In this study we introduce pump design work in which two vertical diffuser pumps are designed by using computational fluid dynamics and vane shape optimization. The first pump is a submergible pump having the specific speed of 300(m3/min-m-rpm). The effects of vane shape change on pump performance have been studied for this pump. Some effects of impeller inlet profile and diffuser blade angle are shown. Since this pump has very high head, the impeller exit angle of the first design model has been increased to get the specified head. This modification induces flow separation on the impeller blade. Blade angle distribution has been modified to eliminate the flow separation so that pump efficiency is maintained as high as in the base model. The second pump is a CWP for power plants having specific speed of 330. Blade shape is designed by using fractional factorial design method. The main effects and the interactions of design parameters are investigated. Impeller inlet diameter is increased to get better NPSH required performance. Flow analysis shows that the design model has higher efficiency and better cavitation performance than the existing model.

In order to obtain sufficient towing force, tug boats are usually equipped with high powered engines and special thrusters such as azimuth thrusters. The hydraulic design of a ducted azimuth thruster was carried out for a 2 MW-class tug boat by using CFD. Here, the azimuth thruster consists of a fixed-pitch screw propeller, a duct, a gear casing and a strut. To design the duct propeller, the effects of design parameters of a screw propeller and a nozzle on thruster performance were evaluated. The proper section shape of the strut is also important because it can largely affect inflow velocity distribution on the propeller. The model of the designed azimuth thruster was manufactured with a scale ratio of 10. Propeller open water and cavitation observation tests were carried out to confirm the performance of the design model.

In this paper, a study of performance improvement for a centrifugal vertical pump having specific speed of 330 is introduced. The existing model has high efficiency but needs better NPSH required performance. Such that new pump model is designed to obtain larger suction specific speed. 6 design parameters considered to affect pump performance are selected for impeller design. Key design parameters are investigated using by design of experiments and CFD, and impeller inlet diameter is increased to get better suction performance. The amount of inlet diameter increase is determined by using cavitation analysis. The results show that new design model has higher efficiency and better NPSH required performance than the existing model.