Research On Flow Passage Design In Waterjet Pump

As a new type of ship propulsion, the water jet propulsion device is gradually expanding its application areas. Especially in the high-performance ships, because of the enormous predominance, it has been widely used. In the future field of high-speed boats, the water jet propulsion device will develop toward the direction of high power and high efficiency. As the core component of the water jet propulsion device, the performance research of pump is extremely important.Based on the two families of stream line surfaces theory, using FORTRAN language, the quasi-three-dimensional inverse problem program can be designed. The program can be considered universal. For this article, according the design speed and power conditions, the procedure can be achieved by modifying the general program. Using the DATA files generated by the program, the three-dimensional model of water jet pump was made. FLUENT was used to simulate the flow inside with different shapes of flow passage finally. This paper designed five types of the water pump flow shapes. ModelⅠsatisfied the ratio of inner diameter and outer diameter for inlet keeping 0.19; ModelⅡsatisfied the ratio of inner diameter and outer diameter for inlet keeping 0.25. ModelⅢsatisfied the ratio of inner diameter and outer diameter for inlet keeping 0.30; Based on modelⅡ, at the inlet of the impeller, ModelⅣchanged the sidelines shape of the hub and case to increase the centrifugal angle; Compared with modelⅣ, modelⅤjust increased the centrifugal angle appropriate properly; For each model, seven to eight operating points were selected to calculate. In these conditions, the low flow condition, design conditions and high flow condition were selected as typical working conditions. For different flow conditions of the first three models, the flow fields were compared and analyzed, including pressure and velocity fields. In addition, for the five models, calculate the mass flow, head, power, efficiency and cavitation area of each operating point and analyze the external characteristic and cavitation performance.After completion of the above work, according to the analysis results, the paper also studied how to select the models for the design operating point and calculated the models with different speeds. Since cavitation is an important factor for the pump performance, the model which had excellent cavitation performance was selected. After that, the paper analyzed the variation tendency of the flow, head, power, efficiency, and cavitation area with different speeds. In this paper, the cavitation area was relative large for the absence of blade cavitation optimization. However, the paper could give the optimal flow passage shape. So we can select the model according to different design requirements for the pump. It will provide the foundations for the experiment of the water pump.