Comprehensive Study Of Unsteady Pressure Pulsations Induced By The Spiral Vortex Structure In A Conical Diffuser

Abstract

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 (source of strong swirling flow) and the conical diffuser (equipped with the series of pressure transducers). The experimental measurements are focused on complex pressure measurements in order to distinguish between synchronous and asynchronous pulsations induced by the vortex structure and examine their changes in relation to the flow rate. The numerical simulations are carried out to visualize vortex shape and compare computed pressure fields with the experimental ones. The open source CFD software OpenFOAM employing realizable k- turbulence model is used for the numerical simulations. Agreements between numerical end experimental results are discussed.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 (source of strong swirling flow) and the conical diffuser (equipped with the series of pressure transducers). The experimental measurements are focused on complex pressure measurements in order to distinguish between synchronous and asynchronous pulsations induced by the vortex structure and examine their changes in relation to the flow rate. The numerical simulations are carried out to visualize vortex shape and compare computed pressure fields with the experimental ones. The open source CFD software OpenFOAM employing realizable k- turbulence model is used for the numerical simulations. Agreements between numerical end experimental results are discussed.