Gas dynamics of laser exhaust external to spacecraft
By: Shaul Abramovich
Contributors: Naval Postgraduate School (U.S.). Dept. of Aeronautics
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1985
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 107
Subjects: EXHAUST PLUMES; GAS DYNAMIC LASERS; SPACE ENVIRONMENTS; METHOD OF CHARACTERISTICS
Other titles: NPS-67-84-006CR.
Description: Some procedures have been developed to analyze the flowfield of highly underexpanded      axisymmetric ring jets operated at high altitudes. The Method of Characteristics (MOS) was      used to compute the Prandtl Meyer expansion fan and flow parameters in that region. The      MOC may also be used to obtain some indications about the repetitive expansion      compression behavior of the jet as well as the divergent shape of the compression part      downstream, when the ambient pressure goes below certain limits. The continuum methods      may be used as far as the limit where translational equilibrium ceases to exist. The breakdown      of the continuum theory may be evaluated using the experimental breakdown parameter.      Beyond this limit, the molecular Direct-Simulation-Monte-Carlo method (DSMC) is applied.      The axisymmetric Monte Carlo Simulation begins outside the nozzle, where the breakdown      parameter has a value of approximately 0.05. The actual shape of this breakdown limit is a      closed lobe surface which starts at the nozzle lips, approximately follows a specific Mach      wave in the Prandtl Meyer fan and closes back to the axis far downstream. Because our      interest is limited to the close vicinity of the corners, there the shape of this limit may be      approximated to a straight line (for an axisymmetric flow making cone). The program runs as      far as the collision frequency is still high and the mean free path is low compared with the size      of the cells. Beyond this limit the flow may be regarded as collisionless, and the flux towards      the solid wall may be computed directly.
Notes: Cover title.

"NPS-67-84-006CR."

"November 1985."

AD A167 143.

Includes bibliographical references (p. 103-105).

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