Авіаційно-космічна техніка та технологія (Aug 2020)
MATHEMATICAL MODEL OF FUEL PUMP-REGULATOR OF HELICOPTER TURBO-SHAFT ENGINE
Abstract
This article discusses the relevance of creating a mathematical model of a hydromechanical fuel regulator as the main component of the parametric diagnostics method. To understand the processes occurring during the operation of the fuel regulator, this article provides a brief description of its operation. Based on the problems solved by the diagnostic methods and the features of the fuel regulator, the basic requirements for its mathematical model are formulated and the structure of this model is determined. Several assumptions are made (one-dimensional flow of the working fluid and its zero thermal conductivity), which make it possible to significantly simplify the structure of the model and the number of simulated parameters. The mathematical model consists of idealized elements with lumped parameters (such as pressure and flow rate of the working fluid), takes into account the compressibility of the working fluid, as well as the design features of the regulator (mechanical stops, complex profiled dosing windows of spools, relay-type switches). As an example, this article contains equations for the elements with lumped parameters, interconnected by hydraulic channels in one node. The compiled mathematical model is a system of differential-algebraic equations of the first index. To solve such a system, a special implicit solver is used. The calculation of the parameters of the mathematical model for static and transient operating modes of the fuel regulator has been made. The results of calculating the model parameters in various modes are compared with the requirements for these parameters set in the technical specifications for the simulated fuel regulator. The correspondence of the calculated parameters to the values specified in the technical documentation was ensured by the selection of input parameters (tightening of springs of elastic elements, area of throttling elements, etc.). From the results obtained, it was concluded that the model makes it possible to diagnose the technical state of the fuel regulator at the stages of adjustment during production and repair, as well as at the stage of its operation.
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