On the source modeling technique in Tam & Auriault's fine-scale turbulence jet noise theory

In 1999, Tam and Auriault developed a theory capable of predicting the fine-scale turbulence noise from cold to moderate temperature jets. In this jet noise prediction theory, they proposed a Gauss noise source model function to represent the noise source time-space correlation function mathematically. In 2005, Tam et al. modified the noise model function of Tam and Auriault theory to predict hot jet noise. The calculated results of Tam and Auriault's theory are in good agreement with experimental measurements over a wide range of directions of radiation, jet velocities and temperatures. However, some noticeable deviations still can be observed between the prediction results and experimental data for some cases of single and dual-stream jets. The main objective of this work is to improve the accuracy of the prediction results of Tam and Auriault's theory by modifying the noise source model function. Two alternative noise source model functions are considered here which are proposed by Khavaran et al. and Harper-Bourne. In addition, a frequency dependent length scale proposed by Morris and Boluriaan is applied to the noise source model functions. The effects of above mentioned three noise source model functions are evaluated in Tam and Auriault's theory through comparison with experimental results at several jet Mach numbers for single-stream cold and hot jet. The comparisons indicated that, the usage of frequency dependent length scale can provide better agreement with measurements for some cases. In addition, Khavaran et al's and Harper-Bourne's source model which give good noise prediction for cold jet, are not applicable to the prediction of hot jet noise.