A numerical investigation of blade tip loadings on thick-bladed helicopter rotors

Abstract This paper describes a numerical investigation to study the effect of injecting mist (tiny water droplets) into the cooling air used to cool down rotating gas turbine blades. In this study, the conjugate heat transfer method is employed which consists of the simulation of the air/mist fluid flow inside and outside the blades as well as the heat conduction through the blade body. The complete 3-D blade with internal cooling passages and external film cooling holes on the surface and blade tip is simulated in a rotating, periodic sector of the blade. The discrete phase model (DPM) is used to simulate and track the evaporation and movement of the tiny water droplets. The rotation effect of the turbine blade is included in the CFD simulation by using the moving reference frame method. The effects of different parameters such as the mist/air ratio (10–20%) and the mist droplets size (20–40μm) on mist cooling enhancement are investigated. The results show that the mist cooling enhancements are about 10% to 25% on the outer surface of the blade and reach 50% in some locations inside the blade on the internal cooling passages walls. Most of the liquid droplets completely evaporate inside the internal cooling passages; only a limited amount of mist is able to escape from the film cooling holes to enhance the blade outer surface and blade tip cooling. The effect of 10% mist on enhanced cooling is also converted to an equivalent of a 30% reduction in cooling air flow.

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Numerical investigation of the blade tip leakage vortex cavitation in a waterjet pump

Ocean Engineering ◽

10.1016/j.oceaneng.2019.106170 ◽

2019 ◽

Vol 187 ◽

pp. 106170 ◽

Cited By ~ 10

Author(s):

Qiang Guo ◽

Xianbei Huang ◽

Baoyun Qiu

Keyword(s):

Numerical Investigation ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Blade Tip ◽

Waterjet Pump

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Numerical investigation of the vortex roll-up from a helicopter blade tip using a novel fixed-wing adaptation method

CEAS Aeronautical Journal ◽

10.1007/s13272-016-0234-z ◽

2017 ◽

Vol 8 (2) ◽

pp. 245-260 ◽

Cited By ~ 1

Author(s):

Antoine Joulain ◽

Damien Desvigne ◽

David Alfano ◽

Thomas Leweke

Keyword(s):

Numerical Investigation ◽

Helicopter Blade ◽

Blade Tip ◽

Adaptation Method

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Numerical Investigation of Counter-Rotating Open Rotor Noise Emission in Different Flight Conditions

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation ◽

10.1115/gt2012-68625 ◽

2012 ◽

Cited By ~ 5

Author(s):

Eirene Rebecca Busch ◽

Manuel Keßler ◽

Ewald Krämer

Keyword(s):

Numerical Simulations ◽

Numerical Investigation ◽

Acoustic Analysis ◽

Noise Emission ◽

Rotor Noise ◽

Total Noise ◽

Open Rotor ◽

Blade Tip

Noise emission of a 9×7 and 8×8 open rotor configuration in cruise and in take-off conditions is examined by 3D unsteady numerical simulations utilising the chimera method to represent rotor movement. The acoustic analysis has been carried out with a Ffowcs Williams-Hawkings code over one rotor revolution with a resolution of 360 time steps. To ensure covering of all sources while keeping numerical losses low different hull surfaces have been examined. The comparison of two configurations at different flight conditions shows two main noise generating effects: the single rotor emission and emission caused by interaction of the rotors. The single rotor emission can mostly be seen in the rotor plane whereas the interaction can be examined at an angle of 20 to 45 and 135 to 155 degrees to the rotating axis with approximately the same share of total noise in take-off conditions. In cruise conditions the single rotor emission prevails over the interaction. This can be explained by the transonic blade tip speeds during cruise. Due to the reduced tip speeds in take-off interaction noise contributes to the total noise with a higher share than in cruise conditions. The 8×8-configuration shows higher noise emissions by interaction since the rotor-rotor interactions occur simultaneously.

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On the Design of Horizontal Axis Two-Bladed Hinged Wind Turbines

Journal of Solar Energy Engineering ◽

10.1115/1.3267575 ◽

1984 ◽

Vol 106 (2) ◽

pp. 171-176 ◽

Cited By ~ 4

Author(s):

K. H. Hohenemser ◽

A. H. P. Swift

Keyword(s):

Angular Velocity ◽

Wind Turbines ◽

Horizontal Axis ◽

Dynamic Loads ◽

Helicopter Rotors ◽

Blade Tip ◽

Velocity Variations ◽

Large Wind

Hinged two-bladed wind turbines are not necessarily free of disturbing vibrations. The combination of elastic or built-in blade coning with blade flapping about a conventional teeter hinge produces periodic blade angular velocity variations in the blade tip path plane with associated vibrations and dynamic loads. The paper discusses and evaluates various hinge configurations for two-bladed rotors and shows why the conventional teeter hinge leads to nonuniform blade angular velocity in the blade tip path plane. The solution to this problem adopted for two-bladed helicopter rotors, though complex, could be of interest for large wind turbines. A much simpler solution, calling for the suppression of blade flapping by passive blade cyclic pitch variation produced by a strong negative pitch-flap coupling, was found to be practical for upwind tail vane stabilized two-bladed wind turbines.

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