Comparison of Hot and Cold Subsonic Jets in External Flow with Reference to Jet Engine Simulation

摘要

The effect of jet heating and external flow on the mean flow properties of a subsonic jet was studied. A 60 mm diameter jet was tested in a wind tunnel at wind speeds of 0 and 60 m/sec. Jet Mach numbers varied between 0.44 and 0.94 and jet total temperatures were 310 and 860 K. Velocity and temperature profiles in the jet were determined for up to 20 nozzle diameters downstream. Jet Reynolds numbers based on nozzle diameter were larger than 400,000 which is considered high enough to obtain results which are independent of Reynolds number. Semiempirical relations were obtained for the center line velocity decay, the location of the jet boundary and the direction of the streamlines at the jet boundary. From these relations the shortcomings of simulation of a hot engine exhaust jet by a cold air jet in wind tunnel experiments can be estimated.