Investigation of the impact of unsteady air flows on the mechanical and operational properties of aircraft structural elements

Abstract

The use of pulsating subsonic gas flow treatment (gas pulse treatment) in the process of maintenance and repair for a duration not exceeding a certain value contributes to the restoration and improvement of mechanical and operational properties of aeronautical equipment structural elements. This article presents the results of a study to determine the optimal duration of gaspulse processing of aircraft parts, as which, the duration of processing was adopted, providing the maximum increase in the properties of material viscosity, which prevents crack development without reducing the strength properties. As a result of the study, the influence of various factors, such as the subsonic airflow velocity and the frequency of oscillations, the material and geometric parameters of the processed product, on both the optimal and leading to a decrease in mechanical properties duration of processing by pulsating airflow of aircraft structural elements during maintenance and repair, was evaluated. It has been established that mechanical waves generated by gas flow pulsations can have a significant impact on the structural strength of aircraft structural elements, which makes it possible to increase their reliability as well as the accuracy of forecasting the technical condition. The harmonic nature of the attenuation of the ratio of residual stresses to their initial values has been experimentally established, depending on the duration of gas pulse treatment, which allows us to control their magnitude and sign. An empirical formula has been obtained to determine the optimal processing time for products of various materials. As an indicator of the duration of gas pulse treatment, an increase in the viscosity of the material was adopted without reducing the strength properties. Graphical dependences of the relative time of gas pulse processing, which provides an increase in the mechanical properties of the relative frequency of the gas flow oscillations, have been constructed.