Subsonic and supersonic jets and supersonic suppressor characteristics

摘要

Convergent and parallel flow nozzles were used with room temperature air to investigate the flow and acoustic characteristics over a Mach number range of 0.6 to 1.5. For subsonic jets the maximum sound pressure levels occurred at 19.1 from the axis and the sound pressure level decreased monotonically with increasing angle. But for supersonic jets the sound pressure was nearly constant over most of angular positions. The power spectra for subsonic jets were similar with the peak occurring at 4 KHz and for a Mach 1.4 jet the peak occurred at 5 KHz. Near field sound pressure level distributions were quite similar for subsonic jets, but for supersonic jets the distributions were quite different. Mean and fluctuating velocity contours were determined for a convergent nozzle with the impact and piezoelectric impact pressure gage probes for Mach numbers of 0.6 to 1.4. A supersonic suppressor of 191 tubes and shrouds was investigated at Mach numbers of 1.4 and 0.7.