Method of determining the degree of liquid aeration in a variable capacity displacement pump

Abstract

The Author concludes, that there is a possibility of determining a concrete value of the liquid aeration coefficient ε during the pump operation by finding such value of ε with which the increase ΔM_{Pm|ΔpPi = pn, qPgv} of torque of mechanical losses is proportional to the indicated torque M_{Pi|ΔpPi = pn, qPgv} determined with a fixed value Δp_Pi = cte of increase of pressure in the pump working chambers. The fixed value Δp_Pi assumed in searching the liquid aeration coefficient ε equals to the nominal pump operation pressure pn (Δp_Pi = cte = p_n). The increase ΔM_{Pm|ΔpPi = pn, qPgv} of torque of mechanical losses with a fixed value of Δp_Pi (Δp_Pi = cte) is proportional to the pump geometrical working capacity q_Pgv , therefore: only with taking into account the aeration coefficient ε of liquid displaced by the pump the relation ΔM_{Pm|ΔpPi = pn, qPgv}∼ q_Pgv can be obtained from tests. The method, proposed by the Author, of determining the working liquid aeration coefficient ε, is presented in this paper and has been practically applied for the first time by Jan Koralewski in his investigations of the influence of viscosity and compressibility of aerated hydraulic oil on volumetric and mechanical losses in a pump of HYDROMATIK A7V.58.1.R.P.F.00 type [8, 9].