Measurements of roughness noise

被引:28
作者
Devenport, William J. [1 ]
Grissom, Dustin L. [1 ]
Alexander, W. Nathan [1 ]
Smith, Benjamin S. [1 ]
Glegg, Stewart A. L. [2 ]
机构
[1] Virginia Tech, Aerosp & Ocean Engn Dept, Blacksburg, VA 24061 USA
[2] Florida Atlantic Univ, Dept Ocean & Mech Engn, Boca Raton, FL 33431 USA
关键词
TURBULENT BOUNDARY-LAYER; SURFACE-ROUGHNESS; WALL-JET; SOUND; FLOW; PRESSURE; SMOOTH;
D O I
10.1016/j.jsv.2011.03.017
中图分类号
O42 [声学];
学科分类号
070206 ; 082403 ;
摘要
Experiments have been performed on the roughness noise produced by a two-dimensional turbulent wall jet boundary layer flowing over short fetches of sandpaper roughness. A range of rough surface sizes were studied from hydrodynamically smooth through fully rough. Velocity measurements were made to document the form of the wall jet boundary layer and the influence of the roughness upon it. Acoustic measurements showed background noise levels to be very low so that the sound produced by the rough surfaces could be clearly detected with signal to noise ratios as large as 20 dB. Even hydrodynamically smooth roughness was found to produce noise, conclusively indicating the presence of scattering as a source mechanism. Variations of the roughness noise spectra with flow speed and roughness size are found to be inconsistent with any simple parameter scaling. Boundary layer wall pressure fluctuation measurements made within the roughness fetches reveal a spectral form quite different than the roughness noise, and fluctuation levels some 50-70 dB higher. Despite these differences the wall pressure and roughness noise are found to be very simply related, at least at lower frequencies ( < 6 kHz). The roughness noise spectrum varies closely as the product of the wall pressure spectrum, the frequency squared, and the mean-square roughness height. This is the scaling predicted by scattering theory and implies a major simplification to the problem of roughness noise prediction for stochastic surfaces. (C) 2011 Elsevier Ltd. All rights reserved.
引用
收藏
页码:4250 / 4273
页数:24
相关论文
共 32 条
[1]  
Alexander W. N., 2009, THESIS VIRGINIA TECH
[2]  
ANDERSON J, 2007, ASME MECH ENG C EXP
[3]  
[Anonymous], 1998, Cambridge Monographs on Mechanics
[4]  
BEARMAN PW, 1971, DISA INFORM, V11, P25
[5]  
Blake W. K., 1970, Journal of Fluid Mechanics, V44, P637, DOI 10.1017/S0022112070002069
[6]  
Blake WK., 1986, MECH FLOW INDUCED SO
[7]  
Bradshaw P, 1962, AERONAUTICAL RES COU, V3252
[9]  
COLE LD, 1980, SAD288E1942 NAV SHIP
[10]   Measuring surface pressure with far field acoustics [J].
Devenport, William ;
Wahl, Elisabeth A. ;
Glegg, Stewart A. L. ;
Alexander, W. Nathan ;
Grissom, Dustin L. .
JOURNAL OF SOUND AND VIBRATION, 2010, 329 (19) :3958-3971