Swirl flow in conical diffusers

Abstract

This paper comprises complex experimental investigations of the turbulent swirl flow in three conical diffusers (various diffuser angles). The incompressible swirl flow field is induced by the axial fan runner, which is set in the initial part of the straight pipe section followed by a conical diffuser. The average values of pressure and fluid velocity are determined using classical probes measuring the profiles of total and static pressure, as well as flow angle, i.e. profiles of the average circumferential and axial velocity components at different sections along the conical diffuser, for different regimes. Ratio of swirl flow loss coefficients and loss coefficients in pure axial flow, for tree conical diffusers is determined. With LDA system specific velocity components in certain sections of a diffuser were measured and statistical properties of generated turbulence were calculated. Comparison of the results of measurements of the average velocity of classical probes and LDA system is also shown.