NASA-TM-4549

Abstract

The passive venting techniques for shallow cavities that were investigated consisted of (1) porous floors, (2) slot vents at each end of solid floors, (3) slot vents at each end of porous floors, and (4) pipe vents on solid floors. For deep cavities, passive venting techniques that were investigated consisted of (1) lip vents at the outer edges of the front and rear walls of a cavity with a solid floor and (2) lip vents at the outer edges of the front and rear walls of a cavity with a porous floor. The cavity passive venting models were mounted in a flat plate model and were tested at Mach numbers from 0.20 to 0.95. The shallow cavities had lengths of 32.16 and 42.00 in. and a depth of 2.40 in., resulting in cavity length-to-depth ratios (I/h) of 13.40 and 17.50, respectively. The deep cavity had a length of 32.16 in. and a depth of 4.80 in. (I/h = 6.70). All cavities had a width of 9.60 in. Results from the test show that the porous floor and the porous floor combined with slot vents had the greatest effect on the shallow cavity pressure distributions and resulted in distributions that were representative of deeper cavities. The lip vents had little effect on the pressure distributions for the deep cavity with solid or porous floors for most of the test range of Mach number.