Statis pressure, velocity, and noise characteristics of rectangular nozzles for high velocity/low volume exhaust...

Static pressure, velocity, and noise characteristics of rectangular exhaust nozzles were studied for average face velocities (V0) ranging 25-150 m/sec (5000-30 000 fpm). Experimental nozzle variations included plain and flanged profile shapes having width-to-length ratios (WLR) of 1.0, 0.50, 0.25, and 0.10. Centerline static pressures for all nozzles indicated formation of pronounced vena contracta in post-entry airflow. Empirical representations were determined for the centerline velocity gradient into the nozzles, which became more gradual with decreasing WLR. Nozzle noise levels varied with V0, exhibiting a "peaking" characteristic indicative of aerodynamic "choking". Flanges were found to have significant effects upon nozzle performance.