Pumping liquids from a reservoir with a free surface, like basins or waterbodies, may lead to gas entrainment via hollow vortices, e.g. when the intake pipe socket is not sufficiently covered by liquid. Gas within the pump leads to a reduction of conveying capacity up to the point of collapse or damage of the pump. When the pump is part of a safety system, e.g. as an emergency cooling in a power plant, this must be avoided. Within the BMBF funded project SAVE the behaviour of an industrial pump operating in two-phase mode has been extensively analysed concerning different gas volume rates and gas patterns. Furthermore, arrangements have been analysed that can either avoid gas intake or convey the gas phase outside the pump. Gamma-ray CT was used to disclose the gas distribution in the impeller of the pump during rotation.
In another project together with TU Dresden also the interaction between gas phase and the impeller of a 200 mm axial pump was visualised using gamma-ray CT, which gave a fundamental insight into the collection of gas behind impeller blades for this type of pump.
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Application of gamma-ray computed tomography for the analysis of gas holdup distributions in centrifugal pumps
Flow Measurement and Instrumentation 46, pp. 262-267, 2015. [doi:10.1016/j.flowmeasinst.2015.06.001]
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Validation of high-resolution gamma-ray computed tomography for quantitative gas holdup measurements in centrifugal pumps
Measurement Science and Technology 26/9, pp.1-12, 2015, [doi:10.1088/0957-0233/26/9/095304]
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An experimental study on the gas entrainment in horizontally and vertically installed centrifugal pumps
Journal of Fluids Engineering 138 (09130) pp. 1-9, 2016. [doi: 10.1115/1.4033029]
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Experimental investigations on a common centrifugal pump operating under gas entrainment conditions
Nuclear Engineering and Design 316, pp.1–8, 2017. [doi: 10.1016/j.nucengdes.2017.02.035]
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Time Resolving Gamma-Tomography for Periodically Changing Gas Fraction Fields
Flow Measurement and Instrumentation 14, pp. 119-125, 2003. [doi:10.1016/S0955-5986(03)00010-4]