Experimental laboratory tests of the pressure drop resulting from the liquid flow through orifices in a rotating disc

Abstract

The article presents experimental laboratory tests aiming to determine the pressure drop occurring as a liquid flows between two spaces through orifices in a rotating disc.A one-dimensional flow model was proposed to establish a dimensionless coefficient of discharge. A dimensional analysis of the problem was conducted for orifices spaced at a certain diameter in a rotating disc, i.e. characterized by a certain transportation velocity. An original testing station as well as a measuring system were designed and installed, and extensive laboratory tests were performed.The dimensional analysis results prove that the coefficient of discharge through orifices in a rotating disc depends on the Strouhal number referred to the orifice. This dependence was confirmed by laboratory tests performed for a water flow. The testing resulted in a formula which proved convenient for engineering applications and which defines the coefficient of discharge through orifices depending on their transportation velocity and the liquid velocity in them. The finding of this dependence is an original result of the testing.The obtained experimental dependence allows a calculation of the pressure drop occurring as the liquid flows through orifices in a rotating disc. A particular instance of the dependence application is designing an axial thrust balancing system based on balancing orifices in impeller pumps, which makes it possible to correctly design the axial thrust balancing system and determine volumetric losses.