing ratio M (0.5, 1, and 1.5). The influence of increased blade film cooling can be assessed via the values of Nusselt number in terms of reduced heat transfer to the blade. Predictions of film effectiveness are compared with experimental results for a circular jet at blowing ratios ranging from 0.5, 1.0 and 1.5. The present results are obtained at a free stream turbulence of 10%, which are the typical conditions upstream of the effectiveness is generally lower for a large stream-wise angle of 55°.

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