There is now a substantial body of theoretical and experimental evidence that the dominant part of the turbulent mixing noise of supersonic jets is generated directly by the large turbulence structures/instability waves of the jet flow. The relationship between the instability waves and noise of hot jets at moderate supersonic Mach number is examined in Chapters 1 and 2. It is found that the highest sound-pressure-level of the far-field noise occurs at a direction and frequency that closely match the Mach wave radiation direction and frequency of the most amplified instability wave of the jet. The calculations show that for jet Mach number up to 2.0 and jet total temperature to ambient temperature ratio up to 2.5, the Kelvin-Helmholtz instability waves always grow to a higher amplitude than the supersonic instability wave. Numerical results indicate that for hot jets the most amplified wave invariably belongs to the helical mode Kelvin-Helmholtz instability wave. For lower speed hot jets with jet static temperature higher than or equal to the ambient temperature there is also a fair correlation between the Strouhal number at the peak sound-pressure level of the far-field noise and that of the most amplified instability wave. / In Chapters 3, 4, 5 and 6, a broadband jet noise theory is constructed. In this theory, the compressible flow equations with eddy viscosity are used to calculate the wave propagation characteristics of the instability waves. These equations are solved by the method of matched asymptotic expansions. The inner solution is the instability wave solution. The outer solution gives the associated acoustic field. The amplitudes of the instability waves are assumed to be stochastic random functions. The statistical properties of the random amplitude function are determined by the requirement that the wave spectrum at the nozzle exit has no intrinsic length and time scales. The present theory can predict the dominant part of jet mixing noise from first principles up to a single multiplicative constant. The spectra and directivities of a Mach 2 jet at total temperatures of 500K and 1114K are calculated. The numerical results agree favorably with experimental measurements. / Source: Dissertation Abstracts International, Volume: 54-12, Section: B, page: 6317. / Major Professor: Christopher K. W. Tam. / Thesis (Ph.D.)--The Florida State University, 1993.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_77067 |
| Contributors | Chen, Ping., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 132 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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