Numerical Study of a Rotating Blade Platform With Film Cooling From Cavity Purge Flow in a 1-1/2 Turbine Stage

2006 ◽  
Author(s):  
Huitao Yang ◽  
Hamn-Ching Chen ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Turbine Stage ◽  
Transfer Coefficients ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Rotating Speed ◽  
Rotating Blade ◽  
Purge Flow

Numerical simulations were performed to predict the effect of cavity purge flow on the rotating blade platform in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a non-equilibrium wall function. Simulations were carried out with a sliding mesh for the rotor under three rotating speeds (2000, 2550 and 3000 rpm) and three purge-to-mainstream mass flow ratios (0.5%, 1% and 1.5%) to investigate the effects of rotating speed and coolant purging rate on the rotating blade platform film cooling. The adiabatic film cooling effectiveness was evaluated using the adiabatic wall temperatures with and without coolant purging to examine the true effect of coolant protection. The film cooling effectiveness increases with increasing coolant purging flow ratio from 0.5% to 1.5% of mainstream. Higher rotating speed also enhances film cooling effectiveness for the range of rotating speed considered. The predicted laterally averaged adiabatic film cooling effectiveness is in good agreement with the corresponding experiment data except for the platform leading edge region. However, the detailed effectiveness distribution on the platform is not well predicted by this study. In addition, the detailed instantaneous film cooling effectiveness and the associated heat transfer coefficients for four different time phases are also reported.

Prediction of Film Cooling and Heat Transfer on a Rotating Blade Platform With Stator-Rotor Purge and Discrete Film-Hole Flows in a 1-1/2 Turbine Stage

2007 ◽  
Author(s):  
H. Yang ◽  
Z. Gao ◽  
H. C. Chen ◽  
J. C. Han ◽  
M. T. Schobeiri
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Turbine Stage ◽  
Transfer Coefficients ◽  
Work Process ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Heat Transfer Coefficients ◽  
Rotating Blade ◽  
Purge Flow

Numerical simulations were performed to predict the film cooling effectiveness and heat transfer coefficient distributions on a rotating blade platform with stator-rotor purge flow and downstream discrete film-hole flows in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a non-equilibrium wall function. Simulations were carried out with sliding mesh for the rotor under three rotating speeds (2000, 2550, and 3000 rpm) to investigate the effects of rotation and stator-rotor interaction on the rotor blade platform purge flow cooling and discrete-hole film cooling and heat transfer. The adiabatic film cooling effectiveness and heat transfer coefficients were calculated using the adiabatic wall temperatures with and without coolant to examine the true coolant protection excluding the effect of turbine work process. The stator-rotor interaction strongly impacts the purge slot film cooling and heat transfer at the platform leading portion, while only slightly affects the downstream discrete-hole film cooling near the platform trailing portion. In addition, the effect of turbine work process on the film cooling effectiveness and the associated heat transfer coefficients have been reported.

Prediction of Film Cooling and Heat Transfer on a Rotating Blade Platform With Stator-Rotor Purge and Discrete Film-Hole Flows in a 1-12 Turbine Stage

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
H. Yang ◽  
Z. Gao ◽  
H. C. Chen ◽  
J. C. Han ◽  
M. T. Schobeir
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Turbine Stage ◽  
Transfer Coefficients ◽  
Work Process ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Heat Transfer Coefficients ◽  
Rotating Blade ◽  
Purge Flow

Numerical simulations were performed to predict the film cooling effectiveness and heat transfer coefficient distributions on a rotating blade platform with stator-rotor purge flow and downstream discrete film-hole flows in a 1-12 turbine stage using a Reynolds stress turbulence model together with a nonequilibrium wall function. Simulations were carried out with sliding mesh for the rotor under three rotating speeds (2000 rpm, 2550 rpm, and 3000 rpm) to investigate the effects of rotation and stator-rotor interaction on the rotor blade-platform purge flow cooling and discrete-hole film cooling and heat transfer. The adiabatic film cooling effectiveness and heat transfer coefficients were calculated using the adiabatic wall temperatures with and without coolant to examine the true coolant protection excluding the effect of turbine work process. The stator-rotor interaction strongly impacts the purge slot film cooling and heat transfer at the platform leading portion while only slightly affects the downstream discrete-hole film cooling near the platform trailing portion. In addition, the effect of turbine work process on the film cooling effectiveness and the associated heat transfer coefficients have been reported.

Numerical Prediction of Film Cooling and Heat Transfer on the Leading Edge of a Rotating Blade With Two Rows Holes in a 1-1/2 Turbine Stage at Design and Off Design Conditions

2005 ◽  
Author(s):  
Huitao Yang ◽  
Hamn-Ching Chen ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Leading Edge ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Rotating Speed ◽  
Rotating Blade

Numerical simulations were performed to predict the film cooling effectiveness and the associated heat transfer coefficient on the leading edge of a rotating blade in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a non-equilibrium wall function. Simulations were performed for both the design and off-design conditions to investigate the effects of blade rotation on the leading edge film cooling effectiveness and heat transfer coefficient distributions. It was found that the tilt stagnation line on the leading edge of rotor moves from the pressure side to the suction side, and the instantaneous coolant streamlines shift from the suction side to the pressure side with increasing rotating speed. This trend was supported by the experimental results. The result also showed that the heat transfer coefficient increases, but film cooling effectiveness decreases with increasing rotating speed. In addition, the unsteady characteristics of the film cooling and heat transfer at different time phases, as well as different rotating speeds, were also reported.

Numerical Study of the Film Cooling With Discrete-Hole Arrangement on a Cut Back Squealer Blade Tip

2015 ◽  
Author(s):  
Xiang Zhang ◽  
Zhong Yang ◽  
Shuqing Tian ◽  
Haiteng Ma
Keyword(s):  
Mass Flow ◽  
Film Cooling ◽  
Numerical Study ◽  
Pressure Side ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blade Tip ◽  
Cavity Floor

Detailed numerical investigations of film cooling effectiveness are conducted for the holes on the tip cavity floor and near the tip pressure side. The tested blade tip is a squealer with the trailing rim wall cut to allow the accumulated coolant in the cavity to escape and cool the trailing edge. The heat transfer coefficients on the un-cooled flat and cutback squealer blade tip are studied with numerical and experimental methods. Three dust purging holes with different diameters are arranged along the camber line, which forms the basic cooled case (PG case). Additional six tip cavity holes are arranged on cavity floor near the suction side rim (PG-TF case). Another row of angled twenty-one holes is arranged along the pressure side just below the tip based on the PG case (PG-PSF case). The coolant supply pressure ratios are controlled to be 1, 1.11, and 1.22 respectively, offering local blowing ratio from 0 to 2.5. Results show that the dust purging flow cooling performance increases with the cavity depth. Discrete holes on the cavity floor offer a well-distributed coolant, which refines the cooling effect on the cavity floor. The PG-PSF case with cooling holes on the pressure side has the best overall cooling performance with more coolant consumed, when PR ≥ 1.22. However, maintaining the same coolant mass flow the PG-TF case has the best cooling performance, and the margin between PG-TF and PG-PSF case decreases with mass flow. The moving shroud cases reveal that blade movement will cause significant negative impacts on film cooling effectiveness.

An Experimental and Numerical Study on the Aerothermal Characteristics of a Ribbed Transonic Squealer-Tip Turbine Blade With Purge Flow

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
A. Arisi ◽  
J. Phillips ◽  
W. F. Ng ◽  
S. Xue ◽  
H. K. Moon ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Purge Flow

Detailed heat transfer coefficient (HTC) and film cooling effectiveness (Eta) distribution on a squealer-tipped first stage rotor blade were measured using an infrared technique. The blade tip design, obtained from the Solar Turbines, Inc., gas turbine, consists of double purge hole exits and four ribs within the squealer cavity, with a bleeder exit port on the pressure side close to the trailing edge. The tests were carried out in a transient linear transonic wind tunnel facility under land-based engine representative Mach/Reynolds number. Measurements were taken at an inlet turbulent intensity of Tu = 12%, with exit Mach numbers of 0.85 (Reexit = 9.75 × 105) and 1.0 (Reexit = 1.15 × 106) with the Reynolds number based on the blade axial chord and the cascade exit velocity. The tip clearance was fixed at 1% (based on engine blade span) with a purge flow blowing ratio, BR = 1.0. At each test condition, an accompanying numerical study was performed using Reynolds-averaged Navier–Stokes (RANS) equations solver ansys fluent to further understand the tip flow characteristics. The results showed that the tip purge flow has a blocking effect on the leakage flow path. Furthermore, the ribs significantly altered the flow (and consequently heat transfer) characteristics within the squealer-tip cavity resulting in a significant reduction in film cooling effectiveness. This was attributed to increased coolant–leakage flow mixing due to increased recirculation within the squealer cavity. Overall, the peak HTC on the cavity floor increased with exit Mach/Reynolds number.

An Experimental and Numerical Study on the Aerothermal Characteristics of a Ribbed Transonic Squealer-Tip Turbine Blade With Purge Flow

2015 ◽  
Author(s):  
A. Arisi ◽  
J. Phillips ◽  
W. F. Ng ◽  
S. Xue ◽  
H. K. Moon ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Numerical Study ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Purge Flow

Detailed heat transfer coefficient (HTC) and film cooling effectiveness (Eta) distribution on a squealer tipped first stage rotor blade were measured using an infrared (IR) technique. The blade tip design, obtained from a Solar Turbines Inc. gas turbine, consisted of double purge hole exits and four ribs within the squealer cavity, with a bleeder exit port on the pressure side close to the trailing edge. The tests were carried out in a transient linear transonic wind tunnel facility under land-based engine representative Mach/Reynolds number. Measurements were taken at an inlet turbulent intensity of Tu = 12%, with exit Mach numbers of 0.85 (Reexit=9.75×105) and 1.0 (Reexit = 1.15×106) with the Reynolds number based on the blade axial chord and the cascade exit velocity. The tip clearance was fixed at 1% (based on engine blade span) with a purge flow blowing ratio BR = 1.0. At each test condition, an accompanying numerical study was performed using Reynolds Averaged Navier Stokes (RANS) equations solver ANSYS Fluent to further understand the tip flow characteristics. The results showed that the tip purge flow has a blocking effect on the leakage flow path. Furthermore, the ribs significantly altered the flow (and consequently heat transfer) characteristics within the squealer tip cavity resulting in a significant reduction in film cooling effectiveness. This was attributed to increased coolant-leakage flow mixing due to increased recirculation within the squealer cavity. Overall, the peak heat transfer coefficient on the cavity floor increased with exit Mach/Reynolds number.

Influence of Coolant Density on Turbine Platform Film-Cooling With Stator–Rotor Purge Flow and Compound-Angle Holes

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Kevin Liu ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Fundamental Parameters ◽  
Blowing Ratio ◽  
Purge Flow ◽  
Cylindrical Holes ◽  
Exit Mach Number ◽  
Compound Angle

A detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform. The platform was cooled by purge flow from a simulated stator–rotor seal combined with discrete hole film-cooling. The cylindrical holes and laidback fan-shaped holes were accessed in terms of film-cooling effectiveness. This paper focuses on the effect of coolant-to-mainstream density ratio on platform film-cooling (DR = 1 to 2). Other fundamental parameters were also examined in this study—a fixed purge flow of 0.5%, three discrete-hole film-cooling blowing ratios between 1.0 and 2.0, and two freestream turbulence intensities of 4.2% and 10.5%. Experiments were done in a five-blade linear cascade with inlet and exit Mach number of 0.27 and 0.44, respectively. Reynolds number of the mainstream flow was 750,000 and was based on the exit velocity and chord length of the blade. The measurement technique adopted was the conduction-free pressure sensitive paint (PSP) technique. Results indicated that with the same density ratio, shaped holes present higher film-cooling effectiveness and wider film coverage than the cylindrical holes, particularly at higher blowing ratios. The optimum blowing ratio of 1.5 exists for the cylindrical holes, whereas the effectiveness for the shaped holes increases with an increase of blowing ratio. Results also indicate that the platform film-cooling effectiveness increases with density ratio but decreases with turbulence intensity.

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.

Numerical Investigation of Effects of Blockage, Inclination Angle, and Hole-Size on Film Cooling Effectiveness at Concave Surface

2021 ◽  
Vol 143 (2) ◽  
Author(s):  
Fu-qiang Wang ◽  
Jian Pu ◽  
Jian-hua Wang ◽  
Wei-dong Xia
Keyword(s):  
Film Cooling ◽  
Pressure Loss ◽  
Numerical Study ◽  
Density Ratio ◽  
Concave Surface ◽  
Blockage Ratio ◽  
Coverage Area ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle

Abstract Film-hole can be often blocked by thermal-barrier coatings (TBCs) spraying, resulting in the variations of aerodynamic and thermal performances of film cooling. In this study, a numerical study of the blockage effect on the film cooling effectiveness of inclined cylindrical-holes was carried out on a concave surface to simulate the airfoil pressure side. Three typical blowing ratios (BRs) of 0.5, 1.0, and 1.5 were chosen at an engine-similar density ratio (DR) of 2.0. Two common inclination angles of 30 deg and 45 deg were designed. The blockage ratios were adjusted from 0 to 20%. The results indicated the blockage could enhance the penetration of film cooling flow to the mainstream. Thus, the averaged effectiveness and coolant coverage area were reduced. Moreover, the pressure loss inside of the hole was increased. With the increase of BR, the decrement of film cooling effectiveness caused by blockage rapidly increased. At BR = 1.5, the decrement could be acquired up to 70% for a blockage ratio of 20%. The decrement of film cooling effectiveness caused by blockage was nearly nonsensitive to the injection angle; however, the larger angle could generate the higher increment of pressure loss caused by blockage. A new design method for the couple scheme of film cooling and TBC was proposed, i.e., increasing the inlet diameter according to the blockage ratio before TBC spraying. In comparison with the original unblocked-hole, the enlarged blocked-hole not only kept the nearly same area-averaged effectiveness but also reduced slightly the pressure loss inside of the hole. Unfortunately, application of enlarged blocked-hole at large BR could lead to a more obvious reduction of effectiveness near hole-exit, in comparison with the original common-hole.

Film Cooling Effectiveness on a Rotating Turbine Platform Using Pressure Sensitive Paint Technique

2007 ◽  
Author(s):  
A. Suryanarayanan ◽  
B. Ozturk ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
Film Cooling ◽  
Gas Injection ◽  
Turbine Rotor ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Coolant Injection ◽  
Purge Flow ◽  
Effects Of Rotation

Film cooling effectiveness is measured on a rotating turbine blade platform for coolant injection through discrete holes using pressure sensitive paint technique (PSP). Most of the existing literatures provide information only for stationary end-walls. The effects of rotation on the platform film cooling effectiveness are not well documented. Hence, the existing 3-stage turbine research facility at TPFL, Texas A&M University was re-designed and installed to enable coolant gas injection on the 1st stage rotor platform. Two distinct coolant supply loops were incorporated into the rotor to facilitate separate feeds for upstream cooling using stator-rotor gap purge flow and downstream discrete-hole film cooling. As a continuation of the previously published work involving stator-rotor gap purge cooling, this study investigates film cooling effectiveness on the 1st stage rotor platform due to coolant gas injection through nine discrete holes located downstream within the passage region. Film cooling effectiveness is measured for turbine rotor frequencies of 2400rpm, 2550rpm and 3000rpm corresponding to rotation numbers of Ro = 0.18, 0.19 and 0.23 respectively. For each of the turbine rotational frequencies, film cooling effectiveness is determined for average film-hole blowing ratios of Mholes = 0.5, 0.75, 1.0, 1.25, 1.5 and 2.0. To provide a complete picture of hub cooling under rotating conditions, simultaneous injection of coolant gas through upstream stator-rotor purge gap and downstream discrete film-hole is also studied. The combined tests are conducted for gap purge flow corresponding to coolant to mainstream mass flow ratio of MFR = 1% with three downstream film-hole blowing ratios of Mholes = 0.75, 1.0 and 1.25 for each of the three turbine speeds. The results for combined upstream stator-rotor gap purge flow and downstream discrete holes provide information about the optimum purge flow coolant mass, average coolant hole blowing ratios for each rotational speed and coolant injection location along the passage to obtain efficient platform film cooling.

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