| Abstract: | Under engineering conditions the surfaces over which fluids flow are not usually hydraulically smooth. In this connection it is important to investigate the generation of sound by a turbulent boundary layer on a rough surface. Turbulent flow over a deformed surface creates dipole sources of sound, which may considerably increase the acoustic emission as compared with the quadrupole emission from a boundary layer on a smooth plate 1, 2]. In the case of sandy roughness estimates of the acoustic field are usually based on the energy summation of the fields generated by flow over the individual roughness elements 3, 4]. In this case not easily verifiable assumptions are made concerning the nature of the turbulent flow near the roughness, and the intensity of the emission is found correct to a constant factor subject to experimental determination. In the present study, in order to calculate the acoustic emission of a boundary layer on a surface with sandy roughness, it is proposed to employ the available experimental data on the cross of the surface pressure.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 20–26, September–October, 1985. |
