Effect of Rotation on Flow Field and Film Cooling Effectiveness in Film-Cooled Turbine Rotors

2014 ◽  
Vol 31 (4) ◽  
Author(s):  
Xiaocheng Zhu ◽  
Liangliang Liu ◽  
Feng Yuan
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Film Cooling ◽  
Suction Side ◽  
Wake Region ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Surface ◽  
Blowing Ratio ◽  
Low Speed Wind Tunnel

AbstractExperimental and numerical investigations of flow field in a film-cooled turbine model under stationary and rotating conditions in a low-speed wind tunnel are conducted. The effects of different blowing ratios (M = 1.5, 2) on the flow field are studied. Results revealed a secondary flow near the blade surface in the wake region behind the jet hole. Compared with the stationary turbine, there exists centrifugal force and Coriolis force in the flow field of the rotating turbine, and these forces cause changes in the flow field in the rotating turbine. The effect of rotation on the flow field and film cooling effectiveness in the Y-Z planes on the pressure side is stronger than on the suction side, and results in lower film cooling effectiveness on the pressure surface of the rotating turbine blade compared with the stationary turbine. As the blowing ratio increases, the secondary flow in the wake region will become stronger, thereby enlarging the range of the wake.

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 Prediction and Measurement of Film Cooling Effectiveness for a First-Stage Turbine Vane Shroud

1990 ◽  
Author(s):  
D. Granser ◽  
T. Schulenberg
Keyword(s):  
Secondary Flow ◽  
Film Cooling ◽  
Three Dimensional ◽  
Suction Side ◽  
Computer Code ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Equations ◽  
Numerical Predictions ◽  
Numerical Effort

After compressor discharge air has initially been used to cool the heat shields of the hot gas inlet casing, it can subsequently be employed for film cooling of the first-stage vane shrouds. Since the flow field near these shrouds is three-dimensional, the film cooling effectiveness cannot be predicted correctly by common two-dimensional codes. The secondary flow transports the film from the pressure side to the suction side where it can even climb up the airfoil to cool its trailing section. Such film cooling effectiveness was first investigated experimentally in a linear vane cascade at atmospheric pressure. The temperatures and static pressure levels at the adiabatic shrouds, as well as the temperature measurements within the vane cascade, are reported for different cooling film blowing rates. In addition, the secondary flow was analysed numerically using a partially-parabolic computer code for 3D viscous flows. It involves mutual interaction of the boundary layer with the mainstream. The secondary flow can also be modelled with this algorithm, which requires less numerical effort than solving the fully 3D elliptic flow equations. The numerical results of the experiment and numerical predictions are compared. In addition, the application of these results to a high-temperature gas turbine is presented.

Film Cooling Effectiveness Distribution on First-Stage Vane Endwall With and Without Leading-Edge Fillets: Part I—Effect of Leading Edge Geometry

2011 ◽  
Author(s):  
Yang Zhang ◽  
Xin Yuan
Keyword(s):  
Film Cooling ◽  
Flow Direction ◽  
Leading Edge ◽  
Suction Side ◽  
Axial Direction ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Edge Geometry ◽  
Blade Cascade

The paper is focused on the effect of leading edge airfoil geometry on endwall film cooling. Fillets placed at the junctions of the leading edge and the endwall are used in investigation. Three types of fillet profiles are tested, and the results are compared with baseline geometry without fillet. The design of the fillet is based on the suggestion by previous literature data indicating that sharp is effective in controlling the secondary flow. Three types of sharp slope fillet with the length to height ratio of 2.8, 1.2 and 0.5 are made using stereo lithography (SLA) and assessed in the experiment. Distributed with the approximately inviscid flow direction, four rows of compound angle laidback fan-shaped holes are arranged on the endwall to form full covered coolant film. The four rows of fanshaped holes are inclined 30 deg to the endwall surface and held an angle of 0, 30, 45 and 60 deg to axial direction respectively. The fanshaped holes have a lateral diffusion angle of 10 deg from the hole-centerline and a forward expansion angle of 10 deg to the endwall surface. The Reynolds number based on the axial chord and inlet velocity of the free-stream flow is 3.5*105, and the testing is done in a four-blade cascade with low Mach number condition (0.1 at the inlet) while the blowing ratio of the coolant through the discrete holes varies from 0.4 to 1.2. The film-cooling effectiveness distributions are obtained using the PSP (pressure sensitive paint) technique, by which the effect of different fillet geometry on passage induced flow and coolant is shown. The present paper compares the film cooling effectiveness distributions in a baseline blade cascade with three similar blades with different leading edge by adding fillets. The results show that with blowing ratio increasing, the film cooling effectiveness increases on the endwall. For specific blowing ratio, the effects of leading edge geometries could be illustrated as follows. The baseline geometry provides the best film cooling performance near leading edge pressure side. As for the leading edge suction side, the best leading edge geometry depends on the blowing ratio. The longfillet is the more effective in controlling horseshoe vortex at low blowing ratio, but for the high blowing ratio shortfillet and mediumfillet are better.

Flow Dynamics and Film Cooling Effectiveness on a Non-Axisymmetric Contour Endwall in a Two-Dimensional Cascade Passage

2009 ◽  
Author(s):  
Gazi I. Mahmood ◽  
Ross Gustafson ◽  
Sumanta Acharya
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Film Cooling ◽  
Free Stream ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Blowing Ratio

The measured flow field and temperature field near a three-dimensional asymmetric contour endwall employed in a linear blade cascade are presented with and without film-cooling flow on the endwall. Flow field temperature and Nusselt number distributions along the asymmetric endwall with wall heating and no film-cooling flow are also reported to show local high heat transfer region on the endwall and justify the locations of the coolant holes. Adiabatic film-cooling effectiveness along the endwall is then measured to indicate the local effects of the coolant jets. The near endwall flow field and temperature field provide the coolant flow behavior and the interaction of coolant jets with the boundary layer flow. Thus, the local film-cooling effectiveness can be explained with the coolant jet trajectories. The measurements are obtained at the Reynolds number of 2.30×105 based on blade actual chord and inlet velocity, coolant-to-free stream temperature ratio of 0.93, and coolant-to-free stream density ratio of 1.06. The cascade employs the hub side blade section and passage geometry of the first stage rotor of GE-E3 turbine engine. The contour endwall profile is employed on the bottom endwall only in the cascade. The blowing ratio of the film-cooling flow varies from 1.0 to 2.4 from 71 discrete cylindrical holes located in the contour endwall. The three-dimensional profile of the endwall varies in height in both the pitchwise and axial directions. The flow field is quantified with the streamwise vorticity and turbulent intensity, pitchwise static pressure difference, flow yaw angle, and pitchwise velocity. Both the flow field and temperature data indicate that the coolant jets cover more distance in the pitchwise and axial direction in the passage as the blowing ratio increases. Thus, the local and average film-cooling effectiveness increase with the blowing ratio.

Effect of Hole Diameter on Nozzle Endwall Film Cooling and Associated Phantom Cooling

2015 ◽  
Author(s):  
Luzeng Zhang ◽  
Juan Yin ◽  
Kevin Liu ◽  
Moon Hee-Koo
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Leading Edge ◽  
Suction Side ◽  
Hole Diameter ◽  
Two Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Blowing Ratio

Flow fields near the turbine nozzle endwall are highly complex due to the passage vortices and endwall cross flows. Consequently, it is challenging to provide proper cooling to the endwall surfaces. An effective way to cool the endwall is to have film cooling holes forward of the leading edge, often called “inlet-film cooling”. This paper presents the results of an experimental investigation on how the film hole diameter affects the film effectiveness on nozzle endwall and associated phantom cooling effectiveness on airfoil suction side. The measurements were conducted in a high speed linear cascade, which consists of three nozzle vanes and four flow passages. Double staggered rows of film injections, which were located upstream from the nozzle leading edge, provided cooling to the contoured endwall surfaces. Film cooling effectiveness on the endwall surface and corresponding phantom cooling effectiveness on the airfoil suction side were measured separately with a Pressure Sensitive Paint (PSP) technique through the mass transfer analogy. Four different film hole diameters with the same injection angle and the same pitch to diameter ratio were studied for up to six different MFR’s (mass flow ratios). Two dimensional film effectiveness distributions on the endwall surface and two dimensional phantom cooling distributions on the airfoil suction side are presented. Film/phantom cooling effectiveness distributions are pitchwise/spanwise averaged along the axial direction and also presented. The results indicate that both the endwall film effectiveness and the suction side phantom cooling effectiveness increases with the hole diameter (as decreases in blowing ratio for a given MFR) up to a specific diameter, then starts decreasing. An optimal value of the film hole diameter (blowing ratio) for the given injection angle is also suggested based on current study.

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.

Film-Cooling on a Gas Turbine Blade Pressure Side or Suction Side With Compound Angle Shaped Holes

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Zhihong Gao ◽  
Diganta P. Narzary ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Surface ◽  
Compound Angle

The film-cooling effectiveness on the surface of a high pressure turbine blade is measured using the pressure sensitive paint technique. Compound angle laidback fan-shaped holes are used to cool the blade surface with four rows on the pressure side and two rows on the suction side. The coolant injects to one side of the blade, either pressure side or suction side. The presence of wake due to the upstream vanes is simulated by placing a periodic set of rods upstream of the test blade. The wake rods can be clocked by changing their stationary positions to simulate progressing wakes. The effect of wakes is recorded at four phase locations along the pitchwise direction. The freestream Reynolds number, based on the axial chord length and the exit velocity, is 750,000. The inlet and exit Mach numbers are 0.27 and 0.44, respectively, resulting in a pressure ratio of 1.14. Five average blowing ratios ranging from 0.4 to 1.5 are tested. Results reveal that the tip-leakage vortices and endwall vortices sweep the coolant on the suction side to the midspan region. The compound angle laidback fan-shaped holes produce a good film coverage on the suction side except for the regions affected by the secondary vortices. Due to the concave surface, the coolant trace is short and the effectiveness level is low on the pressure surface. However, the pressure side acquires a relatively uniform film coverage with the multiple rows of cooling holes. The film-cooling effectiveness increases with the increasing average blowing ratio for either side of coolant ejection. The presence of stationary upstream wake results in lower film-cooling effectiveness on the blade surface. The compound angle shaped holes outperform the compound angle cylindrical holes by the elevated film-cooling effectiveness, particularly at higher blowing ratios.

scholarly journals Experimental Study Of Short Hole Film-Cooling

2021 ◽  
Author(s):  
Mohammed A. Gandhi
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Film Cooling ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Blowing Ratio ◽  
Lift Off ◽  
Low Speed Wind Tunnel

An experimental study was conducted to investigate the film cooling effectiveness of a few configurations of short injection holes: single row, double row and both of the preceding cases with an upstream ramp placed at two different locations. In order to perform the above study, a wind-tunnel facility was assembled to facilitate in the successful culmination of the experiments. The focus of the study was to determine the cooling provided by the short injection holes at a variety of blowing ratios and whether adding an extra row of holes, upstream of the first row would make a difference. For the second part, a ramp was placed upstream of the single and double row configuration to help improve cooling . All of the experiments were performed in a low speed wind-tunnel with a mainstream velocity of 8 m/s and a turbulence insity of 3.3%. Higher blowing ratios were ineffective in improving film-cooling effectiveness due to jet lift-off. Two rows of holes increased the cooling effectiveness by 200%, when compared to single row configurations at the same blowing ratio without ramps. Upstream ramps provided significant improvement in the near hole region of the injection holes.

scholarly journals Experimental Study Of Short Hole Film-Cooling

2021 ◽  
Author(s):  
Mohammed A. Gandhi
Keyword(s):  
Experimental Study ◽  
Wind Tunnel ◽  
Film Cooling ◽  
Double Row ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Blowing Ratio ◽  
Lift Off ◽  
Low Speed Wind Tunnel

An experimental study was conducted to investigate the film cooling effectiveness of a few configurations of short injection holes: single row, double row and both of the preceding cases with an upstream ramp placed at two different locations. In order to perform the above study, a wind-tunnel facility was assembled to facilitate in the successful culmination of the experiments. The focus of the study was to determine the cooling provided by the short injection holes at a variety of blowing ratios and whether adding an extra row of holes, upstream of the first row would make a difference. For the second part, a ramp was placed upstream of the single and double row configuration to help improve cooling . All of the experiments were performed in a low speed wind-tunnel with a mainstream velocity of 8 m/s and a turbulence insity of 3.3%. Higher blowing ratios were ineffective in improving film-cooling effectiveness due to jet lift-off. Two rows of holes increased the cooling effectiveness by 200%, when compared to single row configurations at the same blowing ratio without ramps. Upstream ramps provided significant improvement in the near hole region of the injection holes.

Experimental Investigation of Film Cooling Performance on Blade Endwall with Diffusion Slot Holes and Stator-Rotor Purge Flow

2021 ◽  
pp. 1-28
Author(s):  
Zhi-Qiang Yu ◽  
Jianjun Liu ◽  
Chen Li ◽  
Baitao An ◽  
Guang-Yao Xu
Keyword(s):  
Film Cooling ◽  
Flow Direction ◽  
Cross Flow ◽  
Orientation Angle ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Pressure Surface ◽  
Blowing Ratio ◽  
Shaped Hole

Abstract This paper focuses on the influences of the discrete hole shape and layout on the blade endwall film cooling effectiveness. The diffusion slot hole was first applied to the blade endwall and compared with the fan-shaped hole. The effect of upstream purge slot injection on the film cooling performance of the discrete hole was also investigated. Experiments were performed in a linear cascade with a exit Reynolds number of 2.64×105. The film cooling effectiveness on the blade endwall were measured by the pressure sensitive paint technique. Results indicate that the diffusion slot hole significantly increases the film cooling effectiveness on the blade endwall compared to the fan-shaped hole, especially at high blowing ratio. The maximum relative increment of the cooling effectiveness is over 40%. The layout with the discrete holes arranged lining up with the tangent direction of the blade profile offset curves exhibits a comparable film cooling effectiveness with the layout with the discrete holes arranged according to the cross-flow direction. The film cooling effectiveness on the pressure surface corner is remarkably enhanced by deflecting the hole orientation angle towards the pressure surface. The combination of purge slot and diffusion slot holes supplies a full coverage film cooling for the entire blade endwall at coolant mass flow ratio of the purge slot of 1.5% and blowing ratio of 2.5. In addition, the slot injection leads to a non-negligible influence on the cooling performance of the discrete holes near the separation line.

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