Heat Transfer Measurements and Predictions for a Modern, High-Pressure, Transonic Turbine, Including Endwalls

Author(s):  
James A. Tallman ◽  
Charles W. Haldeman ◽  
Michael G. Dunn ◽  
Anil K. Tolpadi ◽  
Robert F. Bergholz

This paper presents both measurements and predictions of the hot-gas-side heat transfer to a modern, one and 1/2 stage high-pressure, transonic turbine. Comparisons of the predicted and measured heat transfer are presented for each airfoil at three locations, as well as on the various endwalls and rotor tip. The measurements were performed using the Ohio State University Gas Turbine Laboratory Test Facility (TTF). The research program utilized an uncooled turbine stage at a range of operating conditions representative of the engine: in terms of corrected speed, flow function, stage pressure ratio, and gas-to-metal temperature ratio. All three airfoils were heavily instrumented for both pressure and heat transfer measurements at multiple locations. A 3-D, compressible, Reynolds-averaged Navier-Stokes CFD solver with k-ω turbulence modeling was used for the CFD predictions. The entire, 1-1/2 stage turbine was solved using a single computation, at two different Reynolds numbers. The CFD solutions were steady, with tangentially mass-averaged inlet/exit boundary condition profiles exchanged between adjacent airfoil-rows. Overall, the CFD heat transfer predictions compared very favorably with both the global operation of the turbine and with the local measurements of heat transfer. A discussion of the features of the turbine heat transfer distributions, and their association with the corresponding flow-physics, has been included.

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
James A. Tallman ◽  
Charles W. Haldeman ◽  
Michael G. Dunn ◽  
Anil K. Tolpadi ◽  
Robert F. Bergholz

This paper presents both measurements and predictions of the hot-gas-side heat transfer to a modern, 112 stage high-pressure, transonic turbine. Comparisons of the predicted and measured heat transfer are presented for each airfoil at three locations, as well as on the various endwalls and rotor tip. The measurements were performed using the Ohio State University Gas Turbine Laboratory Test Facility (TTF). The research program utilized an uncooled turbine stage at a range of operating conditions representative of the engine: in terms of corrected speed, flow function, stage pressure ratio, and gas-to-metal temperature ratio. All three airfoils were heavily instrumented for both pressure and heat transfer measurements at multiple locations. A 3D, compressible, Reynolds-averaged Navier–Stokes computational fluid dynamics (CFD) solver with k-ω turbulence modeling was used for the CFD predictions. The entire 112 stage turbine was solved using a single computation, at two different Reynolds numbers. The CFD solutions were steady, with tangentially mass-averaged inlet/exit boundary condition profiles exchanged between adjacent airfoil-rows. Overall, the CFD heat transfer predictions compared very favorably with both the global operation of the turbine and with the local measurements of heat transfer. A discussion of the features of the turbine heat transfer distributions, and their association with the corresponding flow-physics, has been included.


Author(s):  
James A. Tallman

Computational Fluid Dynamics (CFD) was used to predict the turbine airfoil heat transfer for the high-pressure vane and high-pressure blade of a modern, one and one half stage turbine at its correct scale. Airfoil pressure and heat transfer measurements were recently obtained for the turbine in a transient shock tunnel facility, which allows for the replication of the actual engine turbine’s design corrected speed, pressure ratio, and gas-to-metal temperature ratio. A 3-D, compressible, Reynolds-averaged Navier-Stokes CFD solver with k-ω turbulence modeling was used for the CFD predictions. The turbulence model’s implementation into the numerical procedure was modified slightly, in order to better capture the model’s intended near-wall behavior and resolve the heat transfer prediction. Both the high-pressure vane and high-pressure blade were computed as steady-state flows and for two different turbine Reynolds number settings. Overall, the predictions compare very favorably with the measurement for both pressure and heat transfer at the mid-span location. A discussion of the features of the airfoil heat transfer distribution is included.


Author(s):  
Richard Celestina ◽  
Spencer Sperling ◽  
Louis Christensen ◽  
Randall Mathison ◽  
Hakan Aksoy ◽  
...  

Abstract This paper presents the development and implementation of a new generation of double-sided heat-flux gauges at The Ohio State University Gas Turbine Laboratory (GTL) along with heat transfer measurements for film-cooled airfoils in a single-stage high-pressure transonic turbine operating at design corrected conditions. Double-sided heat flux gauges are a critical part of turbine cooling studies, and the new generation improves upon the durability and stability of previous designs while also introducing high-density layouts that provide better spatial resolution. These new customizable high-density double-sided heat flux gauges allow for multiple heat transfer measurements in a small geometric area such as immediately downstream of a row of cooling holes on an airfoil. Two high-density designs are utilized: Type A consists of 9 gauges laid out within a 5 mm by 2.6 mm (0.20 inch by 0.10 inch) area on the pressure surface of an airfoil, and Type B consists of 7 gauges located at points of predicted interest on the suction surface. Both individual and high-density heat flux gauges are installed on the blades of a transonic turbine experiment for the second build of the High-Pressure Turbine Innovative Cooling program (HPTIC2). Run in a short duration facility, the single-stage high-pressure turbine operated at design-corrected conditions (matching corrected speed, flow function, and pressure ratio) with forward and aft purge flow and film-cooled blades. Gauges are placed at repeated locations across different cooling schemes in a rainbow rotor configuration. Airfoil film-cooling schemes include round, fan, and advanced shaped cooling holes in addition to uncooled airfoils. Both the pressure and suction surfaces of the airfoils are instrumented at multiple wetted distance locations and percent spans from roughly 10% to 90%. Results from these tests are presented as both time-average values and time-accurate ensemble averages in order to capture unsteady motion and heat transfer distribution created by strong secondary flows and cooling flows.


2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Harika S. Kahveci ◽  
Kevin R. Kirtley

This paper compares predictions from a 3D Reynolds-averaged Navier–Stokes code and a statistical representation of measurements from a cooled 1-1/2 stage high-pressure transonic turbine to quantify predictive process sensitivity. A multivariable regression technique was applied to both the inlet temperature measurements obtained at the inlet rake, the wall temperature, and heat transfer measurements obtained via heat-flux gauges on the blade airfoil surfaces. By using the statistically modeled temperature profiles to generate the inlet boundary conditions for the computational fluid dynamics analysis, the sensitivity of blade heat transfer predictions due to the variation in the inlet temperature profile and uncertainty in wall temperature measurements and surface roughness is calculated. All predictions are performed with and without cooling. Heat transfer predictions match reasonably well with the statistical representation of the data, both with and without cooling. Predictive precision for this study is driven primarily by inlet profile uncertainty followed by surface roughness and gauge position uncertainty.


Author(s):  
Milind A. Bakhle ◽  
Jong S. Liu ◽  
Josef Panovsky ◽  
Theo G. Keith ◽  
Oral Mehmed

Forced vibrations in turbomachinery components can cause blades to crack or fail due to high-cycle fatigue. Such forced response problems will become more pronounced in newer engines with higher pressure ratios and smaller axial gap between blade rows. An accurate numerical prediction of the unsteady aerodynamics phenomena that cause resonant forced vibrations is increasingly important to designers. Validation of the computational fluid dynamics (CFD) codes used to model the unsteady aerodynamic excitations is necessary before these codes can be used with confidence. Recently published benchmark data, including unsteady pressures and vibratory strains, for a high-pressure turbine stage makes such code validation possible. In the present work, a three dimensional, unsteady, multi blade-row, Reynolds-Averaged Navier Stokes code is applied to a turbine stage that was recently tested in a short duration test facility. Two configurations with three operating conditions corresponding to modes 2, 3, and 4 crossings on the Campbell diagram are analyzed. Unsteady pressures on the rotor surface are compared with data.


Author(s):  
Charles W. Haldeman ◽  
Michael G. Dunn ◽  
John W. Barter ◽  
Brian R. Green ◽  
Robert F. Bergholz

Aerodynamic and heat-transfer measurements were acquired using a modern stage and 1/2 high-pressure turbine operating at design corrected conditions and pressure ratio. These measurements were performed using the Ohio State University Gas Turbine Laboratory Turbine Test Facility (TTF). The research program utilized an uncooled turbine stage for which all three airfoils are heavily instrumented at multiple spans to develop a full database at different Reynolds numbers for code validation and flow-physics modeling. The pressure data, once normalized by the inlet conditions, was insensitive to the Reynolds number. The heat-flux data for the high-pressure stage suggests turbulent flow over most of the operating conditions and is Reynolds number sensitive. However, the heat-flux data does not scale according to flat plat theory for most of the airfoil surfaces. Several different predictions have been done using a variety of design and research codes. In this work, comparisons are made between industrial codes and an older code called UNSFLO-2D initially published in the late 1980’s. The comparisons show that the UNSFLO-2D results at midspan are comparable to the modern codes for the time-resolved and time-averaged pressure data, which is remarkable given the vast differences in the processing required. UNSFLO-2D models the entropy generated around the airfoil surfaces using the full Navier-Stokes equations, but propagates the entropy invisicidly downstream to the next blade row, dramatically reducing the computational power required. The accuracy of UNSFLO-2D suggests that this type of approach may be far more useful in creating time-accurate design tools, than trying to utilize full time-accurate Navier-stokes codes which are often currently used as research codes in the engine community, but have yet to be fully integrated into the design system due to their complexity and significant processor requirements.


2009 ◽  
Vol 131 (3) ◽  
Author(s):  
S. A. Southworth ◽  
M. G. Dunn ◽  
C. W. Haldeman ◽  
J.-P. Chen ◽  
G. Heitland ◽  
...  

The aerodynamics of a fully cooled axial single stage high-pressure turbine operating at design corrected conditions of corrected speed, flow function, and stage pressure ratio has been investigated. This paper focuses on flow field predictions obtained from the viewpoint of a turbine designer using the computational fluid dynamics (CFD) codes Numeca’s FINE/TURBO and the code TURBO. The predictions were all performed with only knowledge of the stage operating conditions, but without knowledge of the surface pressure measurements. Predictions were obtained with and without distributed cooling flow simulation. The FINE/TURBO model was run in 3-D viscous steady and time-accurate modes; the TURBO model was used to provide only 3-D viscous time-accurate results. Both FINE/TURBO and TURBO utilized phase-lagged boundary conditions to simplify the time-accurate model and to significantly reduce the computing time and resources. The time-accurate surface pressure loadings and steady state predictions are compared to measurements for the blade, vane, and shroud as time-averaged, time series, and power spectrum data. The measurements were obtained using The Ohio State University Gas Turbine Laboratory Turbine Test Facility. The time-average and steady comparisons of measurements and predictions are presented for 50% span on the vane and blade. Comparisons are also presented for several locations along the blade to illustrate local differences in the CFD behavior. The comparisons for the shroud are made across the blade passage at axial blade chord locations corresponding to the pressure transducer locations. The power spectrum decompositions of individual transducers (based on the fast Fourier transform (FFT)) are also included to lend insight into the unsteady nature of the flow. The comparisons show that both computational tools are capable of providing reasonable aerodynamic predictions for the vane, blade, and stationary shroud. The CFD model predictions show the encouraging trend of improved matching to the experimental data with increasing model fidelity from mass averaged to distributed cooling flow inclusion and as the codes change from steady to time-accurate modes.


1999 ◽  
Vol 121 (3) ◽  
pp. 436-447 ◽  
Author(s):  
V. Michelassi ◽  
F. Martelli ◽  
R. De´nos ◽  
T. Arts ◽  
C. H. Sieverding

A transonic turbine stage is computed by means of an unsteady Navier–Stokes solver. A two-equation turbulence model is coupled to a transition model based on integral parameters and an extra transport equation. The transonic stage is modeled in two dimensions with a variable span height for the rotor row. The analysis of the transonic turbine stage with stator trailing edge coolant ejection is carried out to compute the unsteady pressure and heat transfer distribution on the rotor blade under variable operating conditions. The stator coolant ejection allows the total pressure losses to be reduced, although no significant effects on the rotor heat transfer are found both in the computer simulation and the measurements. The results compare favorably with experiments in terms of both pressure distribution and heat transfer around the rotor blade.


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