Abstract
Twin-screw pumps employ clearances between both screws and screw rotors and housing, which cause backflow as function of pressure differential. Reduction of this flow can be reached by proper geometry design. For the experimental investigation, the scaled model 1:2 of the screws section was produced with trapezoidal tooth profile in two modifications differing in tooth width and pitch. Measurement of flow characteristics of non-rotating twin-screw model was carried out for validation and possible corrections of the 3D CFD model. The testing was done with non-Newtonian liquid met in the food industry and additionally also with water. Experimental data were partly compared with results obtained from numerical simulations.
Highlights
Twin-screw pumps provide good operating efficiencies in comparison with centrifugal pumps when handling viscous liquids such as those met in food industry
Numerical CFD analysis presented in [1] focused on investigation of the influence of the screw geometry, clearances and non-Newtonian behaviour of the fluid
In order to investigate the effects of the different clearance size on the mass flow rate, the circumferential clearance was varied by 0.05 mm and investigated separately for both geometries
Summary
Twin-screw pumps provide good operating efficiencies in comparison with centrifugal pumps when handling viscous liquids such as those met in food industry. Rheological characteristics of the pumped materials significantly influence the performance of a twin-screw pump and are important in the specification of screws design parameters. Numerical CFD analysis presented in [1] focused on investigation of the influence of the screw geometry, clearances and non-Newtonian behaviour of the fluid. Computational modelling of the non-Newtonian liquid flow through the simplified model of a pair of screws showed significant penetrations of masses through clearances from higher pressure to lower pressure, both for screw thread geometries with minimized and enlarged clearances. This penetrations cause reduction in the volumetric efficiency of the screw pump. In 2019 in agreement with HYDROSYSTEM project a.s. it was decided to continue this investigation and prepare physical experiment for validation and correction of the numerical model
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