Study On Theory Of Turbulent Boundary Layer On Centrifugal Pump Impeller And Its Application

Pump is a kind of old and extensively-used general machinery, it plays an important role in national economy such as in urban water supply system, power plant, mining industry and other industries. Many research workers in institutes and universities are engaged in researches on laws of internal flows of pump and its design so as to raise efficiency. Because the intern flows of pumps are complex, some of researchers try to find a kind of way to describe the laws of the internal flow of impeller. Dr. Zhu Yucai first presented the theory of boundary layer of centrifugal pump and derived the vane shape equation. Based on the theory and analysis of references abroad and home on centrifugal pump, the thesis creates a mathematic model of turbulent boundary layer of centrifugal pump. Firstly, based on N-S equation, the momentum differential equation(contained centrifugal force) is derived by simplification in boundary layer and then integrates the differential equation over the thickness of the boundary layer, the momentum integral equation is deduced. The dimensionless centrifugal factor is introduced, then the solution of the momentum integral equation is obtained. The dimensionless group is introduced to determined separation of boundary layer. Based on the theory of boundary layer and analysis of the velocity field of main flow, the thesis also derives the vane shape equation. In the equation,(angle of pump vane)is variable parameter, (velocity coefficient)is introduced as medium factor, which connects the theory of boundary layer with the Eular theory. It provides a valuable reference for the designation of vane of pump. Finally the thesis uses the theory to design the pump vane and then tests results though the experiment. The experiment shows that by changing the velocity coefficient , the separation of boundary layer on pump vane can be controlled, and the performance of pump is improved and its hydraulic efficiency.The creative points of the thesis are as follows:(1) The thesis establishes turbulence boundary layer equation that contains centrifugal force in flow field of two-dimension boundary layer of centrifugal pump and gives its solution.(2) In application of the theory, the thesis considers the influence of the viscosity in boundary layer on the performance of centrifugal pump(efficiency, dynamic property, head, etc) and verifies the results through experiment.