Test method for determination of individual components of volumetric losses in power supply units
Aerospace propulsion engineering
1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
AbstractThe paper adduces a method of determination of individual components of power losses in power supply units of hydraulic systems.
Determination of individual components of volumetric and mechanical losses in hydraulic pumps of power supply units allows to define the following: the temperature conditions of the hydraulic machine; loads acting on the structural elements, many of which (piston bearings, a flat fixed valve, a face seal) are essentially hydrostatic bearings. Besides such determination allows to select the right structure of the pressure and consumption unloading system, which leads to reduction of some individual components of the losses.
The paper presents a mathematical model of the hydraulic machine efficiency depending on dimensionless groups, which describe its mode of operation as well as structural and technological quality of its implementation. These groups include coefficients of working fluid leakages, dry and fluid friction coefficients. Coefficients of similarity of operation modes of the hydraulic machine depend on the statistical coefficients of individual types of losses, which can be defined on the basis of experimental research of various types of pumps.
The defined above dimensionless groups and their connection to the quality parameters (leakage and friction coefficients) indicate the areas of optimum operation of power supply units and hydraulic machines.
Experimental research, which is connected to volumetric losses via the pump control mechanism, was conducted. Pressure fluctuations in the pressure pump line, overpressure upon activation of hydraulic power consumers and service life of the pump depend on the performance capability of this pump control mechanism.
The operation of the pressure and consumption unloading system leads to the change of the control system configuration. A transition from the differential throttle control system to the direct acting regulator and vice versa takes place. This transition is accompanied by the change of loadings on the feeder control unit and change of the components of the volumetric losses, the value of which should be determined for the specified operation modes.
The results of the research can be used for the design of power supply units with pressure and consumption unloading. The application of the proposed method results in significant reduction of heat emission both in power supply unit and in the whole system. This in turn reduces the weight of the heat-exchanger devices respectively.
Keywords:the hydraulic machine, the axial-piston pump, operation mode coefficients, volumetric and mechanical losses, performance efficiency, pressure and consumption unloading, friction coefficient, volumetric losses coefficient, parameters of hydraulic machine control
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