A Numerical Simulation on Underwater Convection Phenomena of a Floating Vertical Axial Pump

摘要

The underwater convection phenomena of a floating vertical axial pump are visualized by the numerical simulation. In this report, the following contents were summarized; (1) comparison of the velocity distribution on the measured value and the simulation for confirmation of the accuracy, (2) influence on the flow according to attachment of the extension duct, and (3) consideration of the available region of the convection flow by the pump. The flow rate which was estimated by the velocity distribution of the simulation was able to predict the measured values in near field with less than 12% accuracy. The calculation accuracy of the flow was deteriorated in the reverse drive condition since the velocity distribution of the jet flow that flowed from the duct could not be given to the boundary condition. In the normal drive condition, the influence on the flow according to attaching the extension duct was small. The pump was able to supply the kinetic energy until the convection region on the target performance in the normal driving condition. On the other hand, in the reverse drive condition, it is predicted that the convection region is reduced until approximately 1/3 of the target performance because of the friction loss caused by the wall of bottom of the water.