Thermal Stress Relief Effect of Surface Roughness for Robust Thin Film Sensors Embedded on Turbine Blade Surface

1997 ◽

Cited By ~ 1

Author(s):

Roger W. Moss ◽

Roger W. Ainsworth ◽

Tom Garside

Keyword(s):

Thin Film ◽

Heat Transfer ◽

Experimental Investigation ◽

Turbine Blade ◽

Time History ◽

Surface Heat ◽

Blade Surface ◽

Surface Heat Transfer ◽

Effects Of Rotation ◽

Wake Passing

Measurements of turbine blade surface heat transfer in a transient rotor facility are compared with predictions and equivalent cascade data. The rotating measurements involved both forwards and reverse rotation (wake free) experiments. The use of thin-film gauges in the Oxford Rotor Facility provides both time-mean heat transfer levels and the unsteady time history. The time-mean level is not significantly affected by turbulence in the wake; this contrasts with the cascade response to freestream turbulence and simulated wake passing. Heat transfer predictions show the extent to which such phenomena are successfully modelled by a time-steady code. The accurate prediction of transition is seen to be crucial if useful predictions are to be obtained.

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Wear Resistance Performance of Conventional and Non-Conventional Wind Turbine Blades with TiN Nano-Coating

International Journal of Engineering Materials and Manufacture ◽

10.26776/ijemm.02.03.2017.01 ◽

2017 ◽

Vol 2 (3) ◽

pp. 37-48

Author(s):

Muhammad Hasibul Hasan ◽

Shugata Ahmed

Keyword(s):

Surface Roughness ◽

Shear Stress ◽

Wind Turbine ◽

Turbine Blade ◽

Erosion Rate ◽

Blade Surface ◽

Impingement Angle ◽

Nano Coating ◽

Wind Velocities ◽

Sand Particles

Efficiency and durability are critical issues that affect widely-adopted aerofoil-power generator as a sustainable source of electrical power. Even though high wind power density can be achieved; installing wind turbines in desert condition has difficulties including thermal variation, high turbulence and sand storms. Sand blasting on turbine blade surface at high velocities causes erosion resulting turbine efficiency drop. Damage-induced erosion phenomena and aeroelastic performance of the blades needed to be investigated. Suitable coating may prevent erosion to a great extent. A numerical investigation of erosion on NACA 4412 wind turbine blade has been performed using commercial computational fluid dynamics software ANSYS FLUENT 14.5 release. Discrete phase model (DPM) has been used for modelling multi-phase flow of air and sand particles over the turbine blade. Governing equations have been solved by finite volume method (FVM). Conventional 30-70% glass fibre resin and non-conventional jute fibre composite have been used as turbine blade material. Sand particles of diameter have been injected from 20, 30, 45, 60 and 90 degree angles at 500C temperature. Erosion rate, wall shear stress and strain rate have been calculated for different wind velocities and impingement angles. Simulation results for higher velocities deviate from the results observed at lower wind velocities. In simulation, erosion rate is highest for impingement angle at low wind velocities, which has been validated by experiment with a mean absolute error (MAE) of 5.56%. Erosion rate and wall shear stress are higher on jute composite fibre than glass fibre resin. Developed shear stress on wind turbine blade surface is highest for impingement angle at all velocities. On the other hand, exerted pressure on turbine blade surface is found highest for 9 angle of attack. Experimental results, with or without Titanium nitride(TiN) nano-coating, also revealed that surface roughness augments with increasing impingement angles. Nano-coating (TiN) by RF sputtering technique reduced the surface roughness significantly as oppose to uncoated samples. Highest roughness has been observed on uncoated blade surface collided with 0.3-0.69 mm diameter brown aluminium oxide particles.

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Effect of Surface Roughness and Electroless Ni–P Plating on the Bonding Strength of Bi–Te-based Thermoelectric Modules

Coatings ◽

10.3390/coatings9030213 ◽

2019 ◽

Vol 9 (3) ◽

pp. 213

Author(s):

Sung Bae ◽

Sungsoon Kim ◽

Seong Yi ◽

Injoon Son ◽

Kyung Kim ◽

...

Keyword(s):

Thin Film ◽

Surface Roughness ◽

Bonding Strength ◽

Molten Solder ◽

Bonding Interface ◽

Thermoelectric Modules ◽

Solder Reaction ◽

Electroless Ni ◽

Plating Layer ◽

Effect Of Surface

In this study, electroless-plating of a nickel-phosphor (Ni–P) thin film on surface-controlled thermoelectric elements was developed to significantly increase the bonding strength between Bi–Te materials and copper (Cu) electrodes in thermoelectric modules. Without electroless Ni–P plating, the effect of surface roughness on the bonding strength was negligible. Brittle SnTe intermetallic compounds were formed at the bonding interface of the thermoelectric elements and defects such as pores were generated at the bonding interface owing to poor wettability with the solder. However, defects were not present at the bonding interface of the specimen subjected to electroless Ni–P plating, and the electroless Ni–P plating layer acted as a diffusion barrier toward Sn and Te. The bonding strength was higher when the specimen was subjected to Ni–P plating compared with that without Ni–P plating, and it improved with increasing surface roughness. As electroless Ni–P plating improved the wettability with molten solder, the increase in bonding strength was attributed to the formation of a thicker solder reaction layer below the bonding interface owing to an increase in the bonding interface with the solder at higher surface roughness.

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