scholarly journals Analysis of Rotor–Stator Interaction on the Aerothermal and TBC Insulation Performance of a Turbine Stage under Hot Streak Inlet Condition

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Li Shi ◽  
Yuanfeng Lu ◽  
Hanze Huang
Keyword(s):  
Rotor Blade ◽  
Turbine Blades ◽  
Great Influence ◽  
Surface Cooling ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Rotor Stator Interaction ◽  
Hot Streak ◽  
Insulation Performance

Hot streaks and rotor–stator interaction have a great influence on the aerothermal performance of turbine blades. Previous investigations have conducted limited study of the film-cooled blade. To investigate the combined effects of a hot streak and rotor–stator interaction on the coated blade, an unsteady numerical simulation has been conducted with an efficient unsteady Navier–Stokes solver in this paper. The numerical results at four different relative stator–rotor locations (t = 0/4 T, 1/4 T, 2/4 T, and 3/4 T) have been investigated in one stator period. Compared with the stator, rotor–stator interaction exerts a significant impact on the cooling performance of the rotor blade under hot streak inlet conditions. The overall cooling effectiveness distribution of the coated rotor blade is similar to that of the uncoated blades in one stator period. Relatively lower overall cooling performance of the rotor blade can be observed in the 1/4 stator period. Then, the cooling performance begins to increase and relatively larger cooling effectiveness can be observed in the 3/4 stator period. The addition of a TBC is generally beneficial to the improvement of blade surface cooling performance, especially for the areas with low overall cooling performance. However, a negative cooling effectiveness increment can be observed at the trailing edge. It shows that for an area with poor cooling performance, the addition of thermal barrier coating will have the opposite effect. Therefore, it is necessary to enhance the design of cooling arrangements at the trailing edge to maximize the insulation performance of TBCs for the coated rotor blade.

An Experiment Study of Wall Slot Jets Pertinent to Trailing Edge Cooling of Turbine Blades

2010 ◽  
Author(s):  
Zifeng Yang ◽  
Anand Gopa Kumar ◽  
Hirofumi Igarashi ◽  
Hui Hu
Keyword(s):  
Flow Field ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Field Measurements ◽  
Main Stream ◽  
Wall Jet ◽  
Ambient Conditions ◽  
Trailing Edge ◽  
Jet Streams ◽  
Cooling Effectiveness

An experimental study was conducted to quantify the flow characteristics of wall jets pertinent to trailing edge cooling of turbine blades. A high-resolution stereoscopic PIV system was used to conduct detailed flow field measurements to quantitatively visualize the evolution of the unsteady vortex and turbulent flow structures in cooling wall jet streams and to quantify the dynamic mixing process between the cooling wall jet streams and the main stream flows. The detailed flow field measurements are correlated with the adiabatic cooling effectiveness maps measured by using pressure sensitive paint (PSP) technique to elucidate underlying physics in order to improve cooling effectiveness to protect the critical portions of turbine blades from the harsh ambient conditions.

Effect of Internal Coolant Crossflow on the Effectiveness of Shaped Film-Cooling Holes

2003 ◽  
Vol 125 (3) ◽  
pp. 547-554 ◽  
Author(s):  
Michael Gritsch ◽  
Achmed Schulz ◽  
Sigmar Wittig
Keyword(s):  
Film Cooling ◽  
Gas Flow ◽  
Flow Direction ◽  
Turbine Blades ◽  
Density Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Hot Gas ◽  
Wide Range

Film-cooling was the subject of numerous studies during the past decades. However, the effect of flow conditions on the entry side of the film-cooling hole on film-cooling performance has surprisingly not received much attention. A stagnant plenum which is widely used in experimental and numerical studies to feed the holes is not necessarily a right means to re-present real engine conditions. For this reason, the present paper reports on an experimental study investigating the effect of a coolant crossflow feeding the holes that is oriented perpendicular to the hot gas flow direction to model a flow situation that is, for instance, of common use in modern turbine blades’ cooling schemes. A comprehensive set of experiments was performed to evaluate the effect of perpendicular coolant supply direction on film-cooling effectiveness over a wide range of blowing ratios (M=0.5…2.0) and coolant crossflow Mach numbers Mac=0…0.6. The coolant-to-hot gas density ratio, however, was kept constant at 1.85 which can be assumed to be representative for typical gas turbine applications. Three different hole geometries, including a cylindrical hole as well as two holes with expanded exits, were considered. Particularly, two-dimensional distributions of local film-cooling effectiveness acquired by means of an infrared camera system were used to give detailed insight into the governing flow phenomena. The results of the present investigation show that there is a profound effect of how the coolant is supplied to the hole on the film-cooling performance in the near hole region. Therefore, crossflow at the hole entry side has be taken into account when modeling film-cooling schemes of turbine bladings.

Trailing Edge Film Cooling of Gas Turbine Airfoils: External Cooling Performance of Various Internal Pin Fin Configurations

2010 ◽  
Author(s):  
T. Horbach ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Turbine Blades ◽  
Back Surface ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Major Interest ◽  
Pin Fins ◽  
Discharge Behavior

The present paper describes an experimental study on trailing edge film cooling of modern high-pressure turbine blades using coolant ejection through planar slots on a pressure side cutback. The experimental test section consists of a generic scaled-up trailing edge model in an atmospheric open loop wind tunnel, which has been used in earlier studies by Martini et al. (e.g. [1]). An infrared thermographic measurement technique is employed, which allows for the application of engine-realistic density ratios around 1.6 by increasing the main flow temperature. The effects of different geometric configurations on the structure and performance of the cooling film are investigated in terms of film cooling effectiveness, heat transfer, and discharge behavior. Among other issues, the interaction between internal turbulators, namely an array of pin fins, with the ejection slot lip is of major interest. Therefore, different designs of the coolant ejection lip are studied. Four different ratios of lip thickness to ejection slot height (t/H = 0.2, 0.5, 1.0, 1.5) are investigated as well as three different lip profiles representing typical manufacturing imperfections and wear. Other geometric variations comprise elliptic pin fins with spanwise and streamwise orientation and the application of land extensions from the internal coolant cavity onto the cut-back surface. The blowing ratio is varied between 0.2 < M < 1.25. In terms of film cooling effectiveness the results show a strong dependency on ejection lip thickness and minor improvements are obtained with a rounded ejection lip profile. Significant improvements are achieved using land extensions. The elliptic pin fins have a strong effect on discharge behavior as well as on film cooling effectiveness and heat transfer. Except for the elliptic pin fins, the geometric variations have only a minor influence on heat transfer.

Investigation on the Effect of Different Lands on Trailing Edge Slot Film Cooling

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Yang Xu ◽  
Hui-ren Zhu ◽  
Wei-jiang Xu ◽  
Jian-sheng Wei
Keyword(s):  
Nusselt Number ◽  
Film Cooling ◽  
Turbine Blades ◽  
Experimental Studies ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Wall Functions ◽  
Film Cooling Effectiveness ◽  
Slot Film Cooling

Abstract Trailing edge slot film cooling is a widely used method for protecting the trailing edge of turbine blades from hot gas impingement. The structures that separate the slots, known as “lands,” come in a variety of configurations. This paper presents the effects of the trailing edge with different lands on the film cooling performance. Experimental studies are conducted on the film cooling effectiveness and Nusselt number with different lands. Four trailing edge configurations, including the straight lands, the beveling lands, the fillet lands and the tapered lands are considered under four blowing ratios (0.5, 0.7, 1.0 and 1.5). The Reynolds numbers of mainstream is fixed as 375,000. Film cooling effectiveness and Nusselt number performances are measured by transient liquid crystal measurement technique. Reynolds-averaged Navier-Stokes (RANS) simulation with realizable k-ε turbulence model and enhanced wall functions are performed using a commercial code Fluent. In each case, the slot height is kept constant. It is shown that the beveling lands, the fillet lands and the tapered lands have higher cooling effectiveness and lower Nusselt number compared with the straight lands. Under higher blowing ratios, the trailing edges of all four lands have higher cooling effectiveness and higher Nusselt number.

Numerical Study on the Effects of V-Shaped Rib Angle on Film Cooling Performance for Turbine Blade Trailing Edge

2018 ◽  
Author(s):  
Lin Ye ◽  
Cun-liang Liu ◽  
Hai-yong Liu ◽  
Qi-jiao He ◽  
Gang Xie
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Turbine Blade ◽  
Film Cooling ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

The trailing edge of the high-pressure turbine blade presents significant challenges to cooling structure design. To achieve better cooling performance at turbine blade trailing edge, a novel ribbed cutback structure is proposed for trailing edge cooling, which has rib structures on the cutback surface for heat transfer enhancement. In this study, numerical simulations have been performed on the effects of V-shaped rib angle on the film cooling characteristics and flow physics. Three V-shaped rib angles of 30°, 45° and 60° are studied. The distributions of adiabatic cooling effectiveness and heat transfer coefficient are obtained under blowing ratios with the value of 0.5, 1.0 and 1.5 respectively. Due to the relatively small rib height, the effect of V-shaped ribs on the film cooling effectiveness is not notable. The disadvantage of V-shaped ribs mainly exhibits at the downstream area of cutback surface. With the increase of V-shaped rib angle, the film cooling effectiveness becomes lower, but the values are still above 0.9. The V-shaped ribs obviously enhance the heat transfer on trailing edge cutback surface. The area-averaged heat transfer coefficient of the V-rib case is higher than that of the smooth case by 26.3–41.2%. The 45° V-rib case has higher heat transfer intensity than the other two V-shaped rib cases under all the three blowing ratios. However, the heat transfer coefficient distribution of the 60° V-rib case is more uniform. The heat transfer intensity of the 30° V-rib case is higher in the downstream region than the other two cases, but lower in the upstream region in which the difference becomes smaller with the increase of blowing ratio. The 45° V-rib case and the 60° V-rib case both reach the maximum value of area-averaged heat transfer intensity under blowing ratio is 1.0. Under higher blowing ratio, the 30° V-rib case and the 45° V-rib case outperform 2.1% and 6.7% higher value relative to the 60° V-rib case respectively due to the smaller velocity gradient in the 60° V-rib case in the downstream.

Numerical Investigations of Wake and Shock Wave Effects on Film Cooling Performance in a Transonic Turbine Stage: Part 1 — Methodology Development and Qualification Over Stationary Stators and Rotors

2013 ◽  
Author(s):  
Huazhao Xu ◽  
Jianhua Wang ◽  
Ting Wang
Keyword(s):  
Experimental Data ◽  
Mach Number ◽  
Film Cooling ◽  
Suction Side ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Numerical Investigations ◽  
Blowing Ratio

To understand the unsteady shock wave and wake effects on the film cooling performance over a transonic 3-D rotating stage, a series of numerical investigations have been conducted and are presented in this two-part paper. Part 1 is focused on the development of the computational model and methodology of the system setup and model qualification; Part 2 is to investigate the unsteady effects of shock waves and wakes on film cooling performance in a transonic rotating stage. In Part 1, the film cooling experimental conditions (non-rotating) and test sections of Kopper et. al. and Hunter are selected for model qualification. The numerical computation is carried out by the commercial software Ansys/Fluent using the pressure based compressible flow governing equations. The effects of four turbulence models are carefully compared with the experimental data. The Realizable k-ε turbulence model is found to match the experimental data better than the other models and is thus used for the rest of the study, including Part 2. The results show that 1) the weak shock emanating from the neighboring stator’s trailing edge results in a temperature rise and a reduction of film cooling effectiveness on the suction side near the trailing edge, 2) cooling ejection from the trailing edge reduces the shock strength in the stator passage, 3) an increase in Mach number from 0.84 to 1.50 can reduce the total pressure losses of fluid flow near the end-walls, 4) the film cooling effectiveness increases with increasing blowing ratio and becomes more even on the stator with a higher blowing ratio, and 5) an increase in Mach number from 0.84 to 1.50 gives rise to a higher cooling effectiveness in the region from the cooling holes to 80% of the chord length of the stator on the pressure side, but becomes lower after this up to the trailing edge. However, on the stator’s suction side, higher Mach number results in a lower cooling effectiveness region around the film holes from 30% to 55% of the chord length, but cooling effectiveness increases downstream.

Turbine Blade Surface Phantom Cooling From Upstream Nozzle Trailing Edge Ejection

2015 ◽  
Author(s):  
Shiou-Jiuan Li ◽  
Shang-Feng Yang ◽  
Je-Chin Han ◽  
Luzeng Zhang ◽  
Hee-Koo Moon
Keyword(s):  
Rotor Blade ◽  
Velocity Ratio ◽  
Density Ratio ◽  
Inlet Temperature ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Tip Leakage ◽  
Leakage Flows ◽  
Discharge Velocity ◽  
Tip Leakage Flows

This paper presents upstream nozzle trailing edge coolant ejection on downstream uncooled blades. Pressure sensitive paint (PSP) mass transfer technique provides detailed phantom cooling effectiveness distribution on a modeled land-based turbine rotor blade surfaces. Cavity purge and tip leakage flows are excluded, and a uniform blade inlet temperature is adopted in the current study. Experiments have completed in a low speed wind tunnel facility with a five blade linear cascade. The inlet Reynolds numbers based on chord length are 100,000 and 200,000. Nozzle trailing edge coolant ejection on rotor blade is simulated by a spoked wheel-type rotating facility with 32 hollow rods equipped with coolant ejection from 128 holes per rod. Coolant to mainstream density ratio maintains at 1.5 to match engine conditions. Nozzle coolant discharge velocity to nozzle mainstream velocity ratio varies from 0.4 to 1.4. Velocity ratios from 0.4 to 0.6 are closest to typical engine conditions. Coolant to mainstream mass flow rate ratio (MFR) is from 0.67% to 2.94%. Higher phantom cooling effectiveness occurs on suction and pressure surfaces at the velocity ratio from 0.4 to 0.6 and over 1.0, respectively. Velocity ratio effect impacts on phantom cooling effectiveness distribution more than MFR effect. Most of trailing edge coolant migrates toward blade inner and outer spans than blade mid-span. Further investigation of the trailing edge coolant ejection including cavity purge and tip leakage flows is essential for understanding real applications.

Trailing Edge Film Cooling of Gas Turbine Airfoils—External Cooling Performance of Various Internal Pin Fin Configurations

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
T. Horbach ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Turbine Blades ◽  
Open Loop ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Major Interest ◽  
Pin Fins ◽  
Discharge Behavior

The present paper describes an experimental study on trailing edge film cooling of modern high pressure turbine blades using coolant ejection through planar slots on a pressure side cutback. The experimental test section consists of a generic scaled-up trailing edge model in an atmospheric open loop wind tunnel, which has been used in several earlier studies. An infrared thermographic measurement technique is employed, which allows for the application of engine-realistic density ratios around 1.6 by increasing the main flow temperature. The effects of different geometric configurations on the structure and performance of the cooling film are investigated in terms of film cooling effectiveness, heat transfer, and discharge behavior. Among other issues, the interaction of internal turbulators, namely, an array of pin fins, with the ejection slot lip is of major interest. Therefore, different designs of the coolant ejection lip are studied. Four different ratios of lip thickness to ejection slot height (t/H=0.2,0.5,1.0,1.5), as well as three different lip profiles representing typical manufacturing imperfections and wear, are investigated. Other geometric variations comprise elliptic pin fins with spanwise and streamwise orientations and the application of land extensions from the internal coolant cavity onto the cutback surface. The blowing ratio is varied at 0.2<M<1.25. In terms of film cooling effectiveness, the results show a strong dependency on ejection lip thickness, and minor improvements are obtained with a rounded ejection lip profile. Significant improvements are achieved using land extensions. The elliptic pin fins have a strong effect on discharge behavior as well as on film cooling effectiveness and heat transfer. Except for the elliptic pin fins, the geometric variations have only a minor influence on heat transfer.

Numerical Predictions of Three-Dimensional Unsteady Turbulent Film-Cooling for Trailing Edge of Gas-Turbine Blade Using Large Eddy Simulation

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Ahmed Khalil ◽  
Hatem Kayed ◽  
Abdallah Hanafi ◽  
Medhat Nemitallah ◽  
Mohamed Habib
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Trailing Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Gas Turbine Blades ◽  
Blowing Ratio ◽  
Eddy Simulation

This work investigates the performance of film-cooling on trailing edge of gas turbine blades using unsteady three-dimensional numerical model adopting large eddy simulation (LES) turbulence scheme in a low Mach number flow regime. This study is concerned with the scaling parameters affecting effectiveness and heat transfer performance on the trailing edge, as a critical design parameter, of gas turbine blades. Simulations were performed using ANSYS-fluentworkbench 17.2. High quality mesh was adapted, whereas the size of cells adjacent to the wall was optimized carefully to sufficiently resolve the boundary layer to obtain insight predictions of the film-cooling effectiveness on a flat plate downstream the slot opening. Blowing ratio, density ratio, Reynolds number, and the turbulence intensity of the mainstream and coolant flow are optimally examined against the film-cooling effectiveness. The predicted results showed a great agreement when compared with the experiments. The results show a distinctive behavior of the cooling effectiveness with blowing ratio variation as it has a dip in vicinity of unity which is explained by the behavior of the vortex entrainment and momentum of coolant flow. The negative effect of the turbulence intensity on the cooling effectiveness is demonstrated as well.

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