The external characteristics and inner flow research of rim-driven thruster

Abstract

In order to have a more comprehensive grasp of the performance of the rim-driven thruster, the external characteristics are studied by experiment and carry out numerical simulation to study inner flow characteristics. The test results for the rim-driven thruster find that the head curve had a hump shape. The head is the largest while the flow rate Q = 600 m3/h. The numerical simulation is carried out to reveal the cause of the hump of head. The results show that large-scale backflows gradually appear near the wall in front of the impeller inlet, the central area of the impeller outlet, and the two sides of the central low-pressure zone with the reducing of the flow rate, which can cause a large flow loss and result in a drop in head. The discrepancy between the pressure surface and the suction surface of blade decreases rapidly in the range of r/ R = 0.2–0.5, which is another major factor leading to the drop in head under small-flow conditions. Structurally, there is no blade in the impeller center and there are the large backflows in the middle of impeller, which causes much volume loss and is a main cause of the decreasing of head under small flow rate.