Accession Number : AD0484779

Title :   THE EFFECTS OF NONSTEADY FLOW ON THE PRESSURE DISTRIBUTION ABOUT A CIRCULAR CYLINDER,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Murphy, John Cowden

Report Date : MAY 1966

Pagination or Media Count : 84

Abstract : Nonsteady flow is an inherent problem in all fields of aerodynamics. The present work is an experimental investigation of the effects of large scale flow disturbances on the pressure distribution about a transverse circular cylinder. The nonsteady flow in this study was obtained by use of a rotating shutter valve to superimpose a sinusoidally varying velocity component on a mean stream. The frequency of the velocity oscillation covers the range of from 2.0 to 90.0 cycles per second, with amplitudes ranging from 10 to 40 percent of the mean freestream velocity. Both the mean pressure distributions and the instantaneous surface pressure variations were studied for flows in the subcritical and transcritical Reynolds number ranges. Results show that the mean surface pressure is affected most in the high transcritical Reynolds number range at low oscillation frequencies. Here the effect is a reduction of the critical Reynolds number. An effect of low oscillation frequencies on the instantaneous pressure variations consists of a phase shift between the freestream velocity and the velocity near the wall. At high oscillation frequencies this phase shift does not occur, however random fluctuations in the surface pressure are introduced at all angular positions on the cylinder surface. (Author)

Descriptors :   (*CYLINDRICAL BODIES, SUBSONIC CHARACTERISTICS), OSCILLATION, SUBSONIC FLOW, PRESSURE, DISTRIBUTION, VELOCITY, BOUNDARY LAYER TRANSITION, REYNOLDS NUMBER, TURBULENCE, AERODYNAMIC LOADING, LAMINAR FLOW, FREQUENCY, BOUNDARY LAYER, FLOW SEPARATION, STAGNATION POINT, WIND TUNNEL MODELS, MODEL TESTS, PERFORMANCE(ENGINEERING), EXPERIMENTAL DATA.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE