**1. Introduction**

Most machines and mechanisms as part of their design have rotating elements that transfer the load to the stator through bearings. Structurally, they can be of various types, and the possibility of functioning of the entire device depends entirely on their performance.

Even higher requirements are placed on bearings that are used in the rotor bearings of aircraft gas turbine engines. With a small mass, they must transmit large variable loads and work with high speeds of movement of the contacting parts of their design.

When designing rotor systems of gas turbine engines (GTEs), many years of experience in the development of such structures are taken into account, and computational simulations and their verification are carried out based on the results of various integrated tests. Such methods of calculation and full-scale experiment take

#### *Advances in Turbomachinery*

into account and repeatedly check the influence of a large number of external and internal factors that can drastically reduce the duration of uptime of engines.

At the same time, despite the progress made in the field of computer design, simulation, and testing, it will never be possible to take into account the entire set of product states due to the manifestation of all possible combinations of values of the influence of various factors that may arise during long-term operation of engines.

Given the importance of ensuring long-term trouble-free operation of the bearings of the rotor systems of GTE, the most promising trend can be considered as the provision of such a design with a developed monitoring and diagnostic system. It should provide a permanent opportunity to determine the technical condition of the bearings in all operating modes of the engine and issue warnings to the crew in cases of rapidly developing damage to their parts.

In view of the importance and complexity of this issue, we have set a goal to provide the possibility of diagnosing the inter-rotor bearing of the GTE turbine support by developing nontraditional diagnostic methods.

Modern methods and algorithms are required not only to diagnose existing defects but also to detect changes in the state of the system before an emergency occurs. In this direction, it is worth noting the works of domestic scientists: [1].

For technical diagnostics of nonstationary systems, a wavelet transform is used, which makes it possible to adapt to the local properties of the signal, which increases the efficiency of diagnostics. This is evidenced by the works of scientists such as [2–4]. Wavelet the transform gives a time-frequency representation of the signal, thereby avoiding many of the problems that arise when using the Fourier transform. The impulses of the system under study can have an arbitrary shape; therefore, to describe them, it is necessary to use orthogonal functions. The most popular orthogonal wavelets are the Haar and Daubechies wavelets [5]. They have a number of limitations and disadvantages. Haar wavelets poorly describe smooth functions, and Daubechies functions have an asymmetric form, which narrows the area of their practical use. Thus, with the help of classical wavelets, it is not possible to take into account all the features of the pulse shape, which affects the quality of diagnostics. In this regard, when processing real signals, it is necessary to construct a "mother" function based on a discrete record of the signal, and this is absent in the classical interpretation of the wavelet transform.

This goal can be achieved by solving the following tasks:

