Rotor Blade Heat Transfer of High Pressure Turbine Stage Under Inlet Hot-Streak and Swirl

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
A. Rahim ◽  
L. He
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Heat Load ◽  
Design Space Exploration ◽  
Role Reversal ◽  
Dominant Factor ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Lean Burn ◽  
Hot Streak

A key consideration in high pressure (HP) turbine designs is the heat load experienced by rotor blades. Impact of turbine inlet nonuniformity of combined temperature and velocity traverses, typical for a lean-burn combustor exit, has rarely been studied. For general turbine aerothermal designs, it is also of interest to understand how the behavior of lean-burn combustor traverses (with both hot-streak and swirl) might contrast with those for a rich-burn combustor (largely hot-streak only). In the present work, a computational study has been carried out on the aerothermal performance of a HP turbine stage under nonuniform temperature and velocity inlet profiles. The analyses are primarily conducted for two combined hot-streak and swirl inlets, with opposite swirl directions. In addition, comparisons are made against a hot-streak only case and a uniform inlet. The effects of three nozzle guide vane (NGV) shape configurations are investigated: straight, compound lean (CL) and reverse CL (RCL). The present results reveal a qualitative change in the roles played by heat transfer coefficient (HTC) and fluid driving (“adiabatic wall”) temperature, Taw. It has been shown that the blade heat load for a uniform inlet is dominated by HTC, whilst a hot-streak only case is largely influenced by Taw. However, in contrast to the hot-streak only case, a combined hot-streak and swirl case shows a role reversal with the HTC being a dominant factor. Additionally, it is seen that the swirling flow redistributes radially the hot fluid within the NGV passage considerably, leading to a much ‘flatter’ rotor inlet temperature profile compared to its hot-streak only counterpart. Furthermore, the rotor heat transfer characteristics for the combined traverses are shown to be strongly dependent on the NGV shaping and the inlet swirl direction, indicating a potential for further design space exploration. The present findings underline the need to clearly define relevant combustor exit temperature and velocity profiles when designing and optimizing NGVs for HP turbine aerothermal performance.

Rotor Blade Heat Transfer Characteristics for High Pressure Turbine Stage Under Inlet Temperature and Velocity Traverses

2014 ◽  
Author(s):  
A. Rahim ◽  
L. He ◽  
E. Romero
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Heat Load ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Heat Transfer Characteristics ◽  
Lean Burn ◽  
Transfer Characteristics ◽  
Hot Streak ◽  
The Impact

One of the key considerations in high pressure (HP) turbine design is the heat load experienced by rotor blades. The impact of turbine inlet non-uniformities on the blades in the form of combined temperature and velocity traverses, typical for a lean burn combustor exit, has rarely been studied. For general HP turbine aerothermal designs, it is also of interest to understand how the behavior of a lean burn combustor traverses (hot streak and swirl) might contrast with those for rich burn combustion (largely hot streak only). In the present work, a computational study has been carried out on the aerothermal performance of a HP turbine stage under non-uniform temperature and velocity inlet profiles. The analyses are primarily conducted for two combined hot streak and swirl inlets, with opposite swirl directions. In addition, comparisons are made against a hot streak only case and a uniform inlet. The effects of three NGV shape configurations are investigated; namely, straight, compound lean (CL) and reverse compound lean (RCL). The present results show that there is a qualitative change in the roles played by heat transfer coefficient (HTC) and fluid driving (‘adiabatic wall’) temperature, Taw. It has been shown that the blade heat load distribution for a uniform inlet is dominated by HTC, whilst for a hot streak only case it is wholly influenced by Taw. However, in contrast to the hot streak only case, the case with a combined hot streak and swirl shows a role reversal with the HTC being dominant in determining the heat load. Additionally, it is seen that the swirling flow radially redistributes the hot fluid within the NGV passage considerably, leading to a much ‘flatter’ rotor inlet temperature profile compared to its hot streak only counterpart. Further, the rotor heat transfer characteristics for the cases with the combined traverses are shown to be strongly dependent on the NGV shaping and the inlet swirl direction, indicating the potential for future design space exploration. The present findings underline the need to clearly define relevant combustor exit temperature and velocity profiles when designing and optimizing NGVs for HP turbine aerothermal performance.

scholarly journals Numerical Investigation on the Influence of Hot Streak Temperature Ratio in a High-Pressure Stage of Vaneless Counter-Rotating Turbine

2007 ◽  
Vol 2007 ◽  
pp. 1-14 ◽  
Author(s):  
Zhao Qingjun ◽  
Wang Huishe ◽  
Zhao Xiaolu ◽  
Xu Jianzhong
Keyword(s):  
High Pressure ◽  
Secondary Flow ◽  
Heat Load ◽  
Rotor Blades ◽  
Inlet Temperature ◽  
Combined Effects ◽  
Temperature Ratio ◽  
Flow Angle ◽  
Hot Streak ◽  
Relative Flow

The results of recent studies have shown that combustor exit temperature distortion can cause excessive heat load of high-pressure turbine (HPT) rotor blades. The heating of HPT rotor blades can lead to thermal fatigue and degrade turbine performance. In order to explore the influence of hot streak temperature ratio on the temperature distributions of HPT airfoil surface, three-dimensional multiblade row unsteady Navier-Stokes simulations have been performed in a vaneless counter-rotating turbine (VCRT). The hot streak temperature ratios from 1.0 (without hot streak) to 2.4 were used in these numerical simulations, including 1.0, 1.2, 1.6, 2.0, and 2.4 temperature ratios. The hot streak is circular in shape with a diameter equal to 25%of the span. The center of the hot streak is located at 50%of span and 0%of pitch (the leading edge of the HPT stator vane). The predicted results show that the hot streak is relatively unaffected as it migrates through the HPT stator. The hot streak mixes with the vane wake and convects towards the pressure surface (PS) of the HPT rotor when it moves over the vane surface of the HPT stator. The heat load of the HPT rotor increases with the increase of the hot streak temperature ratio. The existence of the inlet temperature distortion induces a thin layer of cooler air in the HPT rotor, which separates the PS of the HPT rotor from the hotter fluid. The numerical results also indicating the migration characteristics of the hot streak in the HPT rotor are predominated by the combined effects of secondary flow and buoyancy. The combined effects that induce the high-temperature fluid migrate towards the hub on the HPT rotor. The effect of the secondary flow on the hotter fluid increases as the hot streak temperature ratio is increased. The influence of buoyancy is directly proportional to the hot streak temperature ratio. The predicted results show that the increase of the hot streak temperature ratio trends to increase the relative Mach number at the HPT rotor outlet, and decrease the relative flow angle from 25%to 75%span at the HPT rotor outlet. In the other region of the HPT outlet, the relative flow angle increases when the hot streak temperature ratio is increased. The predicted results also indicate that the isentropic efficiency of the VCRT decreases with the increase of the hot streak temperature ratio.

scholarly journals Effect of Inlet Temperature Non-Uniformity on High-Pressure Turbine Performance

2010 ◽  
Author(s):  
Craig I. Smith ◽  
Dongil Chang ◽  
Stavros Tavoularis
Keyword(s):  
High Pressure ◽  
Heat Load ◽  
Stokes Equations ◽  
Computation Time ◽  
Radial Pressure ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
High Pressure Turbine ◽  
Navier Stokes Equations ◽  
Hot Streak

The temperature of the flow entering a high-pressure turbine stage is inherently non-uniform, as it is produced by several discrete, azimuthally-distributed combustors. In general, however, industrial simulations assume inlet temperature uniformity to simplify the preparation process and reduce computation time. The effects of a non-uniform inlet field on the performance of a commercial, transonic, single-stage, high-pressure, axial turbine with a curved inlet duct have been investigated numerically by performing URANS (Unsteady Reynolds-Averaged Navier-Stokes equations) simulations with the SST (Shear Stress Transport) turbulence model. By adjusting the alignment of the experimentally-based inlet temperature field with respect to the stator vanes, two clocking configurations were generated: an aligned case, in which each hot streak impinged on a vane and a misaligned case, in which each hot streak passed between two vanes. In the aligned configuration, the hot streaks produced higher time-averaged heat load on the vanes and lower heat load on the blades. As the aligned hot streaks impinged on the stator vanes, they also spread spanwise due to the actions of the casing passage vortices and the radial pressure gradient; this resulted in a stream entering the rotor with relatively low temperature variations. The misaligned hot streaks were convected undisturbed past the relatively cool vane section. Relatively high time-averaged enthalpy values were found to occur on the pressure side of the blades in the misaligned configuration. The non-uniformity of the time-averaged enthalpy on the blade surfaces was lower in the aligned configuration. The flow exiting the rotor section was much less non-uniform in the aligned case, but differences in calculated efficiency were not significant.

Influence of Hot Streak Circumferential Length-Scale in Transonic Turbine Stage

2004 ◽  
Author(s):  
L. He ◽  
V. Menshikova ◽  
B. R. Haller
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Guide Vane ◽  
Strong Dependence ◽  
Rotor Blades ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Blade Vibration ◽  
Nozzle Guide ◽  
Hot Streak

A computational study is carried out on the influence of turbine inlet temperature distortion (hot streak). The hot streak effects are examined from both aeromechanical (forced blade vibration) and aero-thermal (heat transfer) points of view. Computations are firstly carried out for a transonic HP turbine stage, and the steady and unsteady surface pressure results are compared with the corresponding experimental data. Subsequent analysis is carried out for hot-streaks with variable circumferential wavelength, corresponding to different numbers of combustion burners. The results show that the circumferential wavelength of the temperature distortion can significantly change unsteady forcing as well as the heat-transfer to rotor blades. In particular, when the hot-streak wavelength is the same as the nozzle guide vane (NGV) blade pitch, there is a strong dependence of the preferential heating characteristics on the relative clocking position between hot-streak and NGV blade. However, this clocking dependence is shown to be qualitatively weakened for the cases with fewer hot streaks with longer circumferential wavelengths.

Numerical Investigation on Unsteady Effects of Hot Streak on Flow and Heat Transfer in a Turbine Stage

2008 ◽  
Author(s):  
Bai-Tao An ◽  
Jian-Jun Liu ◽  
Hong-De Jiang
Keyword(s):  
Heat Transfer ◽  
Rotor Blade ◽  
Heat Load ◽  
Leading Edge ◽  
Turbine Stage ◽  
Characteristic Analysis ◽  
Flow And Heat Transfer ◽  
Total Temperature ◽  
Inlet Conditions ◽  
Hot Streak

This paper presents a detailed flow and heat transfer characteristic analysis on gas turbine first stage turbine under hot streak inlet conditions. Two kinds of inlet total temperature conditions are specified at the turbine stage inlet. The first is uniform inlet total temperature, and the second is hot streak 2D total temperature contour. The two kinds of inlet conditions have the same mass-averaged total temperature, and the same uniform inlet total pressure. The hot streak total temperature contours are obtained according to the exit shape of an annular-can combustor. The ratio of the highest total temperature in the hot streak to the mass-averaged total temperature is about 1.23, and one hot streak corresponds to two vane passages and four blade passages. Six hot streak circumferential positions relative to the vane 1 leading edge varied from −2% to 81% pitch are computed and analyzed. Results show that hot streak obviously increases the non-uniform degree of vane heat load in comparison with the uniform total temperature inlet condition. The change of hot streak circumferential position leads to the circumferential parameter variation at stator exit, and also leads to different transient periodic fluctuating characteristics of heat load and pressure on rotor blade surface. The hot streak of relative pitch at 65% obtains similar heat load for the two vanes corresponding to one hot streak and small fluctuation of the averaged heat load on rotor blade.

Heat Transfer for the Film-Cooled Vane of a 1-1/2 Stage High-Pressure Transonic Turbine—Part I: Experimental Configuration and Data Review With Inlet Temperature Profile Effects

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Harika S. Kahveci ◽  
Charles W. Haldeman ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Turbine Stage ◽  
Suction Surface ◽  
Airfoil Surface ◽  
Pressure Surface ◽  
Cooling Flow ◽  
The Impact

This paper investigates the vane airfoil and inner endwall heat transfer for a full-scale turbine stage operating at design corrected conditions under the influence of different vane inlet temperature profiles and vane cooling flow rates. The turbine stage is a modern 3D design consisting of a cooled high-pressure vane, an un-cooled high-pressure rotor, and a low-pressure vane. Inlet temperature profiles (uniform, radial, and hot streaks) are created by a passive heat exchanger and can be made circumferentially uniform to within ±5% of the bulk average inlet temperature when desired. The high-pressure vane has full cooling coverage on both the airfoil surface and the inner and outer endwalls. Two circuits supply coolant to the vane, and a third circuit supplies coolant to the rotor purge cavity. All of the cooling circuits are independently controlled. Measurements are performed using double-sided heat-flux gauges located at four spans of the vane airfoil surface and throughout the inner endwall region. Analysis of the heat transfer measured for the uncooled downstream blade row has been reported previously. Part I of this paper describes the operating conditions and data reduction techniques utilized in this analysis, including a novel application of a traditional statistical method to assign confidence limits to measurements in the absence of repeat runs. The impact of Stanton number definition is discussed while analyzing inlet temperature profile shape effects. Comparison of the present data (Build 2) to the data obtained for an uncooled vane (Build 1) clearly illustrates the impact of the cooling flow and its relative effects on both the endwall and airfoils. Measurements obtained for the cooled hardware without cooling applied agree well with the solid airfoil for the airfoil pressure surface but not for the suction surface. Differences on the suction surface are due to flow being ingested on the pressure surface and reinjected on the suction surface when coolant is not supplied for Build 2. Part II of the paper continues this discussion by describing the influence of overall cooling level variation and the influence of the vane trailing edge cooling on the vane heat transfer measurements.

Effects of Hot Streak and Airfoil Clocking on Heat Transfer and Aerodynamic Characteristics in Gas Turbine

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Zhenping Feng ◽  
Zhaofang Liu ◽  
Yan Shi ◽  
Zhiduo Wang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Gas Turbine ◽  
Heat Load ◽  
Aerodynamic Characteristics ◽  
High Heat ◽  
Inlet Temperature ◽  
Blade Surface ◽  
Heat Transfer Characteristics ◽  
Hot Streak

The effects of the hot streak and airfoil clocking on the heat transfer and aerodynamic characteristics in a high pressure (HP) gas turbine have been investigated in this paper. The blade geometry is taken from the first 1.5 stage turbine of GE-E3 engine. To study the effect of hot streak clocking, three cases under nonuniform and uniform inlet temperature boundary conditions were simulated first. Subsequently, four clocking positions (CPs) of S2 (second stator) were arranged in these three cases to study the combined effect of hot streak and airfoil clocking. By solving the unsteady compressible Reynolds-averaged Navier–Stokes (RANS) equations, time-dependent solutions for the flow and heat transfer characteristics of the 1.5 stage turbine were obtained. The results indicate that impinged by different inlet temperature profiles, the heat flux distribution on S1 (first stator) blade varies significantly. Due to the separation of hot and cold fluid, more hot fluid flows toward pressure side (PS) of R1 (first rotor) and worsens the heat transfer environment there. The high heat flux on the R1 blade surface is controlled not only by the high heat transfer coefficient but also by the large temperature difference. By adjusting the CPs of S2, the hot streak fragments from the upstream could be guided to different places in S2 passage, to reduce the heat load on S2 blade surface. In view of the influence of the heat transfer characteristics, the nonadiabatic efficiency is calculated. The combined effects of the hot streak and airfoil clocking have been discussed, and the proper matching position for the two kinds of clocking could be selected for a higher nonadiabatic efficiency and lower heat load on S2 blade and end walls.

Analysis of Radial Migration of Hot-Streak in Swirling Flow Through High-Pressure Turbine Stage

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
B. Khanal ◽  
L. He ◽  
J. Northall ◽  
P. Adami
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Swirling Flow ◽  
Guide Vane ◽  
Lean Burn ◽  
Considerable Impact ◽  
Computational Fluid Dynamics Cfd ◽  
Nozzle Guide ◽  
Hot Streak ◽  
Computational Analyses

The high pressure (HP) turbine is subject to inlet flow nonuniformities resulting from the combustor. A lean-burn combustor tends to combine temperature variations with strong swirl and, although considerable research efforts have been made to study the effects of a circumferential temperature nonuniformity (hot-streak), there is relatively little known about the interaction between the two. This paper presents a numerical investigation of the transonic test HP stage MT1 behavior under the combined influence of the swirl and hot-streak. The in house Rolls-Royce HYDRA numerical computational fluid dynamics (CFD) suite is used for all the simulations of the present study. Baseline configurations with either hot-streak or swirl at the stage inlet are analyzed to assess the methodology and to identify reference performance parameters through comparisons with the experimental data. Extensive computational analyses are then carried out for the cases with hot-streak and swirl combined, including both the effects of the combustor-nozzle guide vane (NGV) clocking and the direction of the swirl. The present results for the combined hot-streak and swirl cases reveal distinctive radial migrations of hot fluid in the NGV and rotor passages with considerable impact on the aerothermal performance. It is illustrated that the blade heat transfer characteristics and their dependence on the clocking position can be strongly affected by the swirl direction. A further computational examination is carried out on the validity of a superposition of the influences of swirl and hot-streak. It shows that the blade heat transfer in a combined swirl and hot-streak case cannot be predicted by the superposition of each in isolation.

Numerical Investigation on Unsteady Effects of Hot Streak on Flow and Heat Transfer in a Turbine Stage

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Bai-Tao An ◽  
Jian-Jun Liu ◽  
Hong-De Jiang
Keyword(s):  
Heat Transfer ◽  
Rotor Blade ◽  
Heat Load ◽  
Leading Edge ◽  
Turbine Stage ◽  
Characteristic Analysis ◽  
Flow And Heat Transfer ◽  
Total Temperature ◽  
Inlet Conditions ◽  
Hot Streak

This paper presents a detailed flow and heat transfer characteristic analysis on gas turbine first-stage turbine under hot streak inlet conditions. Two kinds of inlet total temperature conditions are specified at the turbine stage inlet. The first is uniform inlet total temperature, and the second is hot streak 2D total temperature contour. The two kinds of inlet conditions have the same mass-averaged total temperature and the same uniform inlet total pressure. The hot streak total temperature contours are obtained according to the exit shape of an annular-can combustor. The ratio of the highest total temperature in the hot streak to the mass-averaged total temperature is about 1.23, and one hot streak corresponds to two vane passages and four blade passages. Six hot streak circumferential positions relative to the Vane 1 leading edge varied from −2% to 81% pitch are computed and analyzed. The results show that hot streak obviously increases the nonuniform degree of vane heat load in comparison with the uniform total temperature inlet condition. The change in hot streak circumferential position leads to the circumferential parameter variation at stator exit and also leads to different transient periodic fluctuating characteristics of heat load and pressure on the rotor blade surface. The hot streak of relative pitch at 65% obtains a similar heat load for the two vanes corresponding to one hot streak and small fluctuation in the averaged heat load on the rotor blade.

Heat Transfer for the Film-Cooled Vane of a 1-1/2 Stage High-Pressure Transonic Turbine: Part I—Experimental Configuration and Data Review With Inlet Temperature Profile Effects

2011 ◽  
Author(s):  
Harika S. Kahveci ◽  
Charles W. Haldeman ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Turbine Stage ◽  
Suction Surface ◽  
Airfoil Surface ◽  
Pressure Surface ◽  
Cooling Flow ◽  
The Impact

This paper investigates the vane airfoil and inner endwall heat transfer for a full-scale turbine stage operating at design corrected conditions under the influence of different vane inlet temperature profiles and vane cooling flow rates. The turbine stage is a modern 3-D design consisting of a cooled high-pressure vane, an un-cooled high-pressure rotor, and a low-pressure vane. Inlet temperature profiles (uniform, radial and hot streaks) are created by a passive heat exchanger and can be made circumferentially uniform to within ±5% of the bulk average inlet temperature when desired. The high-pressure vane has full cooling coverage on both the airfoil surface and the inner and outer endwalls. Two circuits supply coolant to the vane, and a third circuit supplies coolant to the rotor purge cavity. All of the cooling circuits are independently controlled. Measurements are performed using double-sided heat-flux gauges located at four spans of the vane airfoil surface and throughout the inner endwall region. Analysis of the heat transfer measured for the uncooled downstream blade row has been reported previously. Part I of this paper describes the operating conditions and data reduction techniques utilized in this analysis, including a novel application of a traditional statistical method to assign confidence limits to measurements in the absence of repeat runs. The impact of Stanton Number definition is discussed while analyzing inlet temperature profile shape effects. Comparison of the present data (Build 2) to the data obtained for an un-cooled vane (Build 1) clearly illustrates the impact of the cooling flow and its relative effects on both the endwall and airfoils. Measurements obtained for the cooled hardware without cooling applied agree well with the solid air-foil for the airfoil pressure surface but not for the suction surface. Differences on the suction surface are due to flow being ingested on the pressure surface and re-injected on the suction surface when coolant is not supplied for Build 2. Part II of the paper continues this discussion by describing the influence of overall cooling level variation and the influence of the vane trailing edge cooling on the vane heat transfer measurements.

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