G0801-1-4 Studies on Film Cooling of High Pressure Turbine Endwall with Leakage Flow

An experiment has been conducted to study stator/rotor disc cavity leakage flow on the platform of a highly loaded stationary linear blade cascade. The linear cascade consists of a scaled-up model of the high-pressure turbine blades of an E3 (Energy efficient engine) and leakage slot models installed under the platform. Experiments have been conducted to investigate the effect of the slot injection angle, leakage flow rates, distance between the leading edge of the blade and the slot, and spacing of the blades. The film-cooling effectiveness was measured by pressure sensitive paint (PSP), and the temperature fields and flow fields were investigated using laser-induced fluorescence (LIF) and particle image velocimetry (PIV), respectively. It was observed from the experiments that the leakage flow covered the surface of the blade platform when the distance between the leading edge and the slot was zero; however, with increasing distance, the horseshoe vortex dominates near the junction of the blade leading edge, and the leakage flow could not cover the region. It was also found that the leakage flow has an effect that promotes the formation of the horseshoe vortex for some experimental conditions.

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Unsteady Film Cooling Performance on the High Pressure Turbine Shroud Under Rotor-Stator Interaction for an Aero-Engine

10.1115/gt2021-58889 ◽

2021 ◽

Author(s):

Zihao Bao ◽

Zhihai Kou ◽

Bo Han ◽

Guangchao Li

Keyword(s):

High Pressure ◽

Film Cooling ◽

Leakage Flow ◽

High Pressure Turbine ◽

Cooling Performance ◽

Blade Rotation ◽

Aero Engine ◽

Rotor Stator Interaction ◽

Blade Tip ◽

Aero Engines

Abstract The turbine rotor inlet temperature of modern aero-engines has continuously increased in order to achieve higher thrust-to-weight ratio and thermal efficiency, which requires higher cooling effectiveness for turbine components. The turbine shroud is exposed to the blade tip leakage flow, and has become a common limiting factor for the turbine stage of advanced aero-engines. The three-dimensional numerical simulation on the unsteady film cooling characteristics of the high-pressure turbine shroud for an aero-engine under the rotor-stator interaction and the high blade rotation speed was conducted. The sliding grid technology was used to realize the relative movement between the turbine blade and the turbine shroud, and the rotor-stator interaction. Effects of the blade rotation, blowing ratios and the film jet direction on the unsteady film cooling performance of the high-pressure turbine shroud were revealed. It is found that the film cooling characteristics of the turbine shroud present an unsteady and periodic phenomenon. The blade tip clearance leakage flow, leakage vortex and mainstream suppression have important effects on the film cooling performance of the high-pressure turbine shroud. More attention should be paid to the insufficient cooling margin of the front row film holes due to coolant jet liftoff from the shroud surface under the high blowing ratio.

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Aerothermal Effect of Cavity Welding Beads on a Transonic Squealer Tip

Volume 7B: Heat Transfer ◽

10.1115/gt2020-14443 ◽

2020 ◽

Author(s):

Joao Vieira ◽

John Coull ◽

Peter Ireland ◽

Eduardo Romero

Keyword(s):

High Pressure ◽

Film Cooling ◽

Turbine Blades ◽

Reynolds Numbers ◽

High Pressure Turbine ◽

Cooling Effectiveness ◽

Film Cooling Effectiveness ◽

Aerodynamic Loss ◽

Blade Tip ◽

Mass Flow Rates

Abstract High pressure turbine blade tips are critical for gas turbine performance and are sensitive to small geometric variations. For this reason, it is increasingly important for experiments and simulations to consider real geometry features. One commonly absent detail is the presence of welding beads on the cavity of the blade tip, which are an inherent by-product of the blade manufacturing process. This paper therefore investigates how such welds affect the Nusselt number, film cooling effectiveness and aerodynamic performance. Measurements are performed on a linear cascade of high pressure turbine blades at engine realistic Mach and Reynolds numbers. Two cooled blade tip geometries were tested: a baseline squealer geometry without welding beads, and a case with representative welding beads added to the tip cavity. Combinations of two tip gaps and several coolant mass flow rates were analysed. Pressure sensitive paint was used to measure the adiabatic film cooling effectiveness on the tip, which is supplemented by heat transfer coefficient measurements obtained via infrared thermography. Drawing from all of this data, it is shown that the weld beads have a generally detrimental impact on thermal performance, but with local variations. Aerodynamic loss measured downstream of the cascade is shown to be largely insensitive to the weld beads.

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Heat Transfer and Aerodynamics of Over-Shroud Leakage Flows in a High-Pressure Turbine

Volume 3: Heat Transfer, Parts A and B ◽

10.1115/gt2009-59531 ◽

2009 ◽

Cited By ~ 3

Author(s):

Knut Lehmann ◽

Richard Thomas ◽

Howard Hodson ◽

Vassilis Stefanis

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Large Scale ◽

Suction Side ◽

Surface Flow ◽

Tip Clearance ◽

Flow Visualisation ◽

Leakage Flow ◽

High Pressure Turbine ◽

High Heat Transfer

An experimental study has been conducted to investigate the distribution of the convective heat transfer on the shroud of a high pressure turbine blade in a large scale rotating rig. A continuous thin heater foil technique has been adapted and implemented on the turbine shroud. Thermochromic Liquid Crystals were employed for the surface temperature measurements to derive the experimental heat transfer data. The heat transfer is presented on the shroud top surfaces and the three fins. The experiments were conducted for a variety of Reynolds numbers and flow coefficients. The effects of different inter-shroud gap sizes and reduced fin tip clearance gaps were also investigated. Details of the shroud flow field were obtained using an advanced Ammonia-Diazo surface flow visualisation technique. CFD predictions are compared with the experimental data and used to aid interpretation. Contour maps of the Nusselt number reveal that regions of highest heat transfer are mostly confined to the suction side of the shroud. Peak values exceed the average by as much as 100 percent. It has been found that the interaction between leakage flow through the inter-shroud gaps and the fin tip leakage jets are responsible for this high heat transfer. The inter-shroud gap leakage flow causes a disruption of the boundary layer on the turbine shroud. Furthermore, the development of the large recirculating shroud cavity vortices is severely altered by this leakage flow.

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Investigation of High-Pressure Turbine Endwall Film-Cooling Performance Under Realistic Inlet Conditions

Journal of Propulsion and Power ◽

10.2514/1.b34365 ◽

2012 ◽

Vol 28 (4) ◽

pp. 799-810 ◽

Cited By ~ 8

Author(s):

Simone Salvadori ◽

Luca Ottanelli ◽

Magnus Jonsson ◽

Peter Ott ◽

Francesco Martelli

Keyword(s):

High Pressure ◽

Film Cooling ◽

High Pressure Turbine ◽

Cooling Performance ◽

Inlet Conditions ◽

Endwall Film Cooling

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Time-Averaged and Time-Accurate Aerodynamic Effects of Forward Rotor Cavity Purge Flow for a High-Pressure Turbine: Part I—Analytical and Experimental Comparisons

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2012-69937 ◽

2012 ◽

Cited By ~ 1

Author(s):

Brian R. Green ◽

Randall M. Mathison ◽

Michael G. Dunn

Keyword(s):

High Pressure ◽

Flow Field ◽

Film Cooling ◽

Pressure Ratio ◽

Three Dimensional ◽

Unsteady Aerodynamics ◽

Flow Path ◽

Field Analysis ◽

High Pressure Turbine ◽

Purge Flow

The effect of rotor purge flow on the unsteady aerodynamics of a high-pressure turbine stage operating at design corrected conditions has been investigated both experimentally and computationally. The experimental configuration consisted of a single-stage high-pressure turbine with a modern film-cooling configuration on the vane airfoil as well as the inner and outer end-wall surfaces. Purge flow was introduced into the cavity located between the high-pressure vane and the high-pressure disk. The high-pressure blades and the downstream low-pressure turbine nozzle row were not cooled. All hardware featured an aerodynamic design typical of a commercial high-pressure ratio turbine, and the flow path geometry was representative of the actual engine hardware. In addition to instrumentation in the main flow path, the stationary and rotating seals of the purge flow cavity were instrumented with high frequency response, flush-mounted pressure transducers and miniature thermocouples to measure flow field parameters above and below the angel wing. Predictions of the time-dependent flow field in the turbine flow path were obtained using FINE/Turbo, a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code that had the capability to perform both steady and unsteady analysis. The steady and unsteady flow fields throughout the turbine were predicted using a three blade-row computational model that incorporated the purge flow cavity between the high-pressure vane and disk. The predictions were performed in an effort to mimic the design process with no adjustment of boundary conditions to better match the experimental data. The time-accurate predictions were generated using the harmonic method. Part I of this paper concentrates on the comparison of the time-averaged and time-accurate predictions with measurements in and around the purge flow cavity. The degree of agreement between the measured and predicted parameters is described in detail, providing confidence in the predictions for flow field analysis that will be provided in Part II.

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The Influence of Purge Flow Parameters on Heat Transfer and Film Cooling in Turbine Center Frames

10.1115/gt2021-59496 ◽

2021 ◽

Author(s):

Patrick R. Jagerhofer ◽

Marios Patinios ◽

Tobias Glasenapp ◽

Emil Göttlich ◽

Federica Farisco

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Film Cooling ◽

Convective Heat Transfer Coefficient ◽

Density Ratio ◽

Constant Heat Flux ◽

High Pressure Turbine ◽

Film Cooling Effectiveness ◽

Blowing Ratio ◽

Purge Flow

Abstract Due to stringent environmental legislation and increasing fuel costs, the efficiencies of modern turbofan engines have to be further improved. Commonly, this is facilitated by increasing the turbine inlet temperatures in excess of the melting point of the turbine components. This trend has reached a point where not only the high-pressure turbine has to be adequately cooled, but also components further downstream in the engine. Such a component is the turbine center frame (TCF), having a complex aerodynamic flow field that is also highly influenced by purge-mainstream interactions. The purge air, being injected through the wheelspace cavities of the upstream high-pressure turbine, bears a significant cooling potential for the TCF. Despite this, fundamental knowledge of the influencing parameters on heat transfer and film cooling in the TCF is still missing. This paper examines the influence of purge-to-mainstream blowing ratio, purge-to-mainstream density ratio and purge flow swirl angle on the convective heat transfer coefficient and the film cooling effectiveness in the TCF. The experiments are conducted in a sector-cascade test rig specifically designed for such heat transfer studies using infrared thermography and tailor-made flexible heating foils with constant heat flux. The inlet flow is characterized by radially traversing a five-hole-probe. Three purge-to-mainstream blowing ratios and an additional no purge case are investigated. The purge flow is injected without swirl and also with engine-similar swirl angles. The purge swirl and blowing ratio significantly impact the magnitude and the spread of film cooling in the TCF. Increasing blowing ratios lead to an intensification of heat transfer. By cooling the purge flow, a moderate variation in purge-to-mainstream density ratio is investigated, and the influence is found to be negligible.

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THE INFLUENCE OF PURGE FLOW PARAMETERS ON HEAT TRANSFER AND FILM COOLING IN TURBINE CENTER FRAMES

Journal of Turbomachinery ◽

10.1115/1.4053235 ◽

2021 ◽

pp. 1-26

Author(s):

Patrick René Jagerhofer ◽

Marios Patinios ◽

Tobias Glasenapp ◽

Emil Goettlich ◽

Federica Farisco

Keyword(s):

Heat Transfer ◽

High Pressure ◽

Film Cooling ◽

Density Ratio ◽

Constant Heat Flux ◽

Inlet Temperature ◽

High Pressure Turbine ◽

Turbofan Engines ◽

Blowing Ratio ◽

Purge Flow

Abstract The imperative improvement in the efficiency of turbofan engines is commonly facilitated by increasing the turbine inlet temperature. This development has reached a point where also components downstream of the high-pressure turbine have to be adequately cooled. Such a component is the turbine center frame (TCF), known for a complex aerodynamic flow highly influenced by purge-mainstream interactions. The purge air, being injected through the wheelspace cavities of the upstream high-pressure turbine, bears a significant cooling potential for the TCF. Despite this, fundamental knowledge of the influencing parameters on heat transfer and film cooling in the TCF is still missing. This paper examines the influence of purge-to-mainstream blowing ratio, density ratio and purge swirl angle on heat transfer and film cooling in the TCF. The experiments are conducted in a sector-cascade test rig specifically designed for such heat transfer studies using infrared thermography and tailor-made flexible heating foils with constant heat flux. Three purge-to-mainstream blowing ratios and an additional no purge case are investigated. The purge flow is injected without swirl and also with engine-similar swirl angles. The purge swirl and blowing ratio significantly impact the magnitude and the spread of film cooling in the TCF. Increasing blowing ratios lead to an intensification of heat transfer. By cooling the purge flow, a moderate variation in purge-to-mainstream density ratio is investigated, and the influence is found to be negligible.

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