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2 Polish Maritime Research

2 2013

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

Paszota Z.

Polish Maritime Research

2013

nr 3

3--13

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 ΔMPm|ΔpPi = pn, qPgv of torque of mechanical losses is proportional to the indicated torque MPi|ΔpPi = pn, qPgv determined with a fixed value ΔpPi = cte of increase of pressure in the pump working chambers. The fixed value ΔpPi assumed in searching the liquid aeration coefficient ε equals to the nominal pump operation pressure pn (ΔpPi = cte = pn ). The increase ΔMPm|ΔpPi = pn, qPgv of torque of mechanical losses with a fixed value of ΔpPi (ΔpPi = cte) is proportional to the pump geometrical working capacity qPgv , therefore: only with taking into account the aeration coefficient ε of liquid displaced by the pump the relation ΔMPm|ΔpPi = pn, qPgv ~ qPgv 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].

Influence of viscosity and compressibility of aerated oil on determination of volumetric losses in a variable capacity piston pump

Koralewski J.

Polish Maritime Research

2013

nr 4

3--17

Modulus B of the liquid volume elasticity of non-aerated and aerated oil is defined in the paper as relation to the indicated increase of pressure in the pump working chambers, with the change of oil temperature and degree of aeration. In evaluation of the losses due to oil compressibility in a variable capacity displacement pump, the volume of compressed liquid at each pump setting is taken into account. Volumetric losses have been divided into leakage losses in the pump chambers and losses due to liquid compressibility. The need of accounting for only the leakage losses for pump evaluation is pointed out.