Thermal load distributions on the large-scale turbine blade tip with a rounded inlet edge

This work presents a numerical study that was done to investigate the heat transfer characteristics of a transonic turbine blade with a scalloped shroud operating at realistic engine conditions typical of those found in a large scale, land-based gas turbine. The geometry under investigation was an infinite, linear cascade composed of the same blade and shroud design used in an experimental test rig by the research sponsor. This simulation was run for varying nominal tip clearances of 20, 80, and 5.08 mm. For each of these clearances, the simulation was run with and without the scrubbing effects of the outer casing, resulting in a total of six cases that could be used to determine the influence of tip clearance and relative casing motion on heat transfer. A high quality grid (ranging from approximately 10–12 million finite volumes depending on tip clearance) with y+ for first layer cells at or below 1.0 everywhere was used to resolve the flow down to the viscous sublayer. The “realizable” k-ε turbulence model was used for all cases. A constant wall heat flux was imposed on all the surrounding surfaces to obtain heat transfer data. Results produced include a full map of heat transfer coefficients for the suction and pressure surfaces of the blade as well as the tip, shroud, and outer casing for every case. Physical mechanisms responsible for the final heat transfer outcome for all six cases are documented.

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Detailed Heat Transfer Coefficient Distributions on a Large-Scale Gas Turbine Blade Tip

Journal of Heat Transfer ◽

10.1115/1.1373655 ◽

2000 ◽

Vol 123 (4) ◽

pp. 803-809 ◽

Cited By ~ 33

Author(s):

Shuye Teng ◽

Je-Chin Han ◽

G. M. S. Azad

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Wind Tunnel ◽

Transfer Coefficient ◽

Turbine Blade ◽

Large Scale ◽

Tip Clearance ◽

Low Speed ◽

Blade Tip ◽

Low Speed Wind Tunnel

Measurements of detailed heat transfer coefficient distributions on a turbine blade tip were performed in a large-scale, low-speed wind tunnel facility. Tests were made on a five-blade linear cascade. The low-speed wind tunnel is designed to accommodate the 107.49 deg turn of the blade cascade. The mainstream Reynolds number based on cascade exit velocity was 5.3×105. Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. The wake Strouhal number was kept at 0 or 0.1. The central blade had a variable tip gap clearance. Measurements were made at three different tip gap clearances of about 1.1 percent, 2.1 percent, and 3 percent of the blade span. Static pressure distributions were measured in the blade mid-span and on the shroud surface. Detailed heat transfer coefficient distributions were measured on the blade tip surface using a transient liquid crystal technique. Results show that reduced tip clearance leads to reduced heat transfer coefficient over the blade tip surface. Results also show that reduced tip clearance tends to weaken the unsteady wake effect on blade tip heat transfer.

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Cooling the Tip of a Turbine Blade Using Pressure Side Holes—Part I: Adiabatic Effectiveness Measurements

Journal of Turbomachinery ◽

10.1115/1.1812320 ◽

2005 ◽

Vol 127 (2) ◽

pp. 270-277 ◽

Cited By ~ 16

Author(s):

J. R. Christophel ◽

K. A. Thole ◽

F. J. Cunha

Keyword(s):

Turbine Blade ◽

Film Cooling ◽

Large Scale ◽

Engine Performance ◽

Pressure Side ◽

Transfer Coefficients ◽

Turbine Engine ◽

Flow Phenomena ◽

Blade Tip ◽

Adiabatic Effectiveness

Durability of turbine blade tips has been and continues to be challenging, particularly since increasing turbine inlet temperatures is the driver for improving turbine engine performance. As a result, cooling methods along the blade tip are crucial. Film-cooling is one typically used cooling method whereby coolant is supplied through holes placed along the pressure side of a blade. The subject of this paper is to evaluate the adiabatic effectiveness levels that occur on the blade tip through blowing coolant from holes placed near the tip of a blade along the pressure side. A range of blowing ratios was studied whereby coolant was injected from holes placed along the pressure side tip of a large-scale blade model. Also present were dirt purge holes on the blade tip, which is part of a commonly used blade design to expel any large particles present in the coolant stream. Experiments were conducted in a linear cascade with a scaled-up turbine blade whereby the Reynolds number of the engine was matched. This paper, which is Part 1 of a two part series, compares adiabatic effectiveness levels measured along a blade tip, while Part 2 combines measured heat transfer coefficients with the adiabatic effectiveness levels to assess the overall cooling benefit of pressure side blowing near a blade tip. The results show much better cooling can be achieved for a small tip gap compared with a large tip gap with different flow phenomena occurring for each tip gap setting.

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Structural Optimization Design of Large Wind Turbine Blade considering Aeroelastic Effect

Mathematical Problems in Engineering ◽

10.1155/2017/3412723 ◽

2017 ◽

Vol 2017 ◽

pp. 1-7

Author(s):

Yuqiao Zheng ◽

Yongyong Cao ◽

Chengcheng Zhang ◽

Zhe He

Keyword(s):

Structural Optimization ◽

Wind Turbine ◽

Turbine Blade ◽

Optimization Design ◽

Large Scale ◽

Wind Turbine Blade ◽

Mathematical Simulations ◽

Blade Tip ◽

And Performance ◽

Large Wind

This paper presents a structural optimization design of the realistic large scale wind turbine blade. The mathematical simulations have been compared with experimental data found in the literature. All complicated loads were applied on the blade when it was working, which impacts directly on mixed vibration of the wind rotor, tower, and other components, and this vibration can dramatically affect the service life and performance of wind turbine. The optimized mathematical model of the blade was established in the interaction between aerodynamic and structural conditions. The modal results show that the first six modes are flapwise dominant. Meanwhile, the mechanism relationship was investigated between the blade tip deformation and the load distribution. Finally, resonance cannot occur in the optimized blade, as compared to the natural frequency of the blade. It verified that the optimized model is more appropriate to describe the structure. Additionally, it provided a reference for the structural design of a large wind turbine blade.

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Transonic Passage Turbine Blade Tip Clearance With Scalloped Shroud: Part II — Losses With and Without Scrubbing Effects in Engine Configuration

Heat Transfer, Volume 2 ◽

10.1115/imece2004-59116 ◽

2004 ◽

Cited By ~ 5

Author(s):

Wayne S. Strasser ◽

Gregory M. Feldman ◽

F. Casey Wilkins ◽

James H. Leylek

Keyword(s):

Turbine Blade ◽

Turbulence Model ◽

Large Scale ◽

Pressure Ratio ◽

Viscous Sublayer ◽

Tip Clearance ◽

Tip Vortex ◽

Tip Leakage ◽

Passage Vortex ◽

Blade Tip

Loss mechanisms in a scallop shrouded transonic power generation turbine blade passage at realistic engine conditions have been identified through a series of large-scale (typically 12 million finite volumes) simulations. All simulations are run with second-order discretization and viscous sublayer resolution, and they include the effects of viscous dissipation. The mesh (y+ near unity on all surfaces) is highly refined in the tip clearance region, casing recesses, and shroud region in order to fully capture complex interdependent flow physics and the associated losses. Aerodynamic losses, in order of their relative importance, are a result of the following: separation around the tip, recesses, and shroud; tip vortex creation; downstream mixing losses, localized shocks on the airfoil; and the passage vortex emanating from under the shroud. A number of helical lateral flows were established near the upper shroud surfaces as a result of lateral pressure gradients on the scalloped shroud. It was found that the tip leakage and passage losses increased approximately linearly with increasing tip clearance, both with and without the effect of the relative casing motion. For each tip clearance studied, scrubbing slightly reduced the tip leakage, but the overall production of entropy was increased by more than 50%. Also the overall passage mass flow rate, for a given inlet total pressure to exit static pressure ratio, increased almost linearly with increasing tip clearance. In addition, it was also found that there was slight positive and negative lift on the shroud, depending on the tip clearance. At the lowest tip clearance of 20 mils there was a negative lift on the shroud. In the 200-mil tip clearance case there was a positive lift on the shroud. The relative motion of the casing contributed positively to the lift at every tip clearance, affecting more at the lowest tip clearance where the casing is closest to the blade tip. Lastly, it was found that the computed entropy generation for the stationary 80-mils case using the SKE turbulence model was close to that of the 80-mils scrubbing case using the RKE turbulence model. In light of the proposed mechanisms and their relative contributions, suggested design considerations are posed.

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Wind Turbine Blade Flow and Noise Prediction by Large-Scale LES (2nd Report, On Aerodynamic Noise Reduction of the Wind Turbine Blade Tip)

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B ◽

10.1299/kikaib.71.184 ◽

2005 ◽

Vol 71 (701) ◽

pp. 184-190 ◽

Cited By ~ 1

Author(s):

Oliver FLEIG ◽

Makoto IIDA ◽

Chuichi ARAKAWA

Keyword(s):

Wind Turbine ◽

Noise Reduction ◽

Turbine Blade ◽

Large Scale ◽

Wind Turbine Blade ◽

Aerodynamic Noise ◽

Noise Prediction ◽

Blade Tip

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Turbine Blade Tip and Casing Phantom Cooling from Blade-Surface Film Coolant

Journal of Thermophysics and Heat Transfer ◽

10.2514/1.t6093 ◽

2020 ◽

pp. 1-15

Author(s):

Feng Li ◽

Zhao Liu ◽

Zhenping Feng

Keyword(s):

Turbine Blade ◽

Surface Film ◽

Blade Surface ◽

Blade Tip

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Heat Transfer in Rotating Serpentine Passages With Trips Normal to the Flow

Journal of Turbomachinery ◽

10.1115/1.2928038 ◽

1992 ◽

Vol 114 (4) ◽

pp. 847-857 ◽

Cited By ~ 124

Author(s):

J. H. Wagner ◽

B. V. Johnson ◽

R. A. Graziani ◽

F. C. Yeh

Keyword(s):

Heat Transfer ◽

Turbine Blade ◽

Large Scale ◽

Flow Direction ◽

Operating Conditions ◽

Transfer Model ◽

Transfer Coefficients ◽

Flow Equations ◽

Turbine Blade Cooling ◽

Heat Transfer Coefficients

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges that are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat transfer increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction.

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