scholarly journals On the unsteady behaviours of the adiabatic endwall film cooling effectiveness

2021 ◽  
Vol 1172 (1) ◽  
pp. 012031
Author(s):  
M Qenawy ◽  
Y Liu ◽  
W Zhou
Keyword(s):  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Endwall Film Cooling

Turbine Blade Platform Film Cooling With Simulated Swirl Purge Flow and Slashface Leakage Conditions

2016 ◽  
Author(s):  
Andrew F. Chen ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Leading Edge ◽  
Suction Side ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Purge Flow ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

The combined effects of inlet purge flow and the slashface leakage flow on the film cooling effectiveness of a turbine blade platform were studied using the pressure sensitive paint (PSP) technique. Detailed film cooling effectiveness distributions on the endwall were obtained and analyzed. The inlet purge flow was generated by a row of equally-spaced cylindrical injection holes inside a single-tooth generic stator-rotor seal. In addition to the traditional 90 degree (radial outward) injection for the inlet purge flow, injection at a 45 degree angle was adopted to create a circumferential/azimuthal velocity component toward the suction side of the blades, which created a swirl ratio (SR) of 0.6. Discrete cylindrical film cooling holes were arranged to achieve an improved coverage on the endwall. Backward injection was attempted by placing backward injection holes near the pressure side leading edge portion. Slashface leakage flow was simulated by equally-spaced cylindrical injection holes inside a slot. Experiments were done in a five-blade linear cascade with an average turbulence intensity of 10.5%. The inlet and exit Mach numbers were 0.26 and 0.43, respectively. The inlet and exit mainstream Reynolds numbers based on the axial chord length of the blade were 475,000 and 720,000, respectively. The coolant-to-mainstream mass flow ratios (MFR) were varied from 0.5%, 0.75%, to 1% for the inlet purge flow. For the endwall film cooling holes and slashface leakage flow, blowing ratios (M) of 0.5, 1.0, and 1.5 were examined. Coolant-to-mainstream density ratios (DR) that range from 1.0 (close to low temperature experiments) to 1.5 (intermediate DR) and 2.0 (close to engine conditions) were also examined. The results provide the gas turbine engine designers a better insight into improved film cooling hole configurations as well as various parametric effects on endwall film cooling when the inlet (swirl) purge flow and slashface leakage flow were incorporated.

Turbine Vane Endwall Film Cooling Effectiveness of Different Purge Slot Configurations in a Linear Cascade

2019 ◽  
Author(s):  
Gunther Müller ◽  
Christian Landfester ◽  
Martin Böhle ◽  
Robert Krewinkel
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Region Of Interest ◽  
Experimental Tests ◽  
Secondary Flows ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Vane ◽  
Density Ratios ◽  
Endwall Film Cooling

Abstract This study is concerned with the film cooling effectiveness of the flow issuing from the gap between the NGV and the transition duct on the NGV endwall, i.e. the purge slot. Different slot widths, positions and injection angles were examined in order to represent changes due to thermal expansion as well as design modifications. Apart from these geometric variations, different blowing ratios (BR) and density ratios (DR) were realized to investigate the effects of the interaction between secondary flow and film cooling effectiveness. The experimental tests were performed in a linear scale-1 cascade equipped with four highly loaded turbine vanes at the Institute of Fluid Mechanics and Fluid Machinery of the University of Kaiserslautern. The mainstream flow parameters were, with a Reynolds number of 300,000 and a Mach number (outlet) of 0.6, set to meet real engine conditions. By using various flow conditioners, periodic flow was obtained in the region of interest (ROI). The adiabatic film cooling effectiveness was determined by using the Pressure Sensitive Paint (PSP) technique. In this context, nitrogen and carbon dioxide were used as tracer gases realizing two different density ratios DR = 1.0 and 1.6. The investigation was conducted for a broad range of blowing ratios with 0.25 ≤ BR ≤ 1.50. In combination with 10 geometry variations and the aforementioned blowing and density ratio variations 100 single operating points were investigated. For a better understanding of the coolant distribution, the secondary flows on the endwall were visualized by oil dye. The measurement results will be discussed based on the areal distribution of film cooling effectiveness, its lateral spanwise as well as its area average. The results will provide a better insight into various parametric effects of gap variations on turbine vane endwall film cooling performance — notably under realistic engine conditions.

Transonic Turbine Vane Endwall Film Cooling Using PSP Measurement Technique

2019 ◽  
Author(s):  
Chao-Cheng Shiau ◽  
Izzet Sahin ◽  
Izhar Ullah ◽  
Je-Chin Han ◽  
Alexander V. Mirzamoghadam ◽  
...  
Keyword(s):  
Shock Wave ◽  
Film Cooling ◽  
Density Ratio ◽  
Cross Flow ◽  
Flow Conditions ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Turbine Vane ◽  
Endwall Film Cooling

Abstract This work focuses on the parametric study of film cooling effectiveness on turbine vane endwall under various flow conditions. The experiments were performed in a five-vane annular sector cascade facility in a blowdown wind tunnel. The controlled exit isentropic Mach numbers were 0.7, 0.9, and 1.0, from high subsonic to transonic conditions. The freestream turbulence intensity is estimated to be 12%. Three coolant-to-mainstream mass flow ratios (MFR) in the range 0.75%, 1.0%, and 1.25% are studied. N2, CO2, and Argon/SF6 mixture were used to investigate the effects of density ratio (DR), ranging from 1.0, 1.5 to 2.0. There are 8 cylindrical holes on the endwall inside the passage. Pressure-sensitive paint (PSP) technique was used to capture the endwall pressure distribution for shock wave visualization and obtain the detailed film cooling effectiveness distributions. Both the high-fidelity effectiveness contour and the laterally (spanwise) averaged effectiveness were measured to quantify the parametric effect. This study will provide the gas turbine designer more insight on how the endwall film cooling effectiveness varies with different cooling flow conditions including shock wave through the endwall cross-flow passage.

The Effects of Axisymmetric Convergent Contouring and Blowing Ratio On Endwall Film Cooling and Vane Pressure Side Surface Phantom Cooling Performance

2021 ◽  
Author(s):  
Bo Bai ◽  
Zhigang Li ◽  
Jun Li ◽  
Shuo Mao ◽  
Wing Ng
Keyword(s):  
Numerical Method ◽  
Film Cooling ◽  
Side Surface ◽  
Operating Conditions ◽  
Constant Density ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Endwall Film Cooling

Abstract In this paper, a detailed numerical investigation on the endwall film cooling and vane pressure side surface phantom cooling was performed, at the simulated realistic gas turbine operating conditions (high inlet freestream turbulence level of 16 %, exit Mach number of 0.85 and exit Reynolds number of 1.7×106). Based on a double coolant temperature model, a novel numerical method for the predictions of adiabatic wall film cooling effectiveness was proposed. This numerical method was validated by comparing the predicted results with experimental data of endwall Nusselt number, endwall film cooling effectiveness and near endwall flow visualization. The results indicate that the present numerical method can accurately predict endwall thermal load distributions and endwall film cooling distributions, and vane surface phantom cooling distributions. The endwall heat transfer coefficient, endwall film cooling effectiveness, phantom cooling effectiveness of the vane pressure side surface and total pressure loss coefficients (TPLC) were predicted and compared for two endwall contouring shapes (flat endwall and axisymmetric convergent contoured endwall) at three different blowing ratios (low blowing ratio of BR=1.0, design blowing ratio of BR=2.5 and high blowing ratio of BR=3.5) with a constant density ratio of DR=1.2, based on the present novel numerical method.

Implementation of Vortex Generator and Ramp to Improve Film Cooling Effectiveness on Blade Endwall

2021 ◽  
Author(s):  
Sadam Hussain ◽  
Xin Yan
Keyword(s):  
Numerical Methods ◽  
Film Cooling ◽  
Vortex Generator ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Baseline Case ◽  
Cooling Hole ◽  
Cooling Effects ◽  
Endwall Film Cooling

Abstract With the arrangements of vortex generators (VG) and ramp, film cooling effects on endwall near leading edge were numerically investigated at two blowing ratios (i.e. M = 0.5 and M = 1). To determine suitable numerical methods, mesh independency analysis and turbulence model selection were carried out based on the existing experimental data and LES results. With the numerical methods, flow fields near the leading edge were visualized to illustrate the influence of VG and ramp on coolant coverage on blade endwall. Film cooling effectiveness distributions on endwall and coolant trajectories near leading edge were compared among five different configurations with VG and ramp. The results show that the attachment of coolant on blade endwall is improved with the implement of VG between shaped-hole and leading edge. With the implementation of ramp on endwall between cooling hole and leading edge, the coolant spreads wider on endwall along pitchwise direction than the baseline case. With the implementation of VG and ramp, film cooling effect on endwall near leading edge is significantly improved as compared with the only ramp and only VG cases. Compared with the baseline case, pitchwise-averaged film cooling effectiveness on blade endwall near leading edge is increased by about 9%, and the film cooling effectiveness distributions on endwall along pitchwise direction become much uniform, for the case with both ramp and VG at M = 1.

Numerical investigation of blowing ratio, density ratio and axial position of film holes on the vane endwall film cooling effectiveness with upstream step

2021 ◽  
pp. 095441002110165
Author(s):  
Qingzong Xu ◽  
Qiang Du ◽  
Pei Wang ◽  
Xiangtao Xiao ◽  
Jun Liu
Keyword(s):  
Secondary Flow ◽  
Film Cooling ◽  
Pressure Loss ◽  
Total Pressure ◽  
Density Ratio ◽  
Total Pressure Loss ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Endwall Film Cooling

The aerothermal performance of interrupted slot and film holes was numerically investigated. Previous study indicates that the interrupted slot performs better compared to the conventional slot. In the meanwhile, the step formed along with the interrupted slot affects the film cooling characteristics. In this article, a row of film holes is arranged downstream of the step, and the mass flow rate for the interrupted slot is constant at 1%. Blowing ratio (BR) from 0.5 to 1.5 and density ratio from 1 to 2 were studied for the film holes. Endwall film cooling effectiveness distribution indicates that film cooling is easily affected by the secondary flow inside passage and the upstream step. Coolant traces are split into two parts due to the effects of step vortex and transverse flow. For different density ratios, increasing BR shows a different trend of film cooling effectiveness due to the variation of coolant momentum. The coolant jet is easily affected by the secondary flow when its momentum is low, but tends to liftoff when its momentum is too high. As a result, it is better to position the film holes far away from the upstream step. The total pressure loss coefficient distribution at the passage exit indicates that the coolant injection increases the total pressure loss. But density ratio has smaller effect on the loss variation. Besides, two axial positions of cooling holes were studied to improve the endwall cooling performance. Without the effect of step vortex, the film effectiveness of cooling holes is improved.

Aero-Thermal Performance of a Rotor Blade Cascade With Film Cooling in Passage Endwall

2018 ◽  
Author(s):  
Jinglun Fu ◽  
Jahed Hossain ◽  
Jayanta Kapat
Keyword(s):  
Thermal Performance ◽  
Film Cooling ◽  
Rotor Blade ◽  
Cfd Simulations ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blade Cascade ◽  
Mainstream Flow ◽  
Endwall Film Cooling ◽  
Annular Cascade

This paper describes the numerical investigations on the aerodynamic and thermal performance of a rotor blade cascade with multiple film cooling rows in the passage. First, the experimental data on an annular cascade with upstream film cooling was compared with the numerical results to validate the numerical method. The CFD simulations of the models with a row of film holes at four different locations on the hub endwall were performed respectively. The aerodynamic and thermal performance under the interaction of the secondary flow and endwall film cooling are analyzed based on the CFD predicted streamlines of mainstream flow and film injection, the contours of total pressure loss on the sections located in the passage and at the blade exit, the pitch-averaged film cooling effectiveness and film cooling effectiveness contours. The results show that film holes placed at low level of iso-Mach line tends to provide a better cooling with a smaller amount of coolant.

Turbine Vane Endwall Film Cooling Effectiveness of Different Purge Slot Configurations in a Linear Cascade

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Gunther Müller ◽  
Christian Landfester ◽  
Martin Böhle ◽  
Robert Krewinkel
Keyword(s):  
Film Cooling ◽  
Guide Vane ◽  
Density Ratio ◽  
Experimental Tests ◽  
Secondary Flows ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Turbine Vane ◽  
Density Ratios ◽  
Endwall Film Cooling

Abstract This study is concerned with the film cooling effectiveness of the flow issuing from the gap between the nozzle guide vane (NGV) and the transition duct on the NGV endwall, i.e., the purge slot. Different slot widths, positions, and injection angles were examined in order to represent changes due to thermal expansion as well as design modifications. Apart from these geometric variations, different blowing ratios (BRs) and density ratios (DRs) were realized to investigate the effects of the interaction between secondary flow and film cooling effectiveness. The experimental tests were performed in a linear scale-1 cascade equipped with four highly loaded turbine vanes at the Institute of Fluid Mechanics and Fluid Machinery of the University of Kaiserslautern. The mainstream flow parameters were, with a Reynolds number of 300,000 and a Mach number (outlet) of 0.6, set to meet real engine conditions. By using various flow conditioners, periodic flow was obtained in the region of interest (ROI). The adiabatic film cooling effectiveness was determined using the pressure sensitive paint (PSP) technique. In this context, nitrogen and carbon dioxide were used as tracer gases realizing two different density ratios DR = 1.0 and 1.6. The investigation was conducted for a broad range of blowing ratios with 0.25 ≤ BR ≤ 1.50. In combination with 10 geometry variations and the aforementioned blowing and density ratio variations, 100 single operating points were investigated. For a better understanding of the coolant distribution, the secondary flows on the endwall were visualized by oil dye. The measurement results will be discussed based on the areal distribution of film cooling effectiveness, its lateral spanwise, as well as its area average. The results will provide a better insight into various parametric effects of gap variations on turbine vane endwall film cooling performance—notably under realistic engine conditions.

Effects of Inlet Swirl on Endwall Film Cooling in Neighboring Vane Passages

2017 ◽  
Author(s):  
Yang Zhang ◽  
Yifei Li ◽  
Xiutao Bian ◽  
Xin Yuan
Keyword(s):  
Film Cooling ◽  
Rotating Flow ◽  
Leakage Flow ◽  
Cooling Effectiveness ◽  
Inlet Flow ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Inlet Swirl ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

The distribution of film cooling effectiveness of endwall film-cooling holes is considered to be periodic between neighboring high pressure turbine passages in most cascade experiments. In reality, because of the difference in the number of combustors and vanes, the flow fields of neighboring passages are completely different. The secondary flow, especially the passage vortex, is dominated by the upstream inlet rotating flow whose relative flow direction is the reverse between the neighboring vane passages. Specifying the direction of rotation to simulate inlet swirl introduces new challenges in film-cooling design. The present experiment compares five groups of endwall film-cooling with anticlockwise rotating flows at inlet at different clocking positions, and the film-cooling effect is analyzed to investigate the effects of inlet rotating flow. The inlet flow condition of neighboring passages is simulated by switching the position of a swirler fan. Hence, different rotating inlet flow conditions in different positions are achieved. The GE-E3 airfoil was used in the cascade rig, with a scaled-up factor of 1.95. The inlet Reynolds number is 1.48 × 105 and the Mach number is 0.07. The effects of the blowing ratio and relative positions of the swirler are investigated in the experiment. Adiabatic film-cooling effectiveness is probed by using pressure-sensitive paint (PSP). The coolant is simulated by nitrogen with which a density ratio of around 1.0 can be achieved. Fan-shaped film-cooling holes are introduced into the endwall surface as well as trailing edge discharge holes. The cooling performance of the combustor-turbine gap leakage flow is not considered. Fan-shaped film-cooling holes are introduced into the endwall surface as well as upstream slot. The cooling performance of the combustor-turbine gap leakage flow is considered in this case. A Pair of nozzle guide vane (NGV) passages are investigated simultaneously by which the film cooling effectiveness can be compared for the same case at the endwall surface. The inlet rotating flow is simulated by an upstream swirler, with five relative positions along the pitchwise direction. According to the experimental results, the inlet rotating flow dominates the film cooling effectiveness distribution at the endwall. The averaged film cooling effectiveness changes substantially with the change in swirler position. The rotating flow at the endwall region mainly interacts with the main flow to modify incidence angle. The influence of the inlet rotating flow is more obvious at the upstream portion. Meanwhile the downstream portion is not as sensitive to rotating flow as the upstream portion.

Sign in / Sign up

Export Citation Format

Share Document