Numerical Study And Analysis Of Inner Flow Field Including The Flange Clearance Region Of Kaplan Turbine

This thesis is supported by the National Natural Science Foundation of china (90410019 and 50379044). Kaplan turbine is researched in different paddle blade angle, the guide vane opens and under the unit rotational speed each kind of different operating mode spot. In addition, numerical research of interior mobile for the axis to past the propellor type hydraulic turbine with the wheel rim gap is conducted, and the performance is predicted.First, the three-dimensional model of different guide vane opening and blade angle of Kaplan turbine are established. Grid division of fluid area is conducted.Based on the Navier-Stokes equation and the turbulent flow model, numerical research of interior fluid of Kaplan turbine with the wheel rim gap is conducted. Water flow velocity from outlet of guide vane to runner outlet in small operating condition and the velocity matrix distribution rule is analyzed. On optimum operating condition and in great operating condition, the result indicated that flow channel curve have the certain influence to distribution of the runner leaf blade inlet velocity when the guide vane opening is different. The flow channel curve can change distribution rule of circular velocity and rectangular of the runner blade inlet. The circular velocity decreases and the rectangular increases from hub to flange of wheel. The circular velocity which is close to the flange of wheel is influenced by the flange clearance with obvious fluctuation.Then, through comprehensive and systematically numerical computation to dynamic performance of the Kaplan turbine in different operating condition, pressure distribution of hydraulic turbine leaf blade, the flow field of basin and the streamline distribution of wheel rim are elaborated, and influence of wheel rim gap on dynamic performance of turbine under the different operating mode is analyzed.Finally, based on the flow field computation result, the performance estimate of Kaplan turbine runner is conducted and the comprehensive characteristic diagram of curves is drawn up. The computational results are compared to the empirical datum, which confirms that proposed method of Kaplan turbine runner performance estimation is feasible.The research in this paper provided the basis for further optimizing the design of hydraulic turbine leaf blade and the power plant stable movement.