Blade-Row Interaction in a High-Pressure Turbine

The influence of hot-streak magnitude and alignment relative to the vane leading edge on blade row heat flux is investigated for a one and one-half stage high-pressure turbine with a film-cooled vane, purge cooling, and uncooled blades. The full-stage turbine is operated at design-corrected conditions. In addition to investigating the impact of different hot-streak characteristics, this study also looks at the interaction of cooling flow with the hot streaks. This paper builds on the investigation of profile migration utilizing temperature measurements presented in Part I and the heat transfer measurements presented in Part II. Hot streaks aligned with the vane midpitch have a greater impact on blade temperatures and heat-flux values than hot streaks aligned with the vane leading edge. The leading edge hot streaks tend to be mixed out over the surface of the vane. The magnitude of the hot streak is observed to have the largest influence on the temperature and heat flux for the downstream blade. Time-accurate measurements confirm these conclusions and indicate that further analysis of the time-accurate data is warranted. Film cooling is found to impact a hot-streak profile in a way similar to that observed for a radial profile. Differences in core to coolant temperature ratio cause the uniform profile to show different coolant effects, but the overall spread of the cooling appears similar.

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Unsteady Simulation of a Two-Stage Cooled High Pressure Turbine Using an Efficient Non-Linear Harmonic Balance Method

Volume 6C: Turbomachinery ◽

10.1115/gt2013-94574 ◽

2013 ◽

Cited By ~ 5

Author(s):

Venkataramanan Subramanian ◽

Chad H. Custer ◽

Jonathan M. Weiss ◽

Kenneth C. Hall

Keyword(s):

High Pressure ◽

Harmonic Balance ◽

Nearest Neighbor ◽

Harmonic Balance Method ◽

Balance Method ◽

High Pressure Turbine ◽

Two Stage ◽

Nearest Neighbor Algorithm ◽

Blade Row ◽

Unsteady Simulation

The harmonic balance method is a mixed time domain and frequency domain approach for efficiently solving periodic unsteady flows. The implementation described in this paper is designed to efficiently handle the multiple frequencies that arise within a multistage turbomachine due to differing blade counts in each blade row. We present two alternative algorithms that can be used to determine which unique set of frequencies to consider in each blade row. The first, an all blade row algorithm, retains the complete set of frequencies produced by a given blade row’s interaction with all other blade rows. The second, a nearest neighbor algorithm, retains only the dominant frequencies in a given blade row that arise from direct interaction with the adjacent rows. A comparison of results from a multiple blade row simulation based on these two approaches is presented. We will demonstrate that unsteady blade row interactions are accurately captured with the reduced frequency set of the nearest neighbor algorithm, and at a lower computational cost compared to the all blade row algorithm. An unsteady simulation of a two-stage, cooled, high pressure turbine cascade is achieved using the present harmonic balance method and the nearest neighbor algorithm. The unsteady results obtained are compared to steady simulation results to demonstrate the value of performing an unsteady analysis. Considering an unsteady flow through a single blade row turbine blade passage, it is further shown that unsteady effects are important even if the objective is to obtain accurate time-averaged integrated values, such as efficiency.

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Air Model Tests of Labyrinth Seal Forces on a Whirling Rotor

Journal of Engineering for Power ◽

10.1115/1.3446390 ◽

1978 ◽

Vol 100 (4) ◽

pp. 533-543 ◽

Cited By ~ 4

Author(s):

D. V. Wright

Keyword(s):

High Pressure ◽

Labyrinth Seal ◽

Model Tests ◽

Test Results ◽

High Pressure Turbine ◽

System Parameters ◽

Valid Method ◽

Radial Stiffness ◽

Blade Row ◽

Model Rotor

Steam-excited whirl of high pressure turbine rotors is caused by shroud and shaft labyrinth seal forces and by flow forces on the blades. Accurate test results are needed to guide development of a valid method for calculating labyrinth seal whirl forces and to verify the method. This paper describes apparatus for accurate measurement of labyrinth seal forces on a whirling model rotor. The effects of some system parameters on the whirl excitation constant (whirl force/whirl amplitude.) and radial stiffness of a model seal are shown. The seal whirl force is destabilizing for some conditions and stabilizing for others. A method is given for predicting the net seal and blade-row excitation constant that will cause self-excited whirl of rotors having specified shaft and bearing parameters.

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A Parametric Study of the Blade Row Interaction in a High Pressure Turbine Stage

Journal of Turbomachinery ◽

10.1115/1.2987236 ◽

2009 ◽

Vol 131 (3) ◽

Cited By ~ 11

Author(s):

G. Persico ◽

P. Gaetani ◽

C. Osnaghi

Keyword(s):

High Pressure ◽

Strong Dependence ◽

Three Dimensional ◽

Secondary Flows ◽

Pressure Probe ◽

Turbine Stage ◽

Mixing Rate ◽

Aerodynamic Pressure ◽

Blade Row ◽

Blade Row Interaction

An extensive experimental analysis on the subject of the unsteady periodic flow in a high subsonic high pressure (HP) turbine stage has been carried out at the Laboratorio di Fluidodinamica delle Macchine of the Politecnico di Milano (Italy). In this paper the aerodynamic blade row interaction in HP turbines, enforced by increasing the stator and rotor blade loading and by reducing the stator-rotor axial gap, is studied in detail. The time-averaged three-dimensional flowfield in the stator-rotor gap was investigated by means of a conventional five-hole probe for the nominal (0 deg) and highly positive (+22 deg) stator incidences. The evolution of the viscous flow structures downstream of the stator is presented to characterize the rotor incoming flow. The blade row interaction was evaluated on the basis of unsteady aerodynamic measurements at the rotor exit, performed with a fast-response aerodynamic pressure probe. Results show a strong dependence of the time-averaged and phase-resolved flowfield and of the stage performance on the stator incidence. The structure of the vortex-blade interaction changes significantly as the magnitude of the rotor-inlet vortices increases, and very different residual traces of the stator secondary flows are found downstream of the rotor. On the contrary, the increase in rotor loading enhances the unsteadiness in the rotor secondary flows but has a little effect on the vortex-vortex interaction. For the large axial gap, a reduction of stator-related effects at the rotor exit is encountered when the stator incidence is increased as a result of the different mixing rate within the cascade gap.

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Investigation of Turbine Shroud Distortions on the Aerodynamics of a One and One-Half Stage High-Pressure Turbine

Volume 7: Turbomachinery, Parts A and B ◽

10.1115/gt2009-59562 ◽

2009 ◽

Cited By ~ 4

Author(s):

Eric A. Crosh ◽

Charles W. Haldeman ◽

Michael G. Dunn ◽

D. Graham Holmes ◽

Brian E. Mitchell

Keyword(s):

High Pressure ◽

Surface Pressure ◽

Turbo Code ◽

Traditional Approach ◽

Single Frequency ◽

Pressure Measurements ◽

Pressure Loading ◽

High Pressure Turbine ◽

Unsteady Pressure ◽

Blade Row

As part of a proactive effort to investigate the ability of computational fluid dynamic (CFD) tools to predict time-accurate surface-pressure histories, a combined experimental/computational investigation was performed examining the effect of rotor shroud (casing) out-of-roundness on the unsteady pressure loading for the blade row of a full-stage turbine. The casing out-of-roundness was idealized by designing a casing ring with a sinusoidal variation. This casing ring was used to replace a flat casing for an existing turbine and direct comparisons were made between the time-accurate pressure measurements and predictions obtained using the flat and “wavy” casings. For both casing configurations, predictions of the unsteady pressure loading for many locations on the blade and vane were obtained using Numeca’s FINE/Turbo code and the General Electric TACOMA code. This paper will concentrate on the results obtained for the “wavy” casing, but the results for the flat casing are presented as a baseline case. The time-accurate surface-pressure measurements were acquired for the vane and blade of a modern, 3-D, stage and 1/2 high-pressure turbine operating at the design corrected speed and stage pressure ratio. The research program utilized an un-cooled turbine stage for which all three airfoil rows are heavily instrumented at multiple spans to develop a full dataset. The vane-blade-vane count for this machine is 38-72-38. The number of waves in the distorted shroud “wavy wall” is approximately 1.5-times the number of vanes. The resulting changes in aerodynamic surface-pressure measurements were measurable at all blade span wise locations. Variations in time-average surface pressure of up to 5% of the flat casing values were observed. In addition, the frequency content of the time-resolved blade data for the “wavy” casing changed substantially from that measured using the flat casing, with changes in both amplitudes and frequencies. Imposing the casing irregularity changed the fundamental physics of the problem from a single frequency and its harmonics to a multi-frequency problem with mixed harmonics. The unsteady effects of this type of problem can be addressed using the harmonic method within Numeca’s FINE/Turbo code, which is designed to handle multiple blade passing frequencies and harmonics for one blade row. A more traditional approach is included in the paper by employing the TACOMA code in a linearized mode that produces results for a single frequency. These results show that casing irregularity can have a significant influence on the blade surface-pressure characteristics. Further, it is demonstrated that the FINE/Turbo code experienced difficulty predicting the unsteady pressure signal attributed to the “wavy” casing configuration, while at the same time capturing the unsteady signal attributed to the vane passing due to limitations in the current methodology.

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Investigation of Turbine Shroud Distortions on the Aerodynamics of a One and One-Half Stage High-Pressure Turbine

Journal of Turbomachinery ◽

10.1115/1.4001176 ◽

2010 ◽

Vol 133 (3) ◽

Cited By ~ 1

Author(s):

Eric A. Crosh ◽

Charles W. Haldeman ◽

Michael G. Dunn ◽

D. Graham Holmes ◽

Brian E. Mitchell

Keyword(s):

High Pressure ◽

Surface Pressure ◽

Turbo Code ◽

Single Frequency ◽

Pressure Measurements ◽

Pressure Loading ◽

High Pressure Turbine ◽

Data Set ◽

Unsteady Pressure ◽

Blade Row

As part of a proactive effort to investigate the ability of computational fluid dynamics tools to predict time-accurate surface-pressure histories, a combined experimental/computational investigation was performed, examining the effect of rotor shroud (casing) out-of-roundness on the unsteady pressure loading for the blade row of a full-stage turbine. The casing out-of-roundness was idealized by designing a casing ring with a sinusoidal variation. This casing ring was used to replace a flat casing for an existing turbine, and direct comparisons were made between the time-accurate pressure measurements and predictions obtained using the flat and “wavy” casings. For both casing configurations, predictions of the unsteady pressure loading for many locations on the blade and vane were obtained using Numeca’s FINE/TURBO code and General Electric’s turbine and compressor analysis (TACOMA) code. This paper will concentrate on the results obtained for the wavy casing, but the results for the flat casing are presented as a baseline case. The time-accurate surface-pressure measurements were acquired for the vane and blade of a modern, 3D, 1 and 1/2 stage high-pressure turbine operating at the design corrected speed and stage pressure ratio. The research program utilized an uncooled turbine stage for which all three airfoil rows are heavily instrumented at multiple spans to develop a full data set. The vane-blade-vane count for this machine is 38-72-38. The number of waves in the distorted shroud “wavy wall” is approximately 1.5 times the number of vanes. The resulting changes in the aerodynamic surface-pressure measurements were measurable at all blade spanwise locations. Variations in the time-averaged surface pressure of up to 5% of the flat casing values were observed. In addition, the frequency content of the time-resolved blade data for the wavy casing changed substantially from that measured using the flat casing, with changes in both amplitudes and frequencies. Imposing the casing irregularity changed the fundamental physics of the problem from a single frequency and its harmonics to a multifrequency problem with mixed harmonics. The unsteady effects of this type of problem can be addressed using the harmonic method within Numeca’s FINE/TURBO code, which is designed to handle multiple blade passing frequencies and harmonics for one blade row. A more traditional approach is included in this paper by employing the TACOMA code in a linearized mode that produces results for a single frequency. These results show that casing irregularity can have a significant influence on the blade surface-pressure characteristics. Further, it is demonstrated that the FINE/TURBO code experienced difficulty in predicting the unsteady pressure signal attributed to the wavy casing configuration, while at the same time, in capturing the unsteady signal attributed to the vane passing due to limitations in the current methodology.

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Aerodynamics and Heat Transfer for a Cooled One and One-Half Stage High-Pressure Turbine: Part III—Impact of Hot Streak Characteristics on Blade Row Heat Flux

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2010-23855 ◽

2010 ◽

Cited By ~ 1

Author(s):

R. M. Mathison ◽

C. W. Haldeman ◽

M. G. Dunn

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

High Pressure ◽

Radial Profile ◽

Leading Edge ◽

Coolant Temperature ◽

High Pressure Turbine ◽

Blade Row ◽

Hot Streak ◽

The Impact

The influence of hot streak magnitude and alignment relative to the vane leading edge on blade row heat flux are investigated for a one and one-half stage high-pressure turbine with a film-cooled vane, purge cooling, and un-cooled blades. The full-stage turbine is operated at design-corrected conditions. In addition to investigating the impact of different hot-streak characteristics, this study also looks at the interaction of cooling flow with the hot streaks. This paper builds on the investigation of profile migration utilizing temperature measurements presented in Part I and the heat transfer measurements presented in Part II. Hot streaks aligned with the vane mid-pitch have a greater impact on blade temperatures and heat-flux values than hot streaks aligned with the vane leading edge. The leading edge hot streaks tend to be mixed out over the surface of the vane. The magnitude of the hot streak is observed to have the largest influence on the temperature and heat flux for the downstream blade. Time-accurate measurements confirm these conclusions and indicate that further analysis of the time-accurate data is warranted. Film cooling is found to impact a hot streak profile in a way similar to that observed for a radial profile. Differences in core to coolant temperature ratio cause the uniform profile to show different coolant effects, but the overall spread of the cooling appears similar.

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Multistage Simulations of the GE90 Turbine

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/99-gt-098 ◽

1999 ◽

Cited By ~ 2

Author(s):

Mark G. Turner ◽

Paul H. Vitt ◽

David A. Topp ◽

Sohrab Saeidi ◽

Scott D. Hunter ◽

...

Keyword(s):

High Pressure ◽

Experimental Results ◽

Design Environment ◽

High Pressure Turbine ◽

Cooling Flows ◽

Low Pressure Turbine ◽

Blade Row ◽

Turbine Design ◽

First Time ◽

Good Agreement

The average passage approach has been used to analyze three multistage configurations of the GE90 turbine. These are a high pressure turbine rig, a low pressure turbine rig and a full turbine configuration comprising 18 blade rows of the GE90 engine at takeoff conditions. Cooling flows in the high pressure turbine have been simulated using source terms. This is the first time a dual-spool cooled turbine has been analyzed in 3D using a multistage approach. There is good agreement between the simulations and experimental results. Multistage and component interaction effects are also presented. The parallel efficiency of the code is excellent at 87.3% using 121 processors on an SGI Origin for the 18 blade row configuration. The accuracy and efficiency of the calculation now allow it to be effectively used in a design environment so that multistage effects can be accounted for in turbine design.

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