Experimental investigation of swirl flow in a rotating lid-driven cavity
Igor V. Naumov
Institute of Thermophysics, Novosibirsk
Abstract:
A brief review of experimental results accomplished at DTU about swirl flows in a rotating cavity is presented. It consists of different techniques including tagged particles for Lagrangian visualizations, particle image velocimetry (PIV) technique and laser Doppler anemometry (LDA). The aim is to establish a new experimental approach with simultaneous use of PIV and LDA for diagnostics of swirl flow with vortex breakdown and three-dimensional flow instability.
A detailed mapping of the transition scenario from steady and axisymmetric flow to unsteady and three-dimensional flow is investigated for aspect ratios 1.0 £ h £ 5.5. A range of different modes is detected and critical Reynolds numbers and associated frequencies are identified. The onset of three-dimensional flow behaviour is measured by combining the high spatial resolution of PIV and the temporal accuracy of LDA. The boundary of the transition to unsteady flow regimes, which arises as a result of the equilibrium rotation of self-organized vortex multiplets (triplet, double triplet, double doublet, and quadruplet), has been experimentally determined for aspect ratios 3.3 £ h £ 5.5.