A Correlation of Mixing Noise From Coannular Jets With Inverted Flow Profiles

摘要

This report correlates data for jet mixing noise from coannular jets with inverted flow velocity profiles (IVP's). The acoustic performance of coan¬nular jets is compared to the performance of a hypothetical single jet with the same total mass flow, thrust, and total enthalpy flow as the coannular jet. The study shows that coannular jets with velocity ratios greater than 1.2 produce less noise than their corresponding equivalent jets and that optimum noise reduction of coannular jets in the data set occurs within a range of equivalent velocities between 500 and 700 meters per second and velocity ratios between 1.6 and 2.3. The maximum sound power reduction is found to be about 4 decibels.