Analysis of Hot Streak Effects on Turbine Rotor Heat Load

1997 ◽  
Vol 119 (3) ◽  
pp. 544-553 ◽  
Author(s):  
T. Shang ◽  
A. H. Epstein
Keyword(s):  
Heat Load ◽  
Three Dimensional ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Inlet Temperature ◽  
Pressure Surface ◽  
Physical Mechanisms ◽  
Design Variables ◽  
Hot Streak ◽  
Turbine Design

The influence of inlet hot streak temperature distortion on turbine blade heat load was explored on a transonic axial flow turbine stage test article using a three-dimensional, multiblade row unsteady Euler code. The turbine geometry was the same as that used for a recently reported testing of hot streak influence. Emphasis was placed on elucidating the physical mechanisms by which hot streaks affect turbine durability. It was found that temperature distortion significantly increases both blade surface heat load nonuniformity and total blade heat load by as much as 10–30 percent (mainly on the pressure surface), and that the severity of this influence is a strong function of turbine geometry and flow conditions. Three physical mechanisms were identified that drive the heat load nonuniformity: buoyancy, wake convection (the Kerrebrock–Mikolajczak effect), and Rotor–Stator interactions. The latter can generate significant nonuniformity of the time-averaged relative frame rotor inlet temperature distribution. Dependence of these effects on turbine design variables was investigated to shed light on the design space, which minimizes the adverse effects of hot streaks.

Analysis of Hot Streak Effects on Turbine Rotor Heat Load

1996 ◽  
Author(s):  
Tonghuo Shang ◽  
Alan H. Epstein
Keyword(s):  
Heat Load ◽  
Three Dimensional ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Inlet Temperature ◽  
Pressure Surface ◽  
Physical Mechanisms ◽  
Design Variables ◽  
Hot Streak ◽  
Turbine Design

The influence of inlet hot streak temperature distortion on turbine blade heat load was explored on a transonic axial flow turbine stage test article using a three-dimensional, multi-blade row unsteady Euler code. The turbine geometry was the same as that used for a recently reported testing of hot streak influence. Emphasis was placed elucidating the physical mechanisms by which hot streaks affect turbine durability. It was found that temperature distortion significantly increases both blade surface heat load nonuniformity and total blade heat load by as much as 10–30% (mainly on the pressure surface), and that the severity of this influence is a strong function of turbine geometry and flow conditions. Three physical mechanisms were identified which drive the heat load nonuniformity — buoyancy, wake convection (the Kerrebrock-Mikolajczak effect), and rotor-stator interactions. The latter can generate significant nonuniformity of the time-averaged relative frame rotor inlet temperature distribution. Dependence of these effects on turbine design variables was investigated to shed light on the design space which minimizes the adverse effects of hot streaks.

Quantitative MRI Measurements of Hot Streak Development in a Turbine Vane Cascade

2015 ◽  
Author(s):  
Sayuri D. Yapa ◽  
Christopher J. Elkins ◽  
John K. Eaton
Keyword(s):  
Film Cooling ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Quantitative Mri ◽  
Inlet Temperature ◽  
Cooling Design ◽  
Pass Through ◽  
Hot Streak

Hot streaks from the combustor and cool streaks from nozzle vane film cooling impose strong inlet temperature variations on high pressure turbine blades, which can lead to local hot or cold spots, high thermal stresses, and fatigue failures. Furthermore, the complex three dimensional flows around the vane may act to concentrate cool or hot fluid exiting the vane row. In order to optimize the cooling design of the turbine blades, the designer must be able to predict the temperature distribution entering the turbine rotor. Therefore, it is important to understand and predict how combustor hot streaks are dispersed as they pass through the vane row. The goal of the present work is to provide detailed three dimensional velocity and temperature data for simulated combustor hot streaks developing through a film cooled vane cascade using the Magnetic Resonance Velocity/Concentration experimental technique. The measurements show that the hot streaks are thinned by acceleration through the vane cascade and diffused by turbulence. The turbulent diffusivity is suppressed by acceleration and leaves significant temperature nonuniformity in the vane wake.

Study of Hot Streak Effects in a Counter-Rotating Turbine

2001 ◽  
Author(s):  
L. C. Ji ◽  
J. Z. Xu ◽  
J. Chen
Keyword(s):  
High Pressure ◽  
Heat Load ◽  
Three Dimensional ◽  
High Pressure Turbine ◽  
Design And Optimization ◽  
Low Pressure Turbine ◽  
Second Stage ◽  
Euler Solver ◽  
Hot Streak ◽  
Turbine Design

Based on its convection nature, some influences of the hot streak on a 1+1 (with inter-blade vane) counter-rotating turbine are studied by using a three-dimensional (3D) unsteady Euler solver. Emphasis is laid on the hot streak effect to the blade heat load and the clocking effects between hot streak and blade rows. One temperature distortion magnitude, two spanwise and four tangential positions, four clocking locations between vanes of first and second stage are examined. Results show that the effect of the hot streak on a counter-rotating turbine is nearly the same as a conventional turbine. However, clocking between the hot streak and the vane of the high pressure turbine (HPT) exerts significant influences on the heat load of the whole HPT stage. Also, clocking between the HPT vane and the vane of the low pressure turbine (LPT) affects the heat load of the LPT greatly. These effects cannot be captured with the steady flow assumption. So time accurate simulation about the hot streak/blade interaction must be used as a basis for the turbine design and optimization.

scholarly journals Negative Incidence Flow Over a Turbine Rotor Blade

1983 ◽  
Author(s):  
H. David Joslyn ◽  
Robert P. Dring
Keyword(s):  
Gas Turbines ◽  
Large Scale ◽  
Three Dimensional ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Surface Flow ◽  
Separated Flows ◽  
Turbine Rotor Blade ◽  
Pressure Surface ◽  
Pressure Distributions

The operation of variable cycle gas turbines at negative incidence can result in highly three dimensional separated flows on the turbine rotor pressure surface. These flows can impact both performance and durability. The present program was conducted to experimentally study the behavior of surface flow on a large scale axial flow turbine rotor with incidence varying up to and including negative incidence separation. Fullspan pressure distributions and surface flow visualization were acquired over a range of incidence. The data indicate that at large negative incidence, pressure surface separation occurred and extended to 60 percent chord at midspan. These separated flows were simulated at midspan by applying potential flow theory to match the measured pressure distributions.

Study of Hot Streak Phenomena in Subsonic and Transonic Flows

1996 ◽  
Author(s):  
Daniel J. Dorney ◽  
Douglas L. Sondak
Keyword(s):  
Shock Waves ◽  
Hot Spots ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Trailing Edge ◽  
Flow Speeds ◽  
Hot Streak ◽  
Turbine Design

Experimental data have shown that combustor hot streaks can lead to pressure side “hot spots” on first-stage turbine rotor blades. Although many modern turbines operate at high subsonic or transonic flow speeds, the majority of bot streak experiments and numerical simulations performed during the last decade have been for low-speed flows. The presence of shock waves in a turbine stage can significantly affect the surface temperature distributions, and a knowledge of the interaction between shock waves and combustor hot streaks may help in the turbine design process. In the present investigation, quasi-three-dimensional unsteady Navier-Stokes simulations have been performed for a high-pressure turbine operating at two vane settings. At the open-vane setting, the flow is predominantly high subsonic with no trailing-edge shock waves, and at the closed-vane setting there are trailing-edge shocks.

Prediction of Nonuniform Inlet Temperature Effects on Vane and Rotor Heat Transfer

1997 ◽  
Author(s):  
R. J. Boyle ◽  
P. W. Giel
Keyword(s):  
Heat Transfer ◽  
Heat Load ◽  
Three Dimensional ◽  
Tangential Direction ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Temperature Profiles ◽  
Radial Temperature ◽  
Pressure Surface ◽  
Exit Temperature

The effects of nonuniform combustor exit temperature profiles on vane and rotor heat transfer were determined using a steady-state three-dimensional Navier-Stokes analysis. Both radial and tangential nonuniform temperature profiles were individually considered. Comparisons are made with experimental data for the effects of a radial temperature nonuniformity on rotor heat transfer. There was a decrease in stator heat load, and an increase in rotor heat load for a radial temperature distribution typically seen at the combustor exit. Tangential variations in stator inlet temperature produced significant variations in stator heat load, and resulted in average rotor heat load greater than for the uniform inlet temperature case. Rotor heat load was also calculated for different stator wake locations. Accounting for the stator wake position at the rotor inlet gave a greater average rotor heat load than that obtained by averaging the stator exit flow field in the tangential direction. The increase was most notable on the rotor pressure surface.

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.

Aerodynamic Design Optimization of an Axial Flow Compressor Rotor

2002 ◽  
Author(s):  
Chan-Sol Ahn ◽  
Kwang-Yong Kim
Keyword(s):  
Design Optimization ◽  
Response Surface ◽  
Computing Time ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Navier Stokes ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Design Variables

Design optimization of a transonic compressor rotor (NASA rotor 37) using the response surface method and three-dimensional Navier-Stokes analysis has been carried out in this work. The Baldwin-Lomax turbulence model was used in the flow analysis. Three design variables were selected to optimize the stacking line of the blade. Data points for response evaluations were selected by D-optimal design, and linear programming method was used for the optimization on the response surface. As a main result of the optimization, adiabatic efficiency was successfully improved. It was found that the optimization process provides reliable design of a turbomachinery blade with reasonable computing time.

Part-Span Application of Sweep and Lean at Turbine Blade Tips: A Low Speed Experimental Cascade Study

2010 ◽  
Author(s):  
Bhaskar Roy ◽  
Anoop Prajapati
Keyword(s):  
Performance Improvement ◽  
Turbine Blade ◽  
Axial Flow ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Pressure Surface ◽  
Wall Boundary Layer ◽  
Performance Reduction ◽  
Application Potential ◽  
End Wall

This study is aimed at exploring the possibility of aerodynamic performance improvement by providing part-span forward sweep and lean near the tip regions of axial flow turbine rotor blades. Such aerodynamic benefits may have application potential in the uncooled LPT blades. The curved forward sweep and curved lean have been provided to 25% of the blade span near the tip in cascade, Three sets of cascades of the same turbine airfoil have been studied — (i) straight blades, (ii) part span swept blades and (iii) part span leaned blades. The cascade results show that swept blade gives a recovery of 20–25% loss in blade performance near the tip region at 0° and 10° incidences. The swept and leaned blades suppress the Cp perturbations (as seen in straight blades) at 0° and at 10° incidences, on the suction surfaces of turbine blade cascades. Comparatively the leaned blades show blade unloading, largely on the pressure surface, which leads to some performance reduction. The wake loss study shows reduction in wake losses for swept turbine blade at near tip region. The end-wall boundary layer measurements across the open tips demonstrate some aerodynamic improvement, near the tip regions, for parts-span swept and leaned blades.

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.

Sign in / Sign up

Export Citation Format

Share Document