An Experimental Study of Airfoil and Endwall Heat Transfer on a Linear Turbine Blade Cascade — Secondary Flow and Surface Roughness Effects

2010 ◽  
Vol 41 (8) ◽  
pp. 867-887 ◽  
Author(s):  
Marco Lorenz ◽  
Achmed Schulz ◽  
Hans-Jorg Bauer
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Surface Roughness ◽  
Secondary Flow ◽  
Turbine Blade ◽  
Roughness Effects ◽  
Blade Cascade

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade— Part I: External Heat Transfer

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
M. Lorenz ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Surface Roughness ◽  
Turbine Blade ◽  
Rough Surfaces ◽  
External Heat ◽  
Roughness Height ◽  
Roughness Effects ◽  
External Heat Transfer

The present experimental study is part of a comprehensive heat transfer analysis on a highly loaded low pressure turbine blade and endwall with varying surface roughness. Whereas a former paper (Lorenz et al., 2009, “An Experimental Study of Airfoil and Endwall Heat Transfer in a Linear Turbine Blade Cascade—Secondary Flow and Surface Roughness Effects,” International Symposium on Heat Transfer in Gas Turbine Systems, Aug. 9–14, Antalya, Turkey) focused on full span heat transfer of a smooth airfoil and surface roughness effects on the endwall, in this work further measurements at the airfoil midspan with different deterministic surface roughness are considered. Part I investigates the external heat transfer enhancement due to rough surfaces, whereas part II focuses on surface roughness effects on aerodynamic losses. A set of different arrays of deterministic roughness is investigated in these experiments, varying the height and eccentricity of the roughness elements, showing the combined influence of roughness height and anisotropy of the rough surfaces on laminar to turbulent transition and the turbulent boundary layer as well as boundary layer separation on the pressure and suction side. It is shown that, besides the known effect of roughness height, eccentricity of roughness plays a major role in the onset of transition and the turbulent heat transfer. The experiments are conducted at several freestream turbulence levels (Tu1=1.4–10.1%) and different Reynolds numbers.

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade— Part II: Aerodynamic Losses

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
M. Lorenz ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Surface Roughness ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Roughness Effects ◽  
Aerodynamic Losses

The present experimental study is part of a comprehensive analysis accounting for heat transfer and aerodynamic losses on a highly loaded low pressure turbine blade with varying surface roughness. Whereas Part I focuses on heat transfer measurements at airfoil midspan with different deterministic surface roughnesses, Part II investigates surface roughness effects on aerodynamic losses of the same airfoil. A set of different arrays of deterministic roughness (the same as used in Part I) is investigated in these experiments. The height and eccentricity of the roughness elements are varied, showing the combined influence of roughness height and anisotropy on the losses produced in the boundary layers. It is shown that the boundary layer loss is dominated by the suction side. Therefore, the investigations focus on measurements of the suction side boundary layer thickness at midspan directly upstream of the trailing edge. The experiments are conducted at several freestream turbulence levels (Tu1=1.4–10.1%) and different Reynolds numbers. The measurements reveal that suction side boundary layer thickness is increased by up to 190% if surface roughness shifts the transition onset upstream. However, in some cases, at low Reynolds numbers and freestream turbulence, surface roughness suppresses boundary layer separation and decreases the trailing edge boundary layer thickness by up to 30%.

Experimental Study of Surface Roughness Effects on a Turbine Airfoil in a Linear Cascade: Part I—External Heat Transfer

2010 ◽  
Author(s):  
M. Lorenz ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Surface Roughness ◽  
Rough Surfaces ◽  
External Heat ◽  
Roughness Height ◽  
Heat Transfer Analysis ◽  
Roughness Effects ◽  
External Heat Transfer

The present experimental study is part of a comprehensive heat transfer analysis on a highly loaded low pressure turbine blade and endwall with varying surface roughness. Whereas a former paper [1] focused on full span heat transfer of a smooth airfoil and surface roughness effects on the endwall, in this work further measurements at the airfoil midspan with different deterministic surface roughness are considered. Part I investigates the external heat transfer enhancement due to rough surfaces whereas part II focuses on surface roughness effects on aerodynamic losses. A set of different arrays of deterministic roughness is investigated in these experiments, varying the height and eccentricity of the roughness elements, showing the combined influence of roughness height and anisotropy of the rough surfaces on laminar to turbulent transition and the turbulent boundary layer as well as boundary layer separation on the pressure and suction side. It is shown that — besides the known effect of roughness height — eccentricity of roughness plays a major role in the onset of transition and the turbulent heat transfer. The experiments are conducted at several free-stream turbulence levels (Tu1 = 1.4% to 10.1%) and different Reynolds numbers.

The effect of single-sided ribs on heat transfer and pressure drop within a trailing edge internal channel of a gas turbine blade

2021 ◽  
pp. 1-43
Author(s):  
Suhyun Kim ◽  
Seungwon Suh ◽  
Seungchan Baek ◽  
Wontae Hwang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Secondary Flow ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Sharp Corner ◽  
Trailing Edge ◽  
Edge Channel ◽  
Ribbed Channel

Abstract Convective cooling in a gas turbine blade internal trailing edge channel is often insufficient at the sharp trailing edge. This study examines convective heat transfer and pressure drop within a simplified trailing edge channel. The internal passage has been modeled as a right triangular channel with a 9° angle sharp corner. Smooth baseline and ribbed copper plates were heated from underneath via a uniform heat flux heater and examined via infrared thermography. Non-uniformity in the heat flux due to conduction is corrected by a RANS conjugate heat transfer calculation, which was validated by the mean velocity, friction factor, and temperature fields from experiments and LES simulations. Nusselt number distributions illustrate that surface heat transfer is increased considerably with ribs, and coupled with the vortices in the flow. Heat transfer at the sharp corner is increased by more than twofold due to ribs placed at the center of the channel, due to secondary flow. The present partially ribbed channel utilizes secondary flow toward the corner, and is presumed to have better thermal performance than a fully ribbed channel. Thus, it is important to set the appropriate rib length within the channel.

scholarly journals Numerical investigation of surface roughness effects on heat transfer in a turbine cascade

2019 ◽  
Author(s):  
Arunprasath Subramanian ◽  
Andrea Gamannossi ◽  
Lorenzo Mazzei ◽  
Antonio Andreini
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Numerical Investigation ◽  
Turbine Cascade ◽  
Roughness Effects

scholarly journals Heat Transfer Enhancement by Shot Peening of Stainless Steel

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 584
Author(s):  
Pramote Koowattanasuchat ◽  
Numpon Mahayotsanun ◽  
Sedthawatt Sucharitpwatskul ◽  
Sasawat Mahabunphachai ◽  
Kuniaki Dohda
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Stainless Steel ◽  
Process Parameters ◽  
Shot Peening ◽  
Cfd Simulation ◽  
Cost Effective ◽  
Transfer Coefficients ◽  
Roughness Effects ◽  
Heat Transfer Efficiency

In heat exchange applications, the heat transfer efficiency could be improved by surface modifications. Shot peening was one of the cost-effective methods to provide different surface roughness. The objectives of this study were (1) to investigate the influences of the surface roughness on the heat transfer performance and (2) to understand how the shot peening process parameters affect the surface roughness. The considered specimens were 316L stainless steel hollow tubes having smooth and rough surfaces. The computational fluid dynamics (CFD) simulation was used to observe the surface roughness effects. The CFD results showed that the convective heat transfer coefficients had linear relationships with the peak surface roughness (Rz). Finite element (FE) simulation was used to determine the effects of the shot peening process parameters. The FE results showed that the surface roughness was increased at higher sandblasting speeds and sand diameters.

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