H.K. Tanna

TL;DR: In this article, the authors derived a scaling formula that the intensity of shock associated noise varies as (Mj2 − Md2)2 where Mj and Md are the fully expanded jet operating Mach number and nozzle design Mach number, respectively.

TL;DR: In this paper, the coannular jet provides the maximum noise reduction relative to the equivalent single jet under inverted and normal-velocity-profile conditions, provided the inner stream is operated at a Mach number just above unity, regardless of all the other jet operating conditions.

TL;DR: In this article, the reduction of shock-associated noise in inverted-velocity-profile coannular jets is quantified and explained by conducting extensive optical and acoustic measurements for a suitable range of outer-stream and inner-stream presure-ratio combinations, and by interpreting the measured noise results with the aid of new theoretical models.

TL;DR: In this article, an experimental and theoretical investigation of shock-associated noise of inverted-profile coannular jets is described, and it is theoretically established that this sudden change in the shock structure and hence the decrease in shock associated noise would occur when the primary jet flow is just slightly supersonic regardless of the Mach number and temperature of the fan stream.