COMPUTATION OF SUPERSONIC JET MIXING NOISE FOR AN AXISYMMETRICAL CONVERGENT-DIVERGENT NOZZLE

The turbulent mixing noise of a supersonic jet is calculated for an ax isymmetric convergent-divergent nozzle at the design pressure ratio. A erodynamic computations are performed using the PARC code with a k-eps ilon turbulence model. Lighthill's acoustic analogy is adopted. The ac oustics solution is based upon the methodology followed in the MGB cod e. The source correlation function is expressed as a linear combinatio n of second-order tensors (Ribner's assumption). Assuming separable se cond-order correlations and incorporating Batchelor's isotropic turbul ence model, the source term was calculated from the kinetic energy of turbulence. A Gaussian distribution for the time-delay of correlation was introduced. The CFD solution was used to obtain the source strengt h as well as the characteristic time-delay of correlation. The effect of sound/flow interaction was incorporated using the high frequency as ymptotic solution to Lilley's equation for axisymmetric geometries. Ac oustic results include sound pressure level directivity and spectra at different polar angles. The aerodynamic and acoustic results demonstr ate favorable agreement with experimental data.