Numerical Study On Influence Of Volute Casing Inlet Width On Centrifugal Pump Performance

Centrifugal pump has two important flow components that are impeller and volutecasing basically which together determine the centrifugal pump performance. As animportant flow components within a centrifugal pump volute casing plays an important roleof diversion and rise pressure, the design of which has significant influence on theperformance of pump. But a long time, people tend to focus on the research on the impeller,largely ignoring volute casing and the match relationship between impeller and spiral case.That can result in that the single impeller performance is often very excellent, and onceworking with volute casing, various performance indicators will be dropped substantiallywith the stability conditions such as the vibration and noise. Therefore, to greatly improvethe various performance indicators of centrifugal pump must solve the problem of matchingbetween impeller and diffuser.In this paper the matching relation between spiral case with several width and impellerwas studied. Firstly in this paper hydraulic design about the volute of centrifugal pump andthe calculation method of the volute trapezoid section are introduced in detail, and then withthis method, basis on the prototype pump volute and ensure sectional area unchanged,redesigned the two volute with import width designed to be different from prototype pumpeach other, and combination with respectively prototype pump impeller as the model pumpresearched in this paper. Using FLUENT software flow in the centrifugal pump, thethree-dimensional constant and unsteady numerical simulation, the calculation results a morecomprehensive reveals three model under the condition of the full port in the static pressureand velocity distributions, analyzes the width of the spiral case was import centrifugal pumpand diffuser internal pressure pulsation characteristics of the influence, and get the followingmain conclusions:(1) Import width of the volute casing influence on the outside characteristics ofcentrifugal pump. Three of the model prediction results show that both efficiency and head ofpumps decrease a little bit with the increase of the spiral case imported width.(2) Import width of the volute casing influence on distribution of the static pressure andspeed field. For the same flow the high pressure area near the wall of volute casing increaseswith imported width of the volute casing reducing, which is very significant from the eighthsection to export of diffusion section; along with the increase of imported width of the volute casing, the speed at the tongue and the export of blade is reduced. The flow field at diffuserof the volute casing are obviously affected by the import width of volute casing and with theincrease of imported width of the volute casing, the area of low speed within diffuser spreadof volute casing expand.(3) Import width of the volute casing influences on the distribution of the absolute speedin section of volute casing. The imported width of the spiral case is greater, inlet velocityvalue is smaller, the velocity distribution to spread the wall, the scope of the vortex is biggeralso.(4) Import width of the volute casing influences on the distribution of static pressure andabsolute speed at the volute casing entrance. Overall each flow with the increase of importedwidth of the volute casing, the static pressure at the volute casing entrance slightly increases,but the pressure fluctuations reduce. The flow conditions, and imported width of the volutecasing influence more obviously on the radial velocity at the tongue, and the radial velocityis reduced with the imports width volute casing increases.(5) Import width of the volute casing influences on the pressure pulsation characteristicswithin the volute casing. Near the tongue the range and intensity of pressure fluctuation arebigger, volute tongue in the distance runner closer monitoring stations, the amplitude and thegreater pressure pulsation strength. The import of the width of the spiral case was to changeand entrance wall volute pressure fluctuation characteristics have certain effect, in generalthe spiral case was imported wide, pressure pulsation of the smaller range.