Dvirnyk Y. Determination of limit state of turboshaft engines by the criterions of compressor vibration and gas-dynamic stability.

The research object is the process of GTE compressor gas-dynamic and vibrational stability changing that is subject to dust erosion due to the operation in a dusty atmosphere. The research subject is the effect of the compressor blades geometric characteristics changing on the natural frequencies, fields of pressure distribution, flow rates and gas-dynamic stability margins of the compressor due to the deterioration. Research methods: numerical finite element method for the compressor rotor blades modal analysis and gas-dynamic evaluation, the method of metrology for estimating changes in the geometry of the blade profile, the method of statistical analysis to process the experimental data, build models and evaluate their adequacy. The objective of the research is to improve the accuracy of evaluation of the helicopter engines limit state that operates under dusty atmospheres. The results attained: Based on the analysis of the geometry of compressor blades after operating in a dusty atmosphere, the stages for which maximum wear and close correlation between the wear of the blades of different stages are determined. Based on the modal analysis of the compressor blades, the maximum allowable wear of the rotor blades of all stages is determined according to the criterion of vibration stability. It has been established that, by the criterion of the gas-dynamic stability of the compressor, the limiting factor is the wear of the chord of the sixth stage rotor blade in the peripheral part by the amount of 6.2 mm. Recommendations for the evaluation of the limit state of the compressor are developed. The expected annual economic effect due to the implementation of the developed recommendations is assessed as a result of the appointment of scientifically based standards for the compressor blades maximum wear. Introduced at "Motor Sich" JSC. Area of application - aircraft engine building.