# FSI Application in the Parametric Analysis of Blade-Disk Connection of Turbojet Engine Compressor
## 1 Introduction  
Issues related to the design of rotor systems, including compressors, are solved in many ways, including frequency analyses [1, 2]. These studies, in addition to numerical analyses, are carried out by way of experiments to eliminate overlapping frequencies of components, for example, disks and blades. The work of these elements in the same frequencies leads to fatigue problems. This issue was addressed in the work of [PERSON] et al. [3]. In the paper, a decision was made to replace the standard crack simulation model with a three-dimensional comparable notch model, which turned out to be more convenient for analyzing the impact of cracking on the strength of the rotor system. [PERSON] et al. [4] presented the results of a vibration analysis of the rotor stage structure with a standard lock connection. The cycle analysis method and ANSYS 2020 R2 software were used for this. The analysis showed that as the rotational speed gradually increased, the stiffness and frequency of the natural vibrations of the structures increased. The increase occurred only until a certain range of rotational speed was reached. In the analysis of rotor stages, an important issue is to estimate the service life of the structure at the time of the appearance of cracks. For this purpose, among other things, the method of damage tolerance analysis is used. [PERSON] et al. [5] analyzed the process of crack propagation in the example of a rotor blade. The possibility of limiting crack propagation in the case of low-cycle fatigue of the construction was also checked. Another significant issue in compressors is the stall. This phenomenon has a very negative effect on the stable operation of the compressor and significantly limits its operating range. It also has a significant impact on the service life of the rotor blades. [PERSON] et al. [6] analyzed the influence of the stall pressure wave on the non-synchronous vibrations of the blades induced by it. The issue is important at an early stage of design to eliminatesmall resonance. Nowadays, there are works solving the problem of strength calculations of rotor assemblies using artificial neural networks. [PERSON] et al. [7] presented the use of artificial neural networks to determine the stress distribution in the disk-drum stage of an aircraft turbine engine compressor. The presented algorithm made it possible to determine stress values that could be used for further mass optimization of the entire structure. The compressor is one of the main components of the turbine engine, and the performance of the powerplant depends on its effective operation (Figure 1). This component is responsible for supplying the combustion chamber with the necessary amount of air while increasing its pressure to the required value and ensuring a uniform flow field. Currently, twin- or triple-rotor axial compressors are used in turbofan engines (three-rotor compressors are characteristic of Rolls Royce engines). There is one low- and one high-pressure compressor, and in the case of three-rotor designs, an additional medium-pressure compressor. In the case of high-bypass ratio turbofan engines, there is a single-stage fan in front of the compressors that supplies air at a specific rate and pressure to the internal and external ducts of the engine [8]. Currently, multi-stage axial compressors dominate in aviation turbine engines, in which the axial compressor rotor consists of several stages [8]. Each step consists of a support element and blades attached to it. Blades are usually made as separate elements, which allows for their easy assembly and disassembly during maintenance or repair. There are three basic structural systems of the compressor rotors' supporting elements: drum, disk, and drum-disk. Each of these systems is still used in modern turbojet engines, both with high and low bypass ratios, in civil and military aviation, respectively. The critical area of the rotor stage structure of a turbojet engine is the place where the blade is attached to the disk rim.