Correlation of Recent and Historical Hemispherical Nose Tip Distributed Roughness Transition Data

2019 ◽  
Vol 56 (3) ◽  
pp. 664-686 ◽  
Author(s):  
Brian R. Hollis
Keyword(s):  
Roughness Transition

Turbulence at a roughness transition in a depth limited flow over a gravel bed

Geomorphology ◽  
1996 ◽  
Vol 16 (2) ◽  
pp. 175-187 ◽  
Author(s):  
André Robert ◽  
AndréG. Roy ◽  
Bernard De Serres
Keyword(s):  
Gravel Bed ◽  
Roughness Transition

scholarly journals Simplified Approach to Predicting Rough Surface Transition

2008 ◽  
Author(s):  
R. J. Boyle ◽  
M. Stripf
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Numbers ◽  
Simplified Approach ◽  
Roughness Transition ◽  
Experimental Heat ◽  
Surface Transition ◽  
Regular Roughness ◽  
Statistical Sense ◽  
Physical Height

Turbine vane heat transfer predictions are given for smooth and rough vanes where the experimental data show transition moving forward on the vane as the surface roughness physical height increases. Consistent with smooth vane heat transfer, the transition moves forward for a fixed roughness height as the Reynolds number increases. Comparisons are presented with published experimental data. Some of the data are for a regular roughness geometry with a range of roughness heights, Reynolds numbers, and inlet turbulence intensities. The approach taken in this analysis is to treat the roughness in a statistical sense, consistent with what would be obtained from blades measured after exposure to actual engine environments. An approach is given to determine the equivalent sand grain roughness from the statistics of the regular geometry. This approach is guided by the experimental data. A roughness transition criterion is developed, and comparisons are made with experimental data over the entire range of experimental test conditions. Additional comparisons are made with experimental heat transfer data, where the roughness geometries are both regular as well as statistical. Using the developed analysis, heat transfer calculations are presented for the second stage vane of a high pressure turbine at hypothetical engine conditions.

scholarly journals Discrete-Roughness Transition for Hypersonic Flight Vehicles

2008 ◽  
Vol 45 (2) ◽  
pp. 216-227 ◽  
Author(s):  
Scott A. Berry ◽  
Thomas J. Horvath
Keyword(s):  
Roughness Transition ◽  
Hypersonic Flight ◽  
Flight Vehicles

scholarly journals Characterization of a wind turbine wake evolving over an intertidal zone performed with dual-lidar observations

2017 ◽  
Author(s):  
Changzhong Feng ◽  
Bingyi Liu ◽  
Songhua Wu ◽  
Jintao Liu ◽  
Rongzhong Li ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Intertidal Zone ◽  
Sea Water ◽  
Roughness Transition ◽  
Turbine Wake ◽  
Lidar Observations ◽  
Rising Sea Level ◽  
Wind Turbine Wake

Abstract. As modern wind power industry quickly develops, it is of high priority to optimize layouts and operations of wind turbines to reduce the influences of wakes induced by upstream wind turbines. The wake behaves complicatedly with land ocean-atmosphere interactions. This complex wake could be observed by two or more synchronously operated Doppler lidars. Accordingly, we characterized a wind turbine wake evolving over an intertidal zone performed with dual-lidar observations. Dynamic process of wakes merging that occurred from approximately 1 D (rotor diameter) downstream was captured and analysed. The phenomenon that wake length increased with rising tide was analysed in details. It suggested that the increase of wake length varied with underlying surface roughness transition from mud to sea water as well as the rising sea level. Finally, wake meandering cases were analyzed in detail. Our research shows that the dual-lidar observation technology is a promising remote sensing tool for characterization of complicated wind turbine wakes.

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