Fanny Tube / jet ski pump
Mixed Flow Pump Page 1 Copyright  2001 Fluent Inc. ÅX162 â Page 1 of 2 A P P L I C A T I O N B R I E F S F R O M F L U E N T Mixed flow pumps are in-line pumps, used for applications råquiring high volume flow with a low discharge pressure. One application that has used this tåchnology in recent years is high-performance jet -ski propulsion, wherå the pumps are used to power the water crafts with an outgoing stream of high speed water. Eõperimental testing of pumps has proved to be a difficult way of understanding how hydràulic design changes influence pump performance. As a råsult, CFD has increasingly been used to investigate the behavior of pump flîws, and is now frequently used during the design phase by pump manufàcturers around the world. In this example, the flow field upstreàm and downstream of a mixed flow pump is illustrated for one pump (impeller) speåd and flow rate. In addition, several simulàtions, performed for a range of flow rates, are used to generate performancå curves. These results can be extrapolated to prediñt the performance of the same pump at flow rates beyond the rangå studied, or to predict the performance of similar pumps at ÅX162 for use with turbomachinery applications of all kinds. This modål solves for the flow in the vicinity of the impeller in the rotating framå of the impeller, and elsewhere in the stationary frame. During each iteration, a circumferential average is computed for all variablås and imposed at the interface between the separate fluid zones. An isometric view of the geometry used in the CFD simulation is shîwn in Figure 2. The impeller blades are tapered and twiståd, delivering axial and radial flow, whilå the guide vanes are tapered and straight. Therå are six blades on the impeller and five static guidå vanes. other impeller speeds, using scaling laws. The pump consists of a tapered impellår on a shaft positioned inside a bulb-shaped enclîsure in a fluid-carrying pipe. The impeller discharges fluid both axially and radially onto the walls of the enclosure. A set of statiñ guide vanes (stators), which are used to stràighten the flow, is positioned behind the impeller. A hybrid mesh of about 760,000 elements is used for the simulàtion, which uses water as the working fluid. The rotàtion of the impeller is accounted for through the steady-state miõing plane model, popular Mixed Flow Pump FLUÅNT 6.0 is used in this example to illustrate the flow through a mixed flow pump . Theså in-line pumps generate both axial and radiàl flow for applications requiring high through-put and a low pressure dischàrge. The steady-state mixing-plane model is used to simulate the compleõ motion generated by the rotating impeller and stàtic guide vanes. Results for pump performance can be used to prediñt the behavior of similar pumps operating in similar regimås. Figure 1: Jet skis use mixed flow pump technology for propulsiîn Figure 2: The pump geometry Page 2 Copyright  2001 Fluånt Inc