Multiobjective optimization of the semi-open impeller in a centrifugal pump by a multilevel method

The complete optimization task for the case of the semi-open impeller with straight blades requires description of its geometry by means of, at least, eighteen design variables. In the case of constant meridional cross-section, required are at least eight design variables. Solution of the task with such a great vector of design variables requires much more time. One of the ways to obtain solutions with great variety of design variables is a comprehensive approach to the task including on the partition into minor subtasks. After decomposing the optimization task, one should choose a procedure for solving it. One of such procedures is parametric optimization, which is a two-stage minimization (maximization) method. This optimization is carried out in two levels. On the lower level, the multi-optimization of the decomposed parts of the tasks, depending on design variables, is being held. The solution of the lower level is used in the upper level (coordinating level) to find optimal coordination variables. It has been shown that the result of multilevel optimization and the whole task optimization is the same in limits of accepted accuracy of calculation of the objective functions. Time of the calculation for the multilevel optimization task is over four times shorter than the time of the undecomposed task.