An experimental study on aeroacoustics and shock dynamics associated with hartmann whistle

Experiments are conducted to study the mechanisms involved in the workings of a cylindrical Hartmann whistle at two different NPRs. The focus is more on the shock dynamics associated with the Hartmann whistle phenomenon. The sound field of the order of 130 dB is produced. Distinct peaks are observed at the fundamental frequency as well as the higher harmonics. The relationship between the flow pattern seen form Schlieren data with the acoustic measurements is highlighted. The cavity gas oscillation and the high speed Schlieren data showed the non-sinusoidal movement pattern of the stand-off shock. The static pressure variation in an under-expanded jet is found to be responsible for non-sinusoidal shock movement.