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Author: James E. Brunk Publisher: ISBN: Category : Aerodynamic heating Languages : en Pages : 168
Book Description
Two HTV-1 Hypersonic Test Vehicles, Rounds A-40 and A-41, were flown at Holloman AFB in October 1959, with blunted and sharp 20 degree half angle nose cones, respectively. Round A-40 also incorporated nose cone incidence and a pitch disturber rocket. A maximum flight velociety of 5800 feet per second was attained, corresponding to a local shap cone Mach number and unit Reynolds number of 3.4 and 50 x 10(6) per foot respectively. Fligh dynamics data for the second stage of Round A-40 were obtained from analyses of the vector angle of attack history. The measured maximum trim angle of attack (1.5 degrees) agreed closely with the predicted trim based on an elastic structure and a nose cone incidence of 0.36 degrees. Surface temperatures and aerodynamic heating rates were obtained for one station and three radial positions on the conical portion of the blunted nose cone (Round A-40) and at 3 stations on each of the two longitudinal rays on the sharp cone (Round A-41). In addition, the temperature and heating rates were determined on the cylindrical portion of the Round A-41 payload and on the base of on Stage II fin for both vehicles. The maximum heating rate for the sharp cone was about 30 percent greater for the blunt cone as a result of higher local Mach numbers and Reynolds numbers on the sharp cone. Correlation of the blunted cone circumferential heating rates with the measured angle of attack showed that only a small increase in heating rate (less than about 5 percent increase from the zero angle of attack heating rate) occurs on the windward ray for turbulent heating conditions. The measured decrease in Stanton mumber with increasing Reynolds number (running length) for the sharp cone was found to be in close agreement with turbulent flow theory. Boundary layer transition reversal from turbulent to laminar flow was experienced on both the sharp and blunted tip cones. Transition reversal for the sharp cone, which had almost twice the local Mach number of the blunted cone, was found to occur at an enthalpy ratio, hw/hr, 30 percent greater than for the blunted cone. For both cones turbulent flow occurred within the Mach number and enthalpy region for complete stability of two dimensional disturbance as defined by Dunn and Lin. The possible effects of surface roughness in producing the observed transition reversal are discussed.
Author: James E. Brunk Publisher: ISBN: Category : Aerodynamic heating Languages : en Pages : 168
Book Description
Two HTV-1 Hypersonic Test Vehicles, Rounds A-40 and A-41, were flown at Holloman AFB in October 1959, with blunted and sharp 20 degree half angle nose cones, respectively. Round A-40 also incorporated nose cone incidence and a pitch disturber rocket. A maximum flight velociety of 5800 feet per second was attained, corresponding to a local shap cone Mach number and unit Reynolds number of 3.4 and 50 x 10(6) per foot respectively. Fligh dynamics data for the second stage of Round A-40 were obtained from analyses of the vector angle of attack history. The measured maximum trim angle of attack (1.5 degrees) agreed closely with the predicted trim based on an elastic structure and a nose cone incidence of 0.36 degrees. Surface temperatures and aerodynamic heating rates were obtained for one station and three radial positions on the conical portion of the blunted nose cone (Round A-40) and at 3 stations on each of the two longitudinal rays on the sharp cone (Round A-41). In addition, the temperature and heating rates were determined on the cylindrical portion of the Round A-41 payload and on the base of on Stage II fin for both vehicles. The maximum heating rate for the sharp cone was about 30 percent greater for the blunt cone as a result of higher local Mach numbers and Reynolds numbers on the sharp cone. Correlation of the blunted cone circumferential heating rates with the measured angle of attack showed that only a small increase in heating rate (less than about 5 percent increase from the zero angle of attack heating rate) occurs on the windward ray for turbulent heating conditions. The measured decrease in Stanton mumber with increasing Reynolds number (running length) for the sharp cone was found to be in close agreement with turbulent flow theory. Boundary layer transition reversal from turbulent to laminar flow was experienced on both the sharp and blunted tip cones. Transition reversal for the sharp cone, which had almost twice the local Mach number of the blunted cone, was found to occur at an enthalpy ratio, hw/hr, 30 percent greater than for the blunted cone. For both cones turbulent flow occurred within the Mach number and enthalpy region for complete stability of two dimensional disturbance as defined by Dunn and Lin. The possible effects of surface roughness in producing the observed transition reversal are discussed.
Author: E. R. Van Driest Publisher: ISBN: Category : Aerodynamics, Supersonic Languages : en Pages : 108
Book Description
Experiments carried out in the 12-inch supersonic wind tunnel to investigate the effect of three dimensional roughness elements (spheres) on boundary-layer transition on a 10-degree (apex angle) cone without heat transfer are described. The local Mach number for these tests was 2.71. The data show clearly that the minimum (effective) size of trip required to bring transition to its lowest Reynolds number varies power of the distance from the apex of the cone to the trip. Use of available data at other Mach numbers indicates that the Mach number influence for effective tripping is taken into account by a simple expression. Some remarks concerning the roughness variation for transition on a blunt body are made. Finally, a general criterion is introduced which gives insight to the transition phenomenon and anticipates effects of external and internal disturbances, Mach number transfer.
Author: John J. Bertin Publisher: AIAA ISBN: 9781563470363 Category : Science Languages : en Pages : 644
Book Description
A modern treatment of hypersonic aerothermodynamics for students, engineers, scientists, and program managers involved in the study and application of hypersonic flight. It assumes an understanding of the basic principles of fluid mechanics, thermodynamics, compressible flow, and heat transfer. Ten chapters address: general characterization of hypersonic flows; basic equations of motion; defining the aerothermodynamic environment; experimental measurements of hypersonic flows; stagnation-region flowfield; the pressure distribution; the boundary layer and convective heat transfer; aerodynamic forces and moments; viscous interactions; and aerothermodynamics and design considerations. Includes sample exercises and homework problems. Annotation copyright by Book News, Inc., Portland, OR