Aerospace Technic and Technology

An important direction for the development of aircraft engine building and the design of aircraft engines with an adaptive cycle is the search and formation of scientific and technical achievements, as well as the verification and implementation of technical solutions on existing and proven designs. The use of low pressure turbine nozzle guide vanes variable sectors will allow to mitigate production differences between engines during acceptance tests, as well as to adjust the performance in the process of during service life consumption. The subject of the study is the thermogasdynamic processes in the flowpath of the turbofan engine family when changing the flow area of the low pressure turbine nozzle guide vanes sectors at maximum operating mode. The purpose of the work is to determine the quantitative effect of low pressure turbine nozzle guide vanes variable sectors on the main performance of non-afterburning and afterburning versions of specified engine family. To achieve this purpose, the task of developing a thermogasdynamic mathematical model of engine parameters of the turbofan engine family, taking into account the area variation of low pressure turbine nozzle guide vanes and conducting a numerical analysis of the effect of changing the flow area on specific fuel consumption (SFC) and thermodynamic parameters (Tt41), was solved. The work uses methods of thermogasdynamic modeling of aircraft gas turbine engines, which are based on the numerical solution of systems of nonlinear equations of joint operation of components. The obtained results of calculations on the effect of changing the flow area of the low pressure turbine nozzle guide vanes at different degrees of closure (–5 %) or opening (+5 %) demonstrate that such adjustment can provide the necessary and effective redistribution of energy and working fluid between the spools and the bypass and main ducts of the engines. It is established that the nature and direction of this effect differ for non-afterburning and afterburning versions due to differences in the gas-dynamic flow resistance of the exhaust duct and the presence of variable exhaust nozzle. At the maximum operating mode, adjustment of the area of low pressure turbine nozzle guide vanes sectors for the non-afterburning version will allow to reduce the gas temperature upstream of high pressure turbine rotor wheel by 1.1 %, and for the afterburning version – to reduce the specific fuel consumption by 0.2 %. The main conclusions of the study are to prove the system effectiveness of implementation of variable sectors of low pressure turbine nozzle guide vanes as a tool for flexible control of the work process, which allows expanding the range of stable operation without deteriorating thrust indicators. The scientific novelty of the results obtained lies in establishing the patterns of relationship between the degree of area variation of the low pressure turbine nozzle guide vanes and the work process parameters for the class of aircraft engines of the turbofan engine family. The application of the results obtained will allow increasing thermodynamic efficiency, as well as significantly saving time on design and cost of developing next-generation engines.

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