Three-Dimensional Flow Prediction and Improvement of Holes Arrangement of a Film-Cooled Turbine Blade Using a Feature-Based Jet Model

2006 ◽  
Vol 129 (2) ◽  
pp. 258-268 ◽  
Author(s):  
André Burdet ◽  
Reza S. Abhari
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Three Dimensional ◽  
Good Prediction ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Numerical Predictions ◽  
Flow Prediction ◽  
Feature Based

A feature-based jet model has been proposed for use in three-dimensional (3D) computational fluid dynamics (CFD) prediction of turbine blade film cooling. The goal of the model is to be able to perform computationally efficient flow prediction and optimization of film-cooled turbine blades. The model reproduces in the near-hole region the macroflow features of a coolant jet within a Reynolds-averaged Navier-Stokes framework. Numerical predictions of the 3D flow through a linear transonic film-cooled turbine cascade are carried out with the model, with a low computational overhead. Different cooling holes arrangements are computed, and the prediction accuracy is evaluated versus experimental data. It is shown that the present model provides a reasonably good prediction of the adiabatic film-cooling effectiveness and Nusselt number around the blade. A numerical analysis of the interaction of coolant jets issuing from different rows of holes on the blade pressure side is carried out. It is shown that the upward radial migration of the flow due to the passage secondary flow structure has an impact on the spreading of the coolant and the film-cooling effectiveness on the blade surface. Based on this result, a new arrangement of the cooling holes for the present case is proposed that leads to a better spanwise covering of the coolant on the blade pressure side surface.

3D Flow Prediction and Improvement of Holes Arrangement of a Film-Cooled Turbine Blade Using a Feature-Based Jet Model

2006 ◽  
Author(s):  
Andre´ Burdet ◽  
Reza S. Abhari
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Good Prediction ◽  
Pressure Side ◽  
3D Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Numerical Predictions ◽  
Flow Prediction ◽  
Feature Based

A feature-based jet model has been proposed for use in 3D CFD prediction of turbine blade film cooling. The goal of the model is to be able to perform computationally efficient flow prediction and optimization of film-cooled turbine blades. The model reproduces in the near hole region the macro flow features of a coolant jet within a Reynolds-Averaged Navier Stokes (RANS) framework. Numerical predictions of the 3D flow through a linear transonic film-cooled turbine cascade are carried out with the model, with a low computational overhead. Different cooling holes arrangement are computed and the prediction accuracy is evaluated versus experimental data. It shown that the present model provides a reasonably good prediction of the adiabatic film-cooling effectiveness and Nusselt number around the blade. A numerical analysis of the interaction of coolant jets issuing from different rows of holes on the blade pressure side is carried out. It is shown that the upward radial migration of the flow due to the passage secondary flow structure has an impact on the spreading of the coolant and the film cooling effectiveness on the blade surface. Based on this result, a new arrangement of the cooling holes for the present case is proposed that leads to a better spanwise covering of the coolant on the blade pressure side surface.

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 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.

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

2007 ◽  
Author(s):  
Zhihong Gao ◽  
Diganta P. Narzary ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Suction Side ◽  
Steady Increase ◽  
Pressure Side ◽  
Wake Effect ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Compound Angle

The film cooling effectiveness on the surface of a high pressure turbine blade is measured using the Pressure Sensitive Paint (PSP). Four rows of fan-shaped, laid-back compound angled cooling holes are distributed on the pressure side while two such rows are provided on the suction side of the blade. The coolant is only injected to either the pressure side or suction side of the blade at five average blowing ratios from 0.4 to 1.5. Presence of wake due to 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 a progressing wake. Effect of wake is recorded at four phase locations with equal intervals along the pitch-wise direction. The free stream Reynolds number, based on the axial chord length and the exit velocity, is 750,000 and the inlet and the exit Mach numbers are 0.27 and 0.44, respectively, resulting in a blade pressure ratio of 1.14. Results reveal that the tip leakage vortices and endwall vortices sweep the coolant film on the suction side to the midspan region. The fan-shaped, laid-back compound angled holes produce good coolant film coverage on the suction side except for those regions affected by the secondary vortices. Due to the concave surface, the coolant trace is short and effectiveness level is low on the pressure surface. However, the pressure side acquires relatively uniform film coverage with the design of multiple rows of cooling holes. The presence of stationary upstream wake results in lower film cooling effectiveness on the blade surface. Variation of blowing ratio from 0.4 to 1.5 shows steady increase in effectiveness on the pressure side or the suction side for a given wake rod phases locations. The compound angle shaped holes outperform the compound angle cylindrical holes by the elevated film cooling effectiveness particularly at higher blowing ratios.

A One-Dimensional Analytical Method for Turbine Blade Preliminary Cooling Design

2016 ◽  
Author(s):  
Chen Li ◽  
Jian-jun Liu
Keyword(s):  
Mass Flow Rate ◽  
Turbine Blade ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
One Dimensional ◽  
Cooling Design

The turbine blade cooling design is a complex procedure including one-dimensional preliminary cooling design, detailed two-dimensional design and fluid network analyses, and three-dimensional conjugate heat transfer and FEM predictions. Frequent alteration and modification of the cooling configurations make it unpractical to obtain all of three-dimensional design results quickly. Preliminary cooling design deals mainly with the coolant requirements and can be knitted into fluid network to look up the expected cooling structural style to promote three-dimensional geometry design. Previous methods to estimate the coolant requirements of the whole turbine blade in the preliminary cooling design were usually based on the semi-empirical air-cooled blade data. This paper combines turbine blade internal and external cooling, and presents a one-dimensional theoretical analytical method to investigate blade cooling performance, assuming that the coolant temperature increases along the blade span. Firstly, a function of non-dimensional cooling mass flow rate is derived to describe the new relationship between adiabatic film cooling effectiveness and overall cooling effectiveness. Secondly, a new variable related to film cooling is found to estimate the required adiabatic film cooling effectiveness without using the empirical correlations. Finally, a theoretical calculation about the relationship between non-dimensional cooling mass flow rate and overall cooling effectiveness well corresponds to semi-empirical air-cooled blade data within regular range of cooling efficiency. The currently proposed method is also a useful tool for the blade thermal analysis and the sensitivity analysis of coolant requirements to various design parameters. It not only can provide all the possible options at the given gas and coolant inlet temperatures to meet the design requirement, but also can give the third boundary conditions for calculating the blade temperature field. It’s convenient to use the heat transfer characteristic of internal cooling structures to estimate the coolant mass flow rate and the channel hydraulic diameter for both convection cooling and film cooling.

Effect of Unsteady Wake on Film-Cooling Effectiveness Distribution on a Gas Turbine Blade With Compound Shaped Holes

2007 ◽  
Author(s):  
Diganta P. Narzary ◽  
Zhihong Gao ◽  
Shantanu Mhetras ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Suction Side ◽  
Intensity Level ◽  
Pressure Side ◽  
Wake Effect ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cylindrical Holes

The effect of fan-shaped, laid-back compound angled cooling holes placed along the span of a fully-cooled high pressure turbine blade in a 5-blade linear cascade on film cooling effectiveness is studied using the Pressure Sensitive Paint (PSP) technique. Four rows of shaped film cooling holes are provided on the pressure side while two such rows are provided on the suction side of the blade. Three rows of cylindrical holes are drilled at 30° to the surface on the leading edge to capture the effect of showerhead film coolant injection. The coolant is injected at four different average blowing ratios of 0.3, 0.6, 0.9 and 1.2. Presence of wake due to upstream vanes is studied by placing a periodic set of rods upstream of the test blade. The wake is generated using 4.8mm diameter rods. The wake rods can be clocked by changing their stationary positions in front of the test blade to simulate a progressing wake. Effect of wake is recorded at four phase locations with equal intervals. The free stream Reynolds number, based on the axial chord length and the exit velocity, is 750,000 and the inlet and the exit Mach numbers are 0.27 and 0.44, respectively resulting in a blade pressure ratio of 1.14. Turbulence intensity level at the cascade inlet is 6% with an integral length scale of around 5cm. Results show that the fan-shaped, laid-back compound angled holes produce uniform and wide coolant coverage on the suction side except for those regions affected by the passage and tip leakage vortices. The advantage of compound shaped hole design is seen from the higher effectiveness values on the suction side compared to that of the compound cylindrical holes. The presence of a stationary upstream wake can result in lower film cooling effectiveness on the blade surface. Variation of blowing ratio from 0.3 to 1.2 show more or less uniform increment in effectiveness increase on the pressure side, whereas on the suction side, the increment shows signs of saturation beyond M = 0.6.

Influence of Coolant Density on Turbine Blade Film-Cooling Using Pressure Sensitive Paint Technique

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
Diganta P. Narzary ◽  
Kuo-Chun Liu ◽  
Akhilesh P. Rallabandi ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Suction Side ◽  
Pressure Side ◽  
Pressure Sensitive Paint ◽  
Freestream Turbulence ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive

Adiabatic film-cooling effectiveness is examined on a high-pressure turbine blade by varying three critical engine parameters, viz., coolant blowing ratio, coolant-to-mainstream density ratio, and freestream turbulence intensity. Three average coolant blowing ratios (BR=1.2, 1.7, and 2.2 on the pressure side and BR=1.1, 1.4, and 1.8 on the suction side), three average coolant density ratios (DR=1.0, 1.5, and 2.5), and two average freestream turbulence intensities (Tu=4.2% and 10.5%) are considered. Conduction-free pressure sensitive paint (PSP) technique is adopted 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 two rows of cylindrical film-cooling holes on the suction side (45 deg compound), 4 rows on the pressure side (45 deg compound) and 3 around the leading edge (30 deg radial). The inlet and the exit Mach numbers are 0.24 and 0.44, respectively. The Reynolds number of the mainstream flow is 7.5×105 based on the exit velocity and blade chord length. Results suggest that the PSP is a powerful technique capable of producing clear and detailed film-effectiveness contours with diverse foreign gases. Large improvement on the pressure side and moderate improvement on the suction side effectiveness is witnessed when blowing ratio is raised from 1.2 to 1.7 and 1.1 to 1.4, respectively. No major improvement is seen thereafter with the downstream half of the suction side showing drop in effectiveness. The effect of increasing coolant density is to increase effectiveness everywhere on the pressure surface and suction surface except for the small region on the suction side, xss/Cx<0.2. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of the suction side where significant improvement in effectiveness is seen.

Impact of Flowfield Unsteadiness on Film Cooling of a High Pressure Turbine Blade

2010 ◽  
Author(s):  
Paul Vitt ◽  
Chad Iverson ◽  
Malak F. Malak ◽  
Jong S. Liu
Keyword(s):  
High Pressure ◽  
Steady State ◽  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Flow Unsteadiness ◽  
The Impact

A key factor in gas turbine blade operation is flow unsteadiness generated by the vane as the blade passes behind it, and the impact of this variation on the aerodynamic performance of the blade has been well studied. The objective of the current study was to examine the impact of this flow unsteadiness on film cooling effectiveness on the airfoil. A Honeywell research single-stage high-pressure cooled turbine was selected as an engine-representative geometry. Both steady-state and transient stage calculations were completed using fully cooled vane and blade models. One area of interest was the impact of the vane passing on the local film hole flow rates, so the blade model included the leading edge impingement chamber as well as detailed film cooling holes in the analysis. Results from the calculations showed a dramatic change in the predicted film cooling on the blade surface in two primary areas. At the leading edge, the steady-state model predicted low local film effectiveness due to the stagnation line falling between showerhead film rows, whereas the time-averaged unsteady analysis showed an even distribution of film at the leading edge. On the pressure side, the steady model predicted effective film coverage downstream of the gill holes. In the unsteady analysis, the low momentum mixed gas and film stream along the forward portion of the pressure side was highly disturbed by the vane unsteadiness, and time-averaging the results indicated a significant reduction in overall film cooling effectiveness. The results show that considering the unsteady operating environment of the blade is very important during design and optimization of the blade thermal protection system.

Heat Transfer Coefficients and Film-Cooling Effectiveness on a Gas Turbine Blade Tip

2003 ◽  
Vol 125 (3) ◽  
pp. 494-502 ◽  
Author(s):  
Jae Su Kwak ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blade Tip

The detailed distributions of heat transfer coefficient and film cooling effectiveness on a gas turbine blade tip were measured using a hue detection based transient liquid crystals technique. Tests were performed on a five-bladed linear cascade with blow-down facility. 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 97.7°. 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%. The blade model was equipped with a single row of film cooling holes at both the tip portion along the camber line and near the tip region of the pressure side. All measurements were made at the three different tip gap clearances of 1.0%, 1.5%, and 2.5% of blade span and the three blowing ratios of 0.5, 1, and 2. Results showed that, in general, heat transfer coefficient and film effectiveness increased with increasing tip gap clearance. As blowing ratio increased, heat transfer coefficient decreased, while film effectiveness increased. Results also showed that adding pressure side coolant injection would further decrease the blade tip heat transfer coefficient but increase film-cooling effectiveness.

Influence of Coolant Density on Turbine Blade Film-Cooling Using Pressure Sensitive Paint Technique

2010 ◽  
Author(s):  
Diganta P. Narzary ◽  
Kuo-Chun Liu ◽  
Akhilesh P. Rallabandi ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Suction Side ◽  
Pressure Side ◽  
Pressure Sensitive Paint ◽  
Freestream Turbulence ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive

Adiabatic film-cooling effectiveness is examined on a high pressure turbine blade by varying three critical engine parameters, viz., coolant blowing ratio, coolant-to-mainstream density ratio and freestream turbulence intensity. Three average coolant blowing ratios (BR = 1.2, 1.7, and 2.2 on the pressure side and BR = 1.1, 1.4, and 1.8 on the suction side), three average coolant density ratios (DR = 1.0, 1.5, and 2.5), and two average freestream turbulence intensities (Tu = 4.2% and 10.5%) are considered. Conduction-free Pressure Sensitive Paint (PSP) technique is adopted 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 2 rows of cylindrical film-cooling holes on the suction side (45° compound), 4 rows on the pressure side (45° compound) and 3 around the leading edge (30° radial). The inlet and the exit Mach numbers are 0.24 and 0.44, respectively. Reynolds number of the mainstream flow is 7.5E105 based on the exit velocity and blade chord length. Results suggest that the PSP is a powerful technique capable of producing clear and detailed film effectiveness contours with diverse foreign gases. Large improvement on the pressure side and moderate improvement on the suction side effectiveness is witnessed when blowing ratio is raised from 1.2 to 1.7 and 1.1 to 1.4, respectively. No major improvement is seen thereafter with the downstream half of the suction side showing drop in effectiveness. The effect of increasing coolant density is to increase effectiveness everywhere on the pressure surface and suction surface except for the small region on the suction side, xss/Cx&lt;0.2. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of the suction side where significant improvement in effectiveness is seen.

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