A.O.Borisyuk Sound generation by a limited region of disturbed flow in a rigid channel with circular cross-section. Part 1. General theory |
Acoustic bulletin, Vol. 6 ¹ 3, (2003) |
| A general theory of noise generation by a limited region of a disturbed flow in an infinite straight rigid channel with circular cross-section is developed, and quantitative relationships between the characteristics of generated noise field and the parameters of the channel and the flow are found. A disturbed flow is modeled by the distributed quadruple and dipole sources, the characteristics of which are assumed to be known. The cases of uniform and non-uniform distribution of the sources are considered. It is shown that the noise energy does not decrease as the distance from the sources increases, and is equal to a sum of energies of acoustic modes of the channel. As to the energy of the acoustic mode, it consists of three parts. The first part is the energy generated by the volume quadruples, the second one results from the surface dipoles, and the third is conditioned by interaction of the quadruples and the dipoles. The analysis of orders of magnitudes of these parts is carried out for different values of the flow Mach number, and corresponding simplified expressions for the acoustic power are obtained. |
|
KEY WORDS: noise generation, disturbed flow, straight rigid channel, volume quadruple, surface dipole, acoustic power |
| TEXT LANGUAGE: Ukrainian |