Abstract
Computational Fluid Dynamics (CFD) is a well-known tool for predicting and analyzing performance in a variety of engineering branches, including turbomachinery, allowing engineers to partially replace physical experiments with their virtual analog. Nevertheless, numerical analysis should be used carefully regarding possible deviation between simulated and experimental results due to multiple reasons (including but not limited to applied simplifications in the numerical model). These deviations usually have their minima close to the Best Efficiency Point (BEP). The paper deals with analyzing the outcome of steady-state simulations for a radial pump at strong part load and shut-off conditions by switching between three simulation types (steady-state with mixing plane, steady-state with frozen rotor, transient with sliding mesh). A comparison of velocity profiles on the interface surfaces is made, showing how the chosen interface model affects the structures being formed at part load conditions. These effects show particular impact on performance parameters (first of all, head production), which is discussed in the paper. The information provided could be helpful for adjusting the simulation parameters and finding an appropriate compromise between simulation reliability and demand for computational time thereby.
Highlights
Computational Fluid Dynamics (CFD) methods are widely used for predicting performance in rotordynamic machinery
Even though computational resources are getting more available in the last years, particular simplifications are still broadly used nowadays in order to achieve feasible results in a practically suitable time
Velocity distribution in volute is shown on figure 6, where velocities are plotted for a plane located in the middle of the impeller outlet width, based on the results of transient simulation
Summary
Computational Fluid Dynamics (CFD) methods are widely used for predicting performance in rotordynamic machinery. Feasible results could be achieved in the case of small pitch changes, which is usually the case for turbomachines with high amount of blades. Such method is hardly applicable for rotordynamic pumps, which are usually designed with 2 to 8 blades (depending on specific speed) for the impeller. Having a volute as diffusing element introduces additional limitation for scaling the data, making the pitch change even more significant
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