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Frequency response of the flow in a radial swirler
Ivan Litvinov,Evgeny Gorelikov,Sergey Shtork 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
We report the results of an experimental study on flow with a precessing vortex core in an isothermal radial swirler burner model. It was shown for the first time that in radial swirler flow, the Strouhal number (the dimensionless precession frequency of the vortex core) is inversely related to the swirl number in the range 0.5 < S < 0.8. A minimum occurs in the precessing vortex core frequency due to the reduced velocity of the helical vortex structure in the axial flow direction and the axial stretching of the helical vortex structure. This finding emphasizes the importance of accounting for the helical geometry of the precessing vortex when predicting the frequency response of burner installations.
Ivan Litvinov,Daniil Suslov,Mikhail Tsoy,Evgeny Gorelikov,Sergey Shtork,Sergey Alekseenko,Kilian Oberleithner 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.4
This paper presents an active method to control the pressure fluctuations induced by the rotating vortex rope (RVR) in a Francis hydro turbine model under part load conditions. The control method is based on the injection of axial or radial jets through a stagnant crown attached to the hydro turbine runner. A wide range of injection strategies are com-pared, and the effectiveness of suppressing pressure fluctuations is analyzed in terms of the spatial distribution of the jets and the flow rate required to suppress the oscillations. The experiments are performed on a fully automated aerody-namic test rig. The pressure fluctuations are quantified using data from the four acoustic sensors placed at a cross sec-tion in the cone of the hydro turbine draft tube. The best suppression of pressure fluctuations is achieved with a radial actuator. At a control flow rate of 2% of the main flow, the pressure fluctuations at the vortex rope frequency are re-duced by 80% in terms of PSD compared to the baseline case without control. The presented control method will be useful for extending the operating range of Francis hydro turbines.