|
|
Computational and experimental assessment of natural frequencies in a bladed disk system
Mekhalfia, Mohammed Lamine ; Procházka, Pavel ; Maturkanič, Dušan ; Voronova, Evgeniya ; Hodboď, Robert
This paper examines the modal characteristics of a bladed disk in rotating machinery systems using a combination of analytical and experimental modal analysis methods. The analysis involves measuring natural frequencies and mode shapes under different operational conditions. A comparative analysis is conducted to assess modal properties obtained from both analytical and experimental approaches, while also considering the influence of rotation speed. Additionally, Finite Element Method (FEM) outputs are used to accurately position the strain gauge. Integrating these techniques provides a comprehensive understanding of the bladed disk's behaviour under varying rotational speeds, enhancing result accuracy and facilitating thorough investigation within rotating machinery systems.
|
|
| |
|
| |
|
|
Analysis of the rotor packet prestress on the rotor critical speed
Lekeš, Filip ; Huzlík, Rostislav (referee) ; Lošák, Petr (advisor)
The presented diploma thesis deals with the modeling of the rotor packet in dynamic calculations and analysis of the influence of the packing pressing force on the critical speed of the electric motor. The thesis can be divided into three main parts. The first part discusses the current level of rotor packet modeling in dynamic calculations and also deals with analytical theories for subsequent experimental tests. The second part describes the implementation of two experiments to determine the equivalent modulus of elasticity. The first experiment is a four-point bending test and the second is an experimental modal analysis. The third part is used for comparing the results obtained from experimental tests and describes the calculation of the critical speed of the rotor package pressed on the shaft by the finite element method.
|
|
|
Pressure and velocity pulsations of liquid in thin cylindrical domain
Oborná, Eliška ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
The subject of this diploma thesis is a dynamic analysis of phenomena occurring in the thin cylindrical region, ie in a gab, which flows liquid by the given parameters. Through the simplifications introduced, it comes to the problem of structural and forced vibration for both the horizontal pulsation in a tube and the area of a compensating piston. The described method uses the separation of variables for pressure function. The speed function is derived from the already known pressure field distribution using the Navier-Stokes equation.
|
|
|
Modal analysis of the swirl turbine runner
Valo, Lukáš ; Fic, Miloslav (referee) ; Čupr, Pavel (advisor)
The bachelor’s thesis deals with modal analysis of the swirl turbine runner. The main aim was to determine natural frequencies and mode shapes of the turbine runner. Both detailed and simplified models of geometry of the turbine runner were analysed for two types of boundary conditions. The ANSYS program was used to carry out numerical simulations. Experimental measurement was realised to verify and to compare results of calculations.
|
|
|
Creation of database of stator core stiffness of rotational electrical machines
Podzemný, Zdeněk ; Donát, Martin (referee) ; Dušek, Daniel (advisor)
In this thesis is wrote up a complete procedure of stator core stiffness determination using finite element method (FEM), subsequently, the stator core stiffness database was created according to this procedure. In the next chapter is carried out a sensitivity analysis of one chosen stator core, which led to identifying parameters that affected its stiffness the most. Finally, a modal analysis of one synchronous machine was performed using FEM, in order to determine the effect of stator core stiffness on modal characteristics of the machine. Several modal shapes and corresponding natural frequencies were computed in this analysis, then only a few shapes with the highest core effect were chosen and compared.
|
|
|
Explanation of the sloshing motion in a tank, for a moving tank, for a fixed tank
Mrázek, Michal ; Habán, Vladimír (referee) ; Fialová, Simona (advisor)
This bachelor's thesis deals with mathematical model of sloshing in a tank. Laplace's equation is developed. Boundary conditions for a still rectangular container and for a container under sinusoidal translation are established. Expressions for the free surface elevation and natural frequencies in oscillating tank are determined. Baffles are suggested as a method to minimize the free surface elevation. In the final part, analytical model is compared with numerical solution with overall good agreement.
|
|
|
Numerická předpěťová modální analýza kmene
Skokan, Vojtěch
This work is investigating the effect of prestress on the results of the numerical modal analysis of tree stem and the effects of the degree of simplification of the geometry of the numerical model on the values of natural frequencies and modes of natural oscillation. The work aims to create credible numerical models of trunks and to use prestress to induce such a change in the diameter of the trunk that occurs in trees during the diumal cycle, thus simulating the transpiration stress in the trunk. During the work, three different methods of inducing prestress in the trunk are investigated and their impact on the values of the observed frequencies of strain models is assessed. In addition to artificial prestress, the work also assesses the impacts of the co-effect of gravity on the values of natural frequencies. This work is one of the first attempts to investigate the effect of mechanical stress caused by the transpiration flow using numerical simulation and can thus lay the foundation for future research in this field.
|
|
| |
guest ::
