Decomposition of modal acoustic power due to cascade–turbulence interaction

Frequency-domain computation of inflow broadband noise due to interaction of a rectilinear cascade of flat plates with incident turbulence

“…4, acoustic power spectra predicted using the present three-dimensional model are compared with those using the previous two-dimensional formulation [7,8]. The parameters used in this calculation followed the baseline case used in the last section, shown in Table 1, except that the mean square value of turbulence velocity 2 w was changed to…”

“…Extending the previous works [7,8] based on two-dimensional theory, this paper investigates the broadband noise due to the interaction between convected turbulent gusts and a rectilinear cascade of flat plates bounded by two parallel walls. An analytic formulation for the acoustic power spectrum due to this three-dimensional turbulence-cascade interaction is derived.…”

“…Cheong et al [7] generalized Smith's theory to broadband noise, defined the concept of critical frequency, and made a full investigation on modal acoustic power (MAP). Cheong et al [8] also made a modaldecomposition analysis to assess the effects of its subcomponents on modal acoustic power.…”

“…An analytic formulation for the acoustic power spectrum due to this turbulence-cascade interaction is derived, which can be used to assess the effects of the span-wise wavenumber components of ingesting turbulent gust on the overall acoustic power spectrum. This three-dimensional theory is based on the two-dimensional theory of Cheong et al (2006Cheong et al ( , 2009. The threedimensional model is shown to provide a close fit to the measured spectrum of rotor-stator interaction.…”

“…The threedimensional model is shown to provide a close fit to the measured spectrum of rotor-stator interaction. The predictions using this threedimensional model are also compared with those using the previous two-dimensional model by Cheong et al (2006;2009). Through this comparison, it is found that the contributions to the acoustic power of the span-wise wavenumber components of incident turbulent gust are increased as the frequency is augmented, which is mainly due to three-dimensional dispersion-relation characteristics of acoustic waves.…”