HIGH TEMPERATURE, LOW DENSITY BOUNDARY-LAYER CONTROL BY CRYOGENIC PUMPING
Abstract
Results are presented of a study of the flow in a hypersonic nozzle operated at low densities and high stagnation enthalpy levels with both natural and controlled boundary layers. The boundary-layer control was established by cryogenic pumping on the nozzle walls, using liquid hydrogen as the cryogen. A flow calibration procedure was evolved for this nozzle which included a fully frozen (in vibration) nitrogen flow model, large low density corrections to pitot and static pressure measurements, and a non-Sutherland viscosity variation. The regimes of isentropic flow in the nozzle were identified by this calibration, and flow conditions within these regimes are given. The boundary- layer control technique permitted the attainment of indicated Knudsen numbers one order of magnitude greater than those produced with no boundary-layer control. At the lowest levels of static density produced in the nozzle with boundary-layer control, evidence of an entropy-increasing process was found which was tentatively identified as a departure from rotational equilibrium in the flow.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1966
- Accession Number
- AD0643963
Entities
People
- J. E. Shepard
- R. E. Dix
- W. N. Macdermott
Organizations
- Arnold Engineering Development Complex