Transonic Vane Film Cooling with Crescent-shaped Crater using an Endoscopic Pressure-Sensitive Paint Technique

2022 ◽  
pp. 118081
Author(s):  
Kechen Wang ◽  
Hongyi Shao ◽  
Di Peng ◽  
Yingzheng Liu ◽  
Wenwu Zhou
Keyword(s):  
Film Cooling ◽  
Pressure Sensitive Paint ◽  
Pressure Sensitive

Upstream Film Cooling on the Contoured Endwall of a Transonic Turbine Vane in an Annular Cascade

2020 ◽  
Author(s):  
Daniel A. Salinas ◽  
Izhar Ullah ◽  
Lesley M. Wright ◽  
Je-Chin Han ◽  
John W. McClintic ◽  
...  
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Lateral Spread ◽  
Pressure Sensitive Paint ◽  
Blow Down ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Mainstream Flow ◽  
Additional Protection ◽  
Annular Cascade

Abstract The effects of mainstream flow velocity, density ratio (DR), and coolant-to-mainstream mass flow ratio (MFR) were investigated on a vane endwall in a transonic, annular cascade. A blow down facility consisting of five vanes was used. The film cooling effectiveness was measured using binary pressure sensitive paint (BPSP). The mainstream flow was set using isentropic exit Mach numbers of 0.7 and 0.9. The coolant-to-mainstream density ratio varied from 1.0 to 2.0. The coolant to mainstream MFR varied from 0.75% to 1.25%. The endwall was cooled by eighteen discrete holes located upstream of the vane passage to provide cooling to the upstream half of the endwall. Due to the curvature of the vane endwall, the upstream holes provided uniform coverage entering the endwall passage. The coverage was effective leading to the throat of the passage, where the downstream holes could provide additional protection. Increasing the coolant flowrate increased the effectiveness provided by the film cooling holes. Increasing the density of the coolant increases the effectiveness on the endwall while enhancing the lateral spread of the coolant. Finally, increasing the velocity of the mainstream while holding the MFR constant also yields increased protection on the endwall. Over the range of flow conditions considered in this study, the binary pressure sensitive paint proved to be a valuable tool for obtaining detailed pressure and film effectiveness distributions.

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.

Influence of Coolant Density on Turbine Blade Film Cooling at Transonic Cascade Flow Conditions Using the Pressure Sensitive Paint Technique

2021 ◽  
Author(s):  
Izhar Ullah ◽  
Sulaiman M. Alsaleem ◽  
Lesley M. Wright ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Pressure Side ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Blade Tip ◽  
Film Cooling Holes

Abstract This work is an experimental study of film cooling effectiveness on a blade tip in a stationary, linear cascade. The cascade is mounted in a blowdown facility with controlled inlet and exit Mach numbers of 0.29 and 0.75, respectively. The free stream turbulence intensity is measured to be 13.5 % upstream of the blade’s leading edge. A flat tip design is studied, having a tip gap of 1.6%. The blade tip is designed to have 15 shaped film cooling holes along the near-tip pressure side (PS) surface. Fifteen vertical film cooling holes are placed on the tip near the pressure side. The cooling holes are divided into a 2-zone plenum to locally maintain the desired blowing ratios based on the external pressure field. Two coolant injection scenarios are considered by injecting coolant through the tip holes only and both tip and PS surface holes together. The blowing ratio (M) and density ratio (DR) effects are studied by testing at blowing ratios of 0.5, 1.0, and 1.5 and three density ratios of 1.0, 1.5, and 2.0. Three different foreign gases are used to create density ratio effect. Over-tip flow leakage is also studied by measuring the static pressure distributions on the blade tip using the pressure sensitive paint (PSP) measurement technique. In addition, detailed film cooling effectiveness is acquired to quantify the parametric effect of blowing ratio and density ratio on a plane tip design. Increasing the blowing ratio and density ratio resulted in increased film cooling effectiveness at all injection scenarios. Injecting coolant on the PS and the tip surface also resulted in reduced leakage over the tip. The conclusions from this study will provide the gas turbine designer with additional insight on controlling different parameters and strategically placing the holes during the design process.

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.

Film Cooling Effectiveness on the Leading Edge Region of a Rotating Turbine Blade With Two Rows of Film Cooling Holes Using Pressure Sensitive Paint

2006 ◽  
Vol 128 (9) ◽  
pp. 879-888 ◽  
Author(s):  
Jaeyong Ahn ◽  
M. T. Schobeiri ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Rotational Speed ◽  
Film Cooling ◽  
Rotor Blade ◽  
Incidence Angle ◽  
Leading Edge ◽  
Edge Region ◽  
Pressure Sensitive Paint ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive

Detailed film cooling effectiveness distributions are measured on the leading edge of a rotating gas turbine blade with two rows (pressure-side row and suction-side row from the stagnation line) of holes aligned to the radial axis using the pressure sensitive paint (PSP) technique. Film cooling effectiveness distributions are obtained by comparing the difference of the measured oxygen concentration distributions with air and nitrogen as film cooling gas respectively and by applying the mass transfer analogy. Measurements are conducted on the first-stage rotor blade of a three-stage axial turbine at 2400rpm (positive off-design), 2550rpm (design), and 3000rpm (negative off-design), respectively. The effect of three blowing ratios is also studied. The blade Reynolds number based on the axial chord length and the exit velocity is 200,000 and the total to exit pressure ratio was 1.12 for the first-stage rotor blade. The corresponding rotor blade inlet and outlet Mach numbers are 0.1 and 0.3, respectively. The film cooling effectiveness distributions are presented along with discussions on the influence of rotational speed (off design incidence angle), blowing ratio, and upstream nozzle wakes around the leading edge region. Results show that rotation has a significant impact on the leading edge film cooling distributions with the average film cooling effectiveness in the leading edge region decreasing with an increase in the rotational speed (negative incidence angle).

Experimental Study of Effusion Cooling With Pressure-Sensitive Paint

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Guanghua Wang ◽  
Gustavo Ledezma ◽  
James DeLancey ◽  
Anquan Wang
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Cfd Simulation ◽  
Density Ratio ◽  
Open Loop ◽  
Pressure Sensitive Paint ◽  
Gas Temperature ◽  
Eddy Simulation ◽  
Pressure Sensitive ◽  
The Impact

Gas turbines overall efficiency enhancement requires further increasing of the firing temperature and decreasing of cooling flow usage. Multihole (or effusion, or full-coverage) film cooling is widely used for hot gas path components cooling in modern gas turbines. The present study focused on the adiabatic film effectiveness measurement of a round multihole flat-plate coupon. The measurements were conducted in a subsonic open-loop wind tunnel with a generic setup to cover different running conditions. The test conditions were characterized by a constant main flow Mach number of 0.1 with constant gas temperature. Adiabatic film effectiveness was measured by pressure-sensitive paint (PSP) through mass transfer analogy. CO2 was used as the coolant to reach the density ratio of 1.5. Rig computational fluid dynamics (CFD) simulation was conducted to evaluate the impact of inlet boundary layer on testing. Experimental data cover blowing ratios (BRs) at 0.4, 0.6, 0.8, 1.0, and 2.0. Both 2D maps and lateral average profiles clearly indicated that the film effectiveness increases with increasing BR for BR < 0.8 and decreases with increasing BR for BR > 0.8. This observation agreed with coolant jet behavior of single film row, i.e., attached, detached then reattached, and fully detached. PSP data quality was then discussed in detail for validating large eddy simulation.

Film-Cooling Effectiveness on a Gas Turbine Blade Tip Using Pressure-Sensitive Paint

2005 ◽  
Vol 127 (5) ◽  
pp. 521-530 ◽  
Author(s):  
Jaeyong Ahn ◽  
Shantanu Mhetras ◽  
Je-Chin Han
Keyword(s):  
Oxygen Concentration ◽  
Film Cooling ◽  
Pressure Sensitive Paint ◽  
Nitrogen Gas ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Pressure Sensitive ◽  
Blade Tip ◽  
Film Cooling Holes

Effects of the presence of squealer, the locations of the film-cooling holes, and the tip-gap clearance on the film-cooling effectiveness were studied and compared to those for a plane (flat) tip. The film-cooling effectiveness distributions were measured on the blade tip using the pressure-sensitive paint technique. Air and nitrogen gas were used as the film-cooling gases, and the oxygen concentration distribution for each case was measured. The film-cooling effectiveness information was obtained from the difference of the oxygen concentration between air and nitrogen gas cases by applying the mass transfer analogy. Plane tip and squealer tip blades were used while the film-cooling holes were located (a) along the camber line on the tip or (b) along the tip of the pressure side. The average blowing ratio of the cooling gas was 0.5, 1.0, and 2.0. Tests were conducted with a stationary, five-bladed linear cascade in a blow-down facility. The free-stream Reynolds number, based on the axial chord length and the exit velocity, was 1,138,000, and the inlet and the exit Mach numbers were 0.25 and 0.6, respectively. Turbulence intensity level at the cascade inlet was 9.7%. All measurements were made at three different tip-gap clearances of 1%, 1.5%, and 2.5% of blade span. Results show that the locations of the film-cooling holes and the presence of squealer have significant effects on surface static pressure and film-cooling effectiveness, with film-cooling effectiveness increasing with increasing blowing ratio.

scholarly journals Experimental Investigation of Rotor Tip Film Cooling at an Axial Turbine with Swirling Inflow Using Pressure Sensitive Paint

2019 ◽  
Vol 4 (3) ◽  
pp. 23 ◽  
Author(s):  
Manuel Wilhelm ◽  
Heinz-Peter Schiffer
Keyword(s):  
Film Cooling ◽  
Large Scale ◽  
Density Ratio ◽  
Pressure Sensitive Paint ◽  
Axial Turbine ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Inlet Swirl ◽  
Blade Tip ◽  
Film Cooling Holes

Rotor tip film cooling is investigated at the Large Scale Turbine Rig, which is a 1.5-stage axial turbine rig operating at low speeds. Using pressure sensitive paint, the film cooling effectiveness η at a squealer-type blade tip with cylindrical pressure-side film cooling holes is obtained. The effect of turbine inlet swirl on η is examined in comparison to an axial inflow baseline case. Coolant-to-mainstream injection ratios are varied between 0.45% and 1.74% for an engine-realistic coolant-to-mainstream density ratio of 1.5. It is shown that inlet swirl causes a reduction in η for low injection ratios by up to 26%, with the trailing edge being especially susceptible to swirl. For injection ratios greater than 0.93%, however, η is increased by up to 11% for swirling inflow, while for axial inflow a further increase in coolant injection does not transfer into a gain in η .

Unsteady Wake and Coolant Density Effects on Turbine Blade Film Cooling Using Pressure Sensitive Paint Technique

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Akhilesh P. Rallabandi ◽  
Shiou-Jiuan Li ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Pressure Sensitive Paint ◽  
Suction Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Pressure Sensitive ◽  
Unsteady Wake ◽  
Film Cooling Holes

The effect of an unsteady stator wake (simulated by wake rods mounted on a spoke-wheel wake generator) on the modeled rotor blade is studied using the pressure sensitive paint (PSP) mass-transfer analogy method. Emphasis of the current study is on the midspan region of the blade. The flow is in the low Mach number (incompressible) regime. The suction (convex) side has simple angled cylindrical film-cooling holes; the pressure (concave) side has compound angled cylindrical film-cooling holes. The blade also has radial shower-head leading edge film-cooling holes. Strouhal numbers studied range from 0 to 0.36; the exit Reynolds number based on the axial chord is 530,000. Blowing ratios range from 0.5 to 2.0 on the suction side and 0.5 to 4.0 on the pressure side. Density ratios studied range from 1.0 to 2.5, to simulate actual engine conditions. The convex suction surface experiences film-cooling jet lift-off at higher blowing ratios, resulting in low effectiveness values. The film coolant is found to reattach downstream on the concave pressure surface, increasing effectiveness at higher blowing ratios. Results show deterioration in film-cooling effectiveness due to increased local turbulence caused by the unsteady wake, especially on the suction side. Results also show a monotonic increase in film-cooling effectiveness on increasing the coolant to mainstream density ratio.

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