Searching stochastic method of the submersible electric pump flow part optimal shape

BACKGROUND: Modern approaches based on numerical optimization methods are used in development of pumps in order to achieve the high level of efficiency. These methods with use of parametrical models of flow sections of pumps help to find either global or local extremum of an objective function and to obtain the optimal geometric shape of the flow section. The study object is a dewatering electric submersible pump with cantilever working wheel arrangement used in shipbuilding industry.

AIM: Improvement of energy indicators of the flow section of the high-speed electric submersible pump at the nominal operation mode by means of calculation with the use of the stochastic algorithm of search of the global extremum of an objective function that is pump hydraulic efficiency.

METHODS: Search of the optimal shape if the flow section was conducted with the use of mathematical modelling of three-dimensional flow of a viscous fluid in the computational region of the studied object. The parametrical model of the flow section includes nine geometric variables (four variables for a working wheel, five variables for an outlet element) and their variation ranges. The chosen algorithm of search of the global extremum of the objective function is the Latin hypercube method which ensure uniform distribution of geometric variables in the search space. According to the compiled matrix of experiments with various combinations of parameters, direct fluid dynamics simulations of flow in the flow section were performed.

RESULTS: Simulation results showed that it was managed to improve the pump hydraulic efficiency by 7% in comparison with the initial flow section. According to the velocity field analysis, energy indicators improvement was achieved mainly by increasing the width of channels between an electric motor and a housing, leading to velocities decreasing and lowering the level of hydraulic losses in the outlet element of the flow section of the pump.

CONCLUSONS: The Latin hypercube method proved its effectiveness in search of the global extremum of the pump hydraulic efficiency. The obtained result can be used in further as the initial point in search of the local extremum with direct methods in the area around the found global extremum of the objective function.