Numerical and experimental investigation of swirling flow in a conical diffuser

The decelerated swirling flow often breaks down into helical structure which is unstable and causes unsteady velocity and pressure fields. The numerical and experimental investigation of this flow pattern is carried out on the experimental apparatus consisting of the swirl generator (producing a strong swirling flow) and the transparent conical diffuser (where the helical structure can be observed). The open source CFD software OpenFOAM employing realizable k-epsilon turbulence model is used for the numerical simulations. The experimental measurements are focused on LDA measurements of velocity profiles in the diffuser cross-sections. Agreements between numerical end experimental results are discussed.