Accession Number:

AD0645731

Title:

CIRCULAR-ARC JET FLAPS AT SUPERSONIC SPEEDS - TWO DIMENSIONAL THEORY,

Descriptive Note:

Corporate Author:

MICHIGAN UNIV ANN ARBOR OFFICE OF RESEARCH ADMINISTRATION

Personal Author(s):

Report Date:

1966-07-01

Pagination or Media Count:

76.0

Abstract:

An inviscid theory of jet-flap interaction is developed for a two-dimensional jet which issues from a curved nozzle and follows a circular-arc path such that the centrifugal force is in equilibrium with the pressure difference between a high pressure separated flow region along the upstream edge of the jet and a low pressure base pressure region along the downstream edge. The theory is based on empirical relations for the pressure in the separated flow region ahead of the jet flap. Results of a large number of numerical calculations are presented to show the effects of the various parameters. The most favorable interaction effects are shown to be associated with laminar separation ahead of weak jets at hypersonic speeds, but even for turbulent separation ahead of a strong jet lift coefficient .15 the normal force due to the jet is predicted to approach 7 times the thrust of an ideal jet in a vacuum, when the jet is inclined forward so that it has a substantial upstream component. The theoretical results for circular-arc jet flaps are compared with those for flaps issuing from straight nozzles at the same pressure as that of the upstream separated flow region, and the two types of fully-expanded jets are found to give almost identical results. The lifting efficiency of a jet flap is predicted to compare favorably with that of a flat plate airfoil at angle of attack, for high lift coefficients at hypersonic speeds. Author

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE