The effects of small-scale surface roughness on laminar airfoil-scale trailing edge separation bubbles

1998 ◽  
Author(s):  
W. Huebsch ◽  
A. Rothmayer
Keyword(s):  
Surface Roughness ◽  
Small Scale ◽  
Trailing Edge ◽  
Separation Bubbles ◽  
Edge Separation ◽  
Scale Surface

Sea ice small-scale surface roughness estimation based on AMSR-E observations

2013 ◽  
Vol 34 (12) ◽  
pp. 4425-4448 ◽  
Author(s):  
Haibo Bi ◽  
Xiaofeng Yang ◽  
Ziwei Li ◽  
Xuan Zhou
Keyword(s):  
Surface Roughness ◽  
Sea Ice ◽  
Small Scale ◽  
Surface Roughness Estimation ◽  
Scale Surface

scholarly journals Effect of small-scale snow surface roughness on snow albedo and reflectance

2021 ◽  
Vol 15 (2) ◽  
pp. 793-820
Author(s):  
Terhikki Manninen ◽  
Kati Anttila ◽  
Emmihenna Jääskeläinen ◽  
Aku Riihelä ◽  
Jouni Peltoniemi ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Laser Scanner ◽  
Small Scale ◽  
Snow Surface ◽  
Roughness Effects ◽  
Bidirectional Reflectance Factor ◽  
Reflectance Factor ◽  
Bulk Volume ◽  
The Impact ◽  
Scale Surface

Abstract. The primary goal of this paper is to present a model of snow surface albedo accounting for small-scale surface roughness effects. The model is based on photon recollision probability, and it can be combined with existing bulk volume albedo models, such as Two-streAm Radiative TransfEr in Snow (TARTES). The model is fed with in situ measurements of surface roughness from plate profile and laser scanner data, and it is evaluated by comparing the computed albedos with observations. It provides closer results to empirical values than volume-scattering-based albedo simulations alone. The impact of surface roughness on albedo increases with the progress of the melting season and is larger for larger solar zenith angles. In absolute terms, small-scale surface roughness can decrease the total albedo by up to about 0.1. As regards the bidirectional reflectance factor (BRF), it is found that surface roughness increases backward scattering especially for large solar zenith angle values.

Impact of Skin Friction, Tip Clearance and Trailing Edge Losses on Small Scale Cryogenic Axial Turbine Performance

2016 ◽  
Author(s):  
Khalil M. Khalil ◽  
S. Mahmoud ◽  
R. K. Al-Dadah ◽  
Ayad Al Jubori ◽  
K. Rahbar
Keyword(s):  
Surface Roughness ◽  
Energy Storage ◽  
Power Output ◽  
Major Effect ◽  
Tip Clearance ◽  
Small Scale ◽  
Direct Expansion ◽  
Trailing Edge ◽  
Turbine Performance ◽  
And Performance

Cryogenic Energy Storage (CES) technology which uses liquid air/nitrogen as energy carrier has attracted considerable attention recently due to its high exergy density (762kJ/kg) compared to other energy storage technologies. Liquid air/nitrogen occupies about 1/700 of the volume of its gaseous phase making it easier to store and transport. The stored energy can be recovered through a direct expansion process where the expander design and performance have a major effect on the efficiency of the energy conversion process. In this work the effects of surface roughness, tip clearance and trailing edge thickness on the performance of a small scale (tip diameter 40mm, mass flow rate 0.3 kg/s) axial cryogenic turbine have been investigated using mean line 1D analysis and ANSYS CFX 3D modelling where limited data available in the literature. Results showed that stator surface roughness has the highest impact on the turbine performance, where power output and turbine efficiency were significantly reduced as the roughness increased. For example at 20000RPM (design point) with stator roughness value of 0.5mm the efficiency and power output were 87.2% and 1197.7 W while for the same roughness on rotor blade the efficiency and power output were 89.34% and 1198.59 W. Regarding the effect of tip clearance, the efficiency decreases by 2% as the tip clearance increases from 0.35mm to 1mm.

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