Abstract

The conducted investigations aimed to carry out an analysis of the possibility that the failures identification in the automatic control system of a gas turbine engine could be worked out on the basis of measurements of the exhaust stream temperature behind the gas generator. The exhaust temperature represents a basic control parameter, enabling technical state evaluation of the engine within the operation process, which is observed during engine's start-up, rotor units' acceleration and deceleration as well as during engine's steady load states. A range of the article has been limited to present only results of diagnostic examinations worked out on two and three-shaft engine with free power turbine in the range automatic control subsystem limiting the maximum exhaust temperature during the engine's start-up process. This type of investigation has been carried out on the stopped engine, by means of testers especially designed to simulate an action of the exhaust temperature protection's modules. The investigation aimed to evaluate a correctness of the threshold (maximum) setting values of the exhaust stream temperature behind the gas generator as well as such its time increases in which the executive elements of the automatic control system start-up dosing channels of the engine's fuel fed system: overflow channel, drainage channel as well as the channel of engine's immediate lay-off. The evaluated in this way borders of the tolerance's operation field represent admissible values of the alteration of this parameter during steady and unsteady engine's running. However, the systematically conducted simulating diagnostic investigations on engines being in current operation give a possibility of the early detection of primary damages of control system's elements which might lead to thermal overload of constructional elements in a ''hot" engine's section.

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