Study On The Optimum Hydraulic Design Of The Elbow Inlet Conduit

The inlet conduit which connects the fore-bay and the pump is an important part of a pump system. The function of the inlet conduit is to adjust the flow patterns and to satisfy the requirements of hydraulic design conditions of the impeller. Bad flow patterns in the inlet conduit will lead to dropping flow and swirl with the results of uneven pressure distribution on the blades, the increase of hydraulic loss and the decrease of efficiency, even threat the safe operation of the pumping station. In order to ensure that the pumping station operate safely and efficiently, studying the influence of the inlet conduit on the pump system has importantly theoretical significances and practical values.In this paper, the Navier-Stokers fundamental equations and the k—ε turbulence model are used to simulate the elbow inlet conduit. The major contents include:(1)The elbow inlet conduits with pump and without pump are numerically simulated respectively to compare the influences of the impeller chamber on the hydraulic performances of the inlet conduit. The conclusions indicate that the impeller chamber makes a certain difference to the axial velocity distribution evenness and the drift angle at the outlet section of the elbow inlet conduit, and the hydraulic loss of the inlet conduit in the pump system is slightly larger than that of the inlet conduit without pump. This relationship between the hydraulic loss and the flow are also studied by numerical simulation method, the research result indicates that the relationship obeys the quadratic curve.(2)The influence of the lengths of the division pier on the hydraulic performance is studied by numerical simulation method, the computational results show that with the increase of the length of the division pier, the axial velocity distribution evenness increases before it reduces, the drift angle of the flow decreases and the head loss of the conduits increases rapidly.(3)The influences of different geometric parameters on hydraulic performance of the elbow inlet conduit are studied respectively. These geometric parameters include altitude of the elbow inlet conduits, inlet width of the inlet conduit, length of the inlet conduit, height of the elbow, incline angle of bottom line of the inlet conduit. Of all these parameters, the altitude of the elbow inlet conduits has the maximum influence on the hydraulic performance, while the inlet width and the length of the inlet conduit have slight influence on the hydraulic performance, with the increase of the height of the elbow the hydraulic performance of the inlet conduit becomes bad, the increasing of the incline angle of bottom line has slight influence on the hydraulic performance.