Methodology of accounting power expended on the rotation of the rotor of aircraft engine in nonlinear dynamic models of start of the aviation engine
The mathematical description of the cost of power for rotating the rotor of an aircraft gas turbine engine has been developed, which taking into account the heating of the oil in the oil system during the start-up and operation of the engine, the power costs for rotating the rotor bearings and for driving various types of aggregates. Description of the loss of mechanical power for rotation of bearings is made in accordance with the theory of hydrodynamic similarity, taking into account the nonstationarity of their work, caused by the slippage of the rolling elements during acceleration and braking of rotor rotation. Oil temperature is determined based on the heat balance equation of the oil system, which takes into account various sources of heat (from friction in the bearings, assemblies, gears, return from the heat exchanger, etc.). The developed description is verified in the simulation nonlinear dynamical model of the GTE by comparing the calculated data on the change in the rotation frequency of the rotor of the engine as a function of time with the experimental data when the engine is started by the starter without ignition of the fuel in hot and cold initial state. The results of simulated engine startup calculations for various ambient temperatures and different initial thermal states are presented with the application of the developed description. The dependences of the rotational power of the bearings and the drive of the units on the thermal state of the engine, the ambient air temperature of the current launch parameters, the design and the algorithm of operation of the starting system are obtained. It is proposed measures to reduce the moment of resistance of the engine at start-up.