Numerická simulace vtokových vírů

Numerical simulation of pump-intake vortices

conference paper

en

Pump pre-swirl or uneven flow distribution in front of the pump can induce pump-intake vortices. These phenomena result in blockage of the impeller suction space, deterioration of efficiency, drop of head curve and earlier onset of cavitation. Real problematic case, where head curve drop was documented, is simulated using commercial CFD software. Computational simulation was carried out for three flow rates, which correspond to three operating regimes of the vertical pump. The domain consists of the pump sump, pump itself excluding the impeller and the delivery pipe. One-phase approach is applied, because the vortex cores were not filled with air during observation of the real pump operation. Numerical simulation identified two surface vortices and one bottom vortex. Their position and strength depend on the pump flow rate. Paper presents detail analysis of the flow field on the pump intake, discusses influence of the vortices on pump operation and suggests possible actions that should be taken to suppress the intake vortices.

Předrotace na vstupu do čerpadla nebo nerovnoměrné rozložení proudového pole před čerpadlem může vyvolat vtokové víry. Tento jev způsobuje ucpání sacího prostoru, zhoršení účinnosti, stržení křivky měrné energie nebo i dřívější vznik kavitace. Skutečný případ, kdy došlo ke stržení křivky měrné energie je v předloženém článku studován za pomoci CFD. Je simulována čerpadlová jímka, skříň čerapdla bez oběžného kola a výtlačné potrubí. Simulace je uvažována jako jednofázová, protože i u skutečného čerpadla nedocházelo k přisávání vzduchu. Článek prezentuje výsledky numerické analýzy, ktereá detekovala dva hladinové víry a jeden vír dnový. Závěrem jsou diskutovány opatření pro potlačení vírů.

Pump pre-swirl or uneven flow distribution in front of the pump can induce pump-intake vortices. These phenomena result in blockage of the impeller suction space, deterioration of efficiency, drop of head curve and earlier onset of cavitation. Real problematic case, where head curve drop was documented, is simulated using commercial CFD software. Computational simulation was carried out for three flow rates, which correspond to three operating regimes of the vertical pump. The domain consists of the pump sump, pump itself excluding the impeller and the delivery pipe. One-phase approach is applied, because the vortex cores were not filled with air during observation of the real pump operation. Numerical simulation identified two surface vortices and one bottom vortex. Their position and strength depend on the pump flow rate. Paper presents detail analysis of the flow field on the pump intake, discusses influence of the vortices on pump operation and suggests possible actions that should be taken to suppress the intake vortices.

čerpadlo, vtokový vír, čerpadlová jímka, CFD

pump, instake vortex, pump well, CFD

2015

06.05.2015

EDP Sciences

2100-014X

EPJ Web of Conferences

92

5

1–6

6