Abstract
In this study we show how accurate jet noise predictions can be achieved within Goldstein’s generalized acoustic analogy formulation for heated and unheated supersonic jets using a previously developed asymptotic theory for the adjoint vector Green’s function. In this approach, mean ﬂow nonparallelism enters the leading order dominant balance producing enhanced ampliﬁcation at low frequencies, which we believe corresponds to the peak sound at small polar observation angles. We determine all relevant mean ﬂow and turbulence quantities using Large Eddy Simulations of two axisymmetric round jets at ﬁxed jet Mach number and diﬀerent nozzle temperature ratios. Certain empirical coeﬃcients that enter the turbulence length scales formula are tuned for good agreement with the farﬁeld noise data. Our results indicate that excellent jet noise predictions are obtained using the asymptotic approach, remarkably, up to a Strouhal number of 0.5.
Original language  English 

Title of host publication  Studying Turbulence using Numerical Simulation Databases  XVI 
Subtitle of host publication  Proceedings of the 2016 Summer Program 
Place of Publication  Stanford, California 
Number of pages  10 
Publication status  Published  31 Dec 2016 
Keywords
 jet noise predictions
 Goldstein’s generalized acoustic analogy formulation
 adjoint vector Green’s function
 asymptotic approach
 turbulence
 mean flow
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Profiles

Mohammed Afsar
Person: Academic