Static pressure and velocity characteristics of circular nozzles for high velocity/low volume exhaust ventilation

Static pressure and velocity characteristics of circular exhaust nozzles were studied for average face velocities ranging 50-125 m/sec (10 000-25 000 fpm). Experimental nozzle variations included: (a) seven profile shapes having 2.54 cm (1.0 inch) inside diameter, and (b) five plain profiles of different size, 1.27-3.81 cm (0.50-1.50 inch) inside diameter. Plain and flanged nozzles experienced formation of pronounced vena contracta; flared and rounded nozzles did not. Nondimensional centerline velocity gradients were affected strongly by variations in nozzle shape, but were insensitive to changes in nozzle size and face velocity. Profile shape and size variations significantly affected overall nozzle static pressure loss, with the most pronounced effects for wedge-shaped inlets. Empirical representations were determined for velocity and static pressure loss data to permit calculations for nozzle design.