Проблеми наземних випробувань турбовальних газотурбінних двигунів типу ТВ3-117

During ground tests of TV3-117 gas turbine engines on hydraulic brake systems, self-oscillations of the rotor speed of a free turbine and the parameters of a turbocharger in the area of operation of the free turbine speed regulator are often recorded. One of the reasons for the development of self-oscillations in the automatic control system of a free turbine is the discrepancy between the loading characteristics of the hydraulic braking unit and the loading characteristics of the helicopter main rotor. During ground tests, the object of regulation is a free turbine with a connected hydraulic brake rotor. When the engine is operating as part of a helicopter power plant, the control object is a free turbine with a connected main rotor rotor. Changing the parameters of the controlled object without appropriate correction of the controller parameters can lead to unsatisfactory dynamics of the automatic control system. Another reason for the development of self-oscillations is the nonlinearity of the characteristics of the elements of the automatic control system. The article presents a mathematical model of the system for automatic control of the speed of a free turbine, taking into account the nonlinear features of the characteristics of real regulators. Computational studies of the influence of the rupture of the static characteristic and the zone of insensitivity of the regulator on the development of self-oscillations in the automatic control system of the speed of a free turbine during ground tests of a helicopter engine are carried out. Recommendations are given on the choice of parameters of the free turbine speed regulator to prevent the occurrence and development of self-oscillations of the speed of the turbocharger and free turbine.