Effect of the diffuser divergence angle on characteristics of turbulent flow with different swirl intensity

The effect of the conical diffuser divergence angle and the flow swirl intensity on the characteristics of turbulent flow and the precessing vortex core that forms within it was studied experimentally. Laser Doppler anemometry was used to analyze the flow. It is shown that the effects associated with changes in the diffuser divergence angle depend significantly on the swirl intensity. With strong swirl, nonmonotonic behavior of the integral swirl number in the far wake of the flow was observed, which is interpreted as a change in flow modes. Increasing the divergence angle intensifies velocity pulsations associated with vortex precession. The obtained results form the basis for validating computational models and optimizing diffusers in power plants.