A study of laminar hypersonic cavity flows

Abstract

An experimental investigation of the distributions of pressure, recovery factor, and heattraiisfer coefficient on 20° cones incorporating annular cavities was carried out in helium at MOO = 11 • The effects of Reynolds number, cavity length-depth ratio, and reattachment region geometry were studied. Attention was confined to the laminar, open cavity flow regime. The results showed that the pressure was virtually constant on the cavity floor for a cavity length-depth ratio less than seven. A definite pressure gradient appeared at higher length-depth ratios. The recovery factor was virtually constant within the cavity and downstream and was very close to the laminar attached-flow value. The distribution of heattransfer coefficient showed a pronounced minimum on the cavity floor, falling to about 10 to 20% of the attached-flow value. The heat-transfer coefficient passed through a maximum in the reattachment region, then went asymptotically to a value lower than the attached-flow value. The integrated heat-transfer rate in the separated flow region was in excellent agreement with Chapman's laminar mixing layer theory, being about 55% of the attached-flow value. However, this significant reduction in heat transfer was almost nullified by the increased heat-transfer rates close to reattachment.