Accession Number : AD0657013

Title :   A STUDY OF THE CHARACTERISTICS OF TRANSONIC BUFFET PRESSURES ON A LARGE HAMMERHEAD CONFIGURATION,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF TECHNICAL OPERATIONS

Personal Author(s) : Wang,H. E.

Report Date : JUN 1967

Pagination or Media Count : 89

Abstract : The transonic fluctuating pressures over a large hammerhead configuration are investigated. The study examines existing experimental data on other configurations, presents fluid-mechanical arguments, derives a number of concepts and scaling parameters, and finally makes estimates of the fluctuating pressure characteristics for a large hammerhead configuration. The significant findings are as follows: (1) All the fluctuating pressure fields examined seem to indicate a strong influence of a square-wave type of random fluctuation in the low-frequency region; (2) A square-wave type of pressure fluctuation can arise from the random oscillation of the separation point because of stream-wise disturbances or cross-stream disturbances, or from the intermittency of a free boundary; (3) In a narrow range of high subsonic Mach numbers, a periodic modulation of the random pressure fluctuation can arise from shock-wave oscillation. (4) The turbulence field seems to have a 'memory' - a short one at least. (5) The large eddies in the turbulence field apparently dominate the statistical properties; (6) The magnitude of the fluctuating pressures seems to be linearly dependent upon the mixing region or shear layer thickness and can be enhanced by a positive pressure gradient. (7) The unsteadiness of the separation surface behind the backward-facing step of a hammerhead configuration can be visualized as a series of 'teeter-totters' lined up side-by-side around the perimeter and randomly going up-and-down. Thus, a revolving motion of the hammerhead about the flow axis might be induced. (Author)

Descriptors :   (*AERODYNAMIC CONFIGURATIONS, *TRANSONIC CHARACTERISTICS), (*BUFFETING, PRESSURE), (*LAUNCH VEHICLES, TRANSONIC CHARACTERISTICS), MATHEMATICAL PREDICTION, ANALYSIS OF VARIANCE, TURBULENCE, WAKE, FLOW SEPARATION

Subject Categories : Aerodynamics
      Fluid Mechanics
      Ground Support Sys & Facil For Space Vehicles

Distribution Statement : APPROVED FOR PUBLIC RELEASE