The Design and Performance of a Convergent-Divergent Nozzle for the Mechanical Engineering Laboratory Shock Tube

The installation and test of a two-dimensional, sharp-edge-throat, Mach 3 nozzle in the Mechanical Engineering Laboratory shock tube is presented. Preliminary tests on an abrupt area reduction resulted in the selection of a 1-inch nozzle throat height. Wooden nozzle blocks were installed and test runs were conducted with a constant chamber pressure and varied channel pressure to produce incident shock waves of increasing strength. Analysis of high-speed motion pictures indicates that the nozzle test section Mach number is independent of incident shock strength; however, available and usable test times increase with increasing incident shock strength. A plenum chamber attached to the low-pressure channel helped produce Mach 2.6-2.8 flows for up to 18 milliseconds.