HYPERSONIC RESEARCH SUMMARY. Final Report
Studies were made of pseudo-one-dimensional nozzle flows of pure dissociating oxygen. Equilibration of initially frozen flow by relaxation in a parallel duct was investigated. The results suggested that such equilibration of frozen flow would require ducts of impractical length as regards boundary layer development. Approximate methods developed for the annlysis of such flows were applied to calculation of nonequilibrium ainflow in typical hypersonic wind tunnel nozzles. On the basis of a simplified kinetic model of air, the resuits indicate that high resservoir pressures are essential if serious nonequilibrium effects are to be avoided in hypersonic wind-tunnel test flows at high stagnation enthalpies. The above mentioned approximate methcds were applied to study the penformance of a hydrogen rocket at low chamber pressures. At low pressures the chamber enthalpy is substantially increased by large dissociation. If the dissociation energy is recovered in flow expansion through the nozzle, large increases in specific impulse result. The results of the study showed that nonequilibrium effects (freezing of dissociation level) severly limit the impulse gain attainable in this way. The specific impulse did not increase monotonically with decreasing chamber pressure at constant chamber temperature but exhibited a well-defined maximum value. A "radiation probe" apparatus, utilizing ultraviolet absorption, was constructed for the measurement of the temperature of air in hypersonic flows without disturb-ing the flow conditions. The absorptive properties of hightemperature air, determined chiefly by the effects of O/sub 2/, were investigated up to 4000 tained K. A generalized wave equation was derived for sound disturbances in a gas when relaxation effects connected with molecular vibration or dissociation are importunt. Solutions involving discontinuous wave fronts are presented and it was shown that, under certain assunnptions, the complete wave equation reduces to a variant of the telegraph equation. Solutions were found for disturbance fields produced by a wavy wall in subsonic and supersonic flow, and a simple wedge in supersonic flow. The results showed that the equilibration process is strongly dependent on the particular flow in which relaxation occurs. Measurements of laminar and turbulent heat transfer to the walls of a shock tube were obtained over a wide range of operating conditions in air, argon, and oxygen, utilizing the methods of thin-- film resistance thermometry. Boundary-layer transition datu were obtained over a wide range of values of the ratio of wall-to-free-stream temperatures and for many pressures. The transition results showed that at low cooling rates, transition depends chiefly on Reynolds number, while extreme cooling rates provide a marked stabilization. An effect of unit Reynolds number on the transition Reynolds number was observed at the lower shock Mach numbers. Thin coatings of silicon dioxide successfully insulated the thin-film gages frcm the ionized gas which approached temperatures to 3000 tained K. A molecular beam apparatus for determining equilibrium gas interactions at 1 to 10 ev was designed. (C.J.G.)
- Research Organization:
- Cornell Aeronautical Lab., Inc., Buffalo
- DOE Contract Number:
- AF18(603)-141
- NSA Number:
- NSA-14-019534
- OSTI ID:
- 4163582
- Report Number(s):
- CAL-AD-1118-A-11; AFOSR-TR-60-
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-60
- Country of Publication:
- United States
- Language:
- English
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