An investigation was conducted in a 3.4- by 3.4-inch duct to determine some characteristics of the supersonic flow downstream of four wire-mesh screen nozzles with nominal design Mach numbers in the range between 1.97 and 2.58. Visual data, transverse Mach number and static-pressure distributions at several axial stations, the total-pressure loss across the screens, and axial static-pressure gradients were used to evaluate the flow.nTwo types of disturbance were observed in the flow field;a fine network of interacting expansion and compression waves which formed immediately downstream of the screens and appeared to dissipate within 25 to 40 wave intersections;and relatively strong oblique shock waves that originated at the Junctions of the screens and the walls and were reflected throughout the length of the duct. The distance required for the network of waves to dissipate appeared to decrease with increasing density of the interactions. Regions of fairly uniform flow existed beyond the network in central regions of the shock diamonds.nThe total-pressure loss across the screens (from 22 percent at Mach number 1.58 to 43 percent at Mach number 2.06) recorded at axial stations where the flow was considered most uniform was very large com¬pared with the loss across conventional two-dimensional nozzles. The corresponding Mach numbers (approximately 80 percent of nominal values predicted by one-dimensional isentropic theory over range investigated) reflected, in part, these losses.
展开▼
