Measurements of the Distribution of the Noise Source Intensities in Co-Axial Double Jet by Means of a Reflector-Type Directional Microphone System
1982 Volume 30 Issue 337 Pages 96-103
Details
1982 Volume 30 Issue 337 Pages 96-103
An investigation concerning the noise source distribution of a coaxial double jet in subsonic speed was conducted by means of a reflector-type directional microphone system which operated on the image principle of an elliptical concave reflector of diameter of 40cm.
The effect of the velocity ratio of the bypass jet to the main jet on the apparent source strength distribution for flow direction on the jet axis was clarified in one-third octave band and overall frequency. The distribution of pressure fluctuations in the jet flow was also compared with that of the noise source intensities. The sound power generated by unit axial length of the jet flow was calculated by an iterative technique with the measured noise source distribution and the directional characteristics of the microphone. And, the amount of the noise reduction was estimated. The calculated results agreed with the measurement by the non-directional microphone.
