Abstract
A noise generation mechanism for a nearly ideally expanded supersonic jet is proposed. It is suggested that the dominant part of the noise of a supersonic jet is generated at two rather localized regions of the jet. These regions are located at distances quite far downstream of the nozzle exit. Large-scale instabilities of the jet flow are believed to be responsible for transferring the kinetic energy of the jet into noise radiation. An analysis based on a simple mathematical model reveals that two large-scale unstable waves are preferentially amplified in a supersonic jet. The rapid growth of these waves causes the oscillations of the jet to penetrate the mixing layer at two locations and to interact strongly with the ambient fluid there. This gives rise to intense noise radiation. Theoretical results based on the proposed noise generation mechanism are found to compare favourably with experimental measurements. A simple scaling formula is also derived.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Reference32 articles.
1. Eggers, J. M. 1966 Velocity profiles and eddy viscosity distributions downstream of a Mach 2.2 nozzle exhausting to quiescent air.N.A.S.A. Tech. Note, D-3601.
2. Berman, C. H. & Ffowcs Williams, J. E. 1970 Instability of two-dimensional compressible jet.J. Fluid Mech. 42,151.
3. Ffowcs Williams, J. E. 1963 The noise from turbulence convected a t high speed.Phil. Trans. Roy. Soc. A255,469.
4. Gill, A. E. & Drazin, P. G. 1965 Note on instability of compressible jets and wakes to long-wave disturbances.J. Fluid Mech. 22,415.
5. Ollerhead, J. B. 1966 Some shadowgraph experiments with a cold supersonic jet.Wyle Lab. Res. Rep. WR66–44.
Cited by
103 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献