Accession Number : ADP009008

Title :   On the Formation of Vortex Breakdown Bubbles when Imparting Swirl to Conical Diffusers,

Corporate Author : LIMERICK UNIV (IRELAND)

Personal Author(s) : Frawley, P. ; Thakker, A. ; Gato, L.

Report Date : 23 JUL 1992

Pagination or Media Count : 6

Abstract : To improve the efficiency of wide angled conical diffusers, it is sometimes necessary to impart swirl to the flow. When this swirl is of sufficient severity, a bubble occurs at the axis. This in turn causes blockage and the pressure recovery coefficient drops. This is undesirable. This paper aims at obtaining an understanding of the mechanism of vortex breakdown using Laser Doppler Anemometry, and flow simulation using computational techniques. The diffuser examined has a double conical angle of 40 deg and an area ratio of 4:1. The entry Reynold's number is maintained at 28.4 x 10 3. The parameters being examined are wall pressure distribution axial and tangential velocity profiles and finally kinetic energy of turbulence. The investigation throws light on the mechanics of vortex breakdown and reavels the probability of stalled flow creating the bubble formed at the axis using excess swirl. (Author)

Descriptors :   *DIFFUSERS, *EDDIES(FLUID MECHANICS), BUBBLES, VORTICES, LASER ANEMOMETERS, DOPPLER EFFECT, REYNOLDS NUMBER, IRELAND, PORTUGAL.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE