Investigation of Modeling Concepts for Plume-Afterbody Flow Interactions.

摘要

A high pressure hot gas supply system has been developed for the 0.5 x 0.5 sq. meters S5 wind tunnel to allow the study of aerodynamic interference effects caused by plume induced separation from propulsive afterbodies. Capable of operating with a variety of gases covering a wide range of specific hear ratios, the facility serves to evaluate the merits and potential of a new plume simulation methodology. Experimental programs carried out with air and Freon-22 for the jet simulation confirmed the correctness of the theory. The accuracy of the modeling extended over wide ranges of jet-to-ambient pressure ratios straddling the design points. Limited tests at small angles of attack (-6 deg < or equal alpha < or equal +6 deg) and with external disturbances in the vicinity of the base plane (fins) appear to support the applicability of the modeling scheme for more complex flow field geometries. Beyond the ability to correctly model and interpret near wake pressures and slipstream separation locations, the new methodology allows experiments to be conducted with diatomic gases (air or nitrogen, gamma equal 1.4) at much lower stagnation pressures as would be required for propellants of lower specific heat ratios.