FORMALIZATION OF MODE-DEPENDENT CRITERIA OF THE DIAGNOSTIC MODEL OF THE TV3-117V GAS TURBINE ENGINE FOR POST-FLIGHT ANALYSIS

Abstract

Subject of research. The subject of the research is the formalization methods for mode-dependent criteria of preliminary parametric control of the working process of the TV3-117V gas turbine engine based on post-flight data. Purpose. The purpose of the work is to form a structure of mode-dependent criteria that makes it possible to evaluate deviations of the actual behavior of analog engine parameters from the expected behavior for the corresponding operating mode. Tasks. To achieve this purpose, a set of analog parameters characterizing the thermal, gas-dynamic, and mechanical state of the engine gas path was determined; the mode basis of post-flight parametric control was refined; a general structure of a mode-dependent criterion was developed; criteria for ground idle mode, cruise mode, takeoff mode, and 2.5-minute power mode were formed; and a logic for combining local criteria into a preliminary diagnostic conclusion was proposed. Methods. The research methodology is based on system analysis of engine operating parameters, formalization of logical rules for post-flight control, comparison of actual parameters with reference or expected behavior, and consideration of the operating mode, deviation duration, rate of parameter change, trend behavior, and inter-parameter consistency. Results. A general structure of a mode-dependent criterion is proposed, taking into account the engine operating mode, actual parameter value, reference or allowable value, deviation magnitude, rate of parameter change, deviation duration, and inter-parameter relationships. Groups of criteria for the main operating modes of the TV3-117V engine were formed. For ground idle mode, criteria of temperature exceedance, rapid temperature increase, rotor speed deviation from the allowable range, and inconsistent variation of exhaust gas temperature and torque were considered. For cruise mode, criteria for gradual thermal deviation, reduced fuel efficiency, gas-dynamic inconsistency, and exceeding the expected trend in exhaust gas temperature and fuel flow rate were established. For takeoff mode and 2.5-minute power mode, criteria for monitoring limiting thermal and mechanical loads, duration of operation in the mode, and parameter recovery after increased load were proposed. Conclusions. The proposed approach enables the transition from a descriptive representation of post-flight analysis to a structured set of algorithmically applicable rules for preliminary parametric control. The presented criteria do not constitute a complete diagnostic model of the engine gas path and are not intended to independently determine a specific fault type. Their practical application requires further refinement of allowable deviations, time delays, weighting coefficients, and reference trajectories based on bench tests, operational statistics, or a computational engine model. Scientific novelty of the obtained results. The scientific novelty consists in refining the structure of mode-dependent criteria for preliminary parametric control of the working process of the TV3-117V gas turbine engine, in which parametric deviations are considered with regard to the operating mode, duration of manifestation, rate of parameter change, expected natural trend, mode phase, and inter-parameter consistency.