To the problem of determining the centre of pressure of liquid on hard surfaces

Abstract

Equations for determining the position of the centre of liquid pressure over the flat hard surfaces have been
given. Cases when there exists excessive pressure or vacuum over free liquid surface are considered. The research has been conducted on the basis of the well known in mechanics Varignon’s theorem. The results have been compared taking into account such term as piezometric surface. The obtained equations can be used in testing the stability and reliability of hydraulic structures and equipment. It has been shown that such research is conducted provided that the sum of the moments of active forces equals to zero. The center of liquid pressure on the flat hard surface has been proved to be indispensable, as the moment of resultant and hydraulic force depends on the location of the center of pressure. Given equations allow us to determine the location of the application point of resulting hydraulic force according to the height of the flat surface wet section accounting for excessive pressure or vacuum over the free liquid surface. Concerning the location of the pressure center horizontally it is situated on the surface symmetry axis.