000139267 001__ 139267
000139267 005__ 20190812205330.0
000139267 0247_ $$2doi$$a10.1115/FEDSM2007-37550
000139267 02470 $$2ISI$$a000254289800149
000139267 037__ $$aCONF
000139267 245__ $$aUnsteady Numerical Simulations of the Flow Related to the Unstable Energy-Discharge Characteristic of a Medium Specific Speed Double Suction Pump
000139267 269__ $$a2007
000139267 260__ $$c2007
000139267 336__ $$aConference Papers
000139267 520__ $$aRegions of positive slope in the pressure-discharge characteristics can result in a reduction or even lack of damping of system instabilities. They are therefore one of the major concerns in design and operation of centrifugal pumps as they are limiting the admissible operating range. The considered preliminary hydraulic design of an industrial double suction pump of medium specific speed n = 0.410 (0.205 per impeller side) shows a marked saddle in the energydischarge characteristic associated to a sudden drop of efficiency versus discharge at part load. Unsteady RANS type flow simulations are performed using hexahedral meshes with 2.5 million nodes to model the inlet casing, the shrouded double sided impeller with 2 x 7 blades, the diffuser with 12 blades and the volute. In unsteady solution monitoring, low frequency (below blade passing frequencies) phenomena are noticed. Therefore, simulation times of up to 10 impeller revolutions at each flow rate are requested to achieve statistically steady behavior of the flow judged on global performance numbers and circumferential flow rate distribution. The numerical simulations emphasize a drop in the characteristic, though at a lower flow rate than found on the test rig. It is shown to be associated to a one-sided separation in the diffuser, further leading to an unbalanced flow rate distribution of about 10% of flow rate between both sides of the impeller. There is a region of hysteresis, where both configurations with balanced and unbalanced flow rate distributions can be obtained for the same global flow rate. The asymmetric flow distribution leads to asymmetric velocity profiles at the impeller-diffuser interface which results in a strongly vortical flow in the diffuser channels, where an important amount of energy is dissipated in regions of increased viscous and turbulent shear.
000139267 700__ $$aBraun, Olivier
000139267 700__ $$0241012$$g104417$$aAvellan, François
000139267 700__ $$0243999$$g105022$$aDupont, Philippe
000139267 7112_ $$dJuly 30–August 2, 2007$$cSan Diego, California, USA$$aASME/JSME 2007 5th Joint Fluids Engineering Conference
000139267 773__ $$j2, part A-B, Fora$$tASME Conf. Proc. FEDSM2007$$q971-977
000139267 8564_ $$zn/a$$uhttps://infoscience.epfl.ch/record/139267/files/FEDSM2007-37550.pdf$$s825084
000139267 909C0 $$xU10309$$pLMH$$0252135
000139267 909CO $$ooai:infoscience.tind.io:139267$$qGLOBAL_SET$$pconf$$pSTI
000139267 917Z8 $$x148230
000139267 937__ $$aLMH-CONF-2009-004
000139267 973__ $$rREVIEWED$$sPUBLISHED$$aEPFL
000139267 980__ $$aCONF