Project ForgeAn idealized centrifugal pump (blade outer radius of 50 mm) consumes 2 kW power while running at 3000 rpm. The entry of the liquid into the pump is axial and exit from the pump is radial with respect to the impeller. If the losses are neglected, then the mass flow rate of the liquid through the pump is ___ kg/s (round off to two decimal places).
Explanation
Axial entry means no inlet whirl (Vw1=0). Relative velocity purely radial at exit means the exit whirl velocity equals the blade tip speed, Vw2=U2. So specific work = U2². U2=ωr2=(3000×2π/60)×0.05=15.71 m/s. Specific work=15.71²=246.8 J/kg. ṁ=Power/specific work=2000/246.8≈8.11 kg/s.
Source: GATE ME 2019 Session 2 (Set 3) (2019)
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