Experimental investigations of the turbulent swirl flow in straight conical diffusers with various angles

Abstract

Results of experimental investigations of the turbulent swirl flow in three straight conical diffusers with various diffuser total angles are presented in this paper. All three diffusers have the inlet diameter 0.4 m and total divergence angles 8.6?, 10.5?, and 12.6?. The incompressible swirl flow field is generated by the axial fan impeller, and for each diffuser several regimes were achieved by changing rotation number. Original classical probes were used for measurements. The distributions of the average main swirl flow characteristics along the diffuser are shown. Distributions of the inlet Boussinesq number, outlet Coriolis coefficient, ratio of the swirl and completely axial flow loss coefficients at conical diffuser on the inlet swirl flow parameter are also presented.

Integral and statistical characteristics of the turbulent swirl flow in a straight conical diffuser

“…The diffuser has an inlet diameter D 0 = 0.4 m, an outlet diameter D 9 = 0.67 m, length L = 1.8 m and an angle α dif = 8.6 • . Velocity fields were measured at cross-section number 2 defined in [7,8] as z 2 = 0.2 m, or as z 2 /R 0 = 1 and z 2 /L = 0.22, along one measuring radius R 2 with 21 measuring points. The measurements were performed for four regimes, with different booster fan rotation speeds, constant AP 400 fan rotation speed (n = 1000 min −1 ) and the open flow regulator.…”

“…The influence of the Reynolds number on integral and statistical properties of the generated turbulent swirl flow is studied in [5,6]. The results of experimental investigations of the turbulent swirl flow in three straight conical diffusers with various diffuser total angles (8.6 • , 10.5 • and 12.6 • ) are presented in [7,8]. The original classical probes were used in the investigation presented in [8].…”

The Influence of Supply Channel Design on the Gas-Dynamic Structure of Air Flow in a Vertical Conical Diffuser

“…There are comprehensive studies of the gas-dynamic features of complex flows (swirl flows, spiral vortices, vortex cores, etc.) in conical diffusers and their possible application in various fields [28][29][30][31][32][33]. For example, M. Tsoy and colleagues studied in detail the development and destruction of spiral vortices in conical diffusers with different cone expansion angles [28].…”

“…Similar studies were carried out by X. Zhou and colleagues in relation to vortex cores and their influence on flow characteristics in CDs. A large number of researchers are focused on studying swirl flows in conical diffusers of various configurations [30][31][32][33]. This can be explained by the fact that swirl flows help intensify heat transfer, improve the mixing of various media, and distribute the flow throughout the entire volume of the diffuser.…”

“…Thus, Z. Liu and co-authors studied the specific problem of the influence of the expansion angle of the pressure vessel on the vortex core of a swirl flow with a PIV measuring system [30]. D. B. Ilić and colleagues studied the distribution of the average gas-dynamic behaviour of a swirl flow along a diffuser with different expansion angles [31]. Research has confirmed that introducing moderate inlet swirl reduces the likelihood of separation in wide-angle conical diffusers.…”