Accession Number : AD0856476

Title :   Consideration of Velocity Peaks in Different Transient Flows,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OH

Personal Author(s) : Savulescu, St. N.

Report Date : 04 DEC 1968

Pagination or Media Count : 23

Abstract : The article presents the results of an experimental study of sudden velocity peaks in the transition region of boundary-layer flows. The aim of the investigation was to demonstrate the existence of velocity peaks (spikes) in transition boundary-layer flows other than that on a flat plate, by using hot-wire techniques. By realizing special experimental conditions (low velocity, perturbation of outer flow), velocity peaks were obtained in the following flows: (1) boundary-layer flow with pressure gradient on an airfoil; (2) at the entrance of a channel; and (3) in the wake of certain symmetric and asymmetric bodies. Experiments were carried out in a low-turbulence wind tunnel at flow velocities from 0.8 to 6 m/sec with perturbation produced by obstacles, low-intensity jets, etc). Photographic recordings of the characteristic velocity spikes in various flows are presented. Analyses of physical and theoretical interpretations of instability show that the mechanism of the appearance of these spikes in the flows considered differs somewhat from that known in the case of a boundary layer on a flat plate. (Author)

Descriptors :   (*BOUNDARY LAYER TRANSITION, VELOCITY), PRESSURE, AIRFOILS, WAKE, STABILITY, BOUNDARY LAYER, TURBULENCE, RUMANIA.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE