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Vibration mode shape extraction of bladed disk
Mekhalfia, Mohammed Lamine; Procházka, Pavel; Tchawou Tchuisseu, Eder Batista; Maturkanič, Dušan; Hodboď, Robert
2022 - English
This research paper deals with the experimental protocol followed to visualize the vibration mode shape of an aero-engine bladed disk. This study is based on a comparison between the numerical results obtained through Finite element methods (FEM) using ANSYS software and experimentally using the laser Doppler vibrometer. Therefore the bladed disk was transformed into a 3D virtual environment and structural analysis was performed. The results demonstrate a match between the numerical and the experimental one, this match offers the possibility for using the model for future studies.
Keywords:
blade disk; mode shapes; laser doppler vibrometer
Available at various institutes of the ASCR
Vibration mode shape extraction of bladed disk
This research paper deals with the experimental protocol followed to visualize the vibration mode shape of an aero-engine bladed disk. This study is based on a comparison between the numerical results ...
Approaches to dynamical analysis of rotors with parameters of uncertain magnitudes
Zapoměl, Jaroslav; Kozánek, Jan; Košina, Jan; Cibulka, Jan
2022 - English
In many cases, the rotor configuration or loading characteristics are described by parameters of uncertain magnitude. Several procedures were developed to analyse such systems. This paper deals with the approach based on application of the fuzzy numbers. The investigated mechanical system is a rotor supported by hydrodynamic bearings. The parameters of its loading have uncertain values.
Keywords:
rotors; uncertain parameters; fuzzy numbers approach
Available at various institutes of the ASCR
Approaches to dynamical analysis of rotors with parameters of uncertain magnitudes
In many cases, the rotor configuration or loading characteristics are described by parameters of uncertain magnitude. Several procedures were developed to analyse such systems. This paper deals with ...
Turbine blade linkages in reduced modal synthesis model
Pešek, Luděk; Šnábl, Pavel
2022 - English
The paper is the first stage of our modelling turbine blade linkages in reduced modal synthesis model. The modal synthesis method is used for the dynamic behaviour studies of turbine bladed wheels with frictional inter-blade linkages and in case of the microslips the stiffening effect of the linkages play an important role in wheel dynamics. The paper presents the first results of modal analysis of the wheel when springs were used to substitute the linkages in the modal synthesis model.
Keywords:
bladed wheel; reduced model; tie-boss; shroud; stiffening
Available at various institutes of the ASCR
Turbine blade linkages in reduced modal synthesis model
The paper is the first stage of our modelling turbine blade linkages in reduced modal synthesis model. The modal synthesis method is used for the dynamic behaviour studies of turbine bladed wheels ...
Aeroacoustic Noise Source Investigation in the Case of the Blade Cascade
Procházka, Pavel P.; Antoš, Pavel; Šnábl, Pavel
2022 - English
The blade cascade consisted of five NACA 0010 profiles is examined in the framework of project dealing with nonlinear dynamic phenomenon related to stall flutter of flexible profiles with pitch degree of freedom in subsonic flow. Various angles of attack (AoA) of the cascade generates different (broadband) aeroacoustic noise. The goal of this article is to describe the existence of possible noise sources using two experimental methods – Particle Image velocimetry (PIV) and hot-wire (HW) anemometry.
Keywords:
blade cascade; time-resolved PIV; HW anemometry; FFT
Available at various institutes of the ASCR
Aeroacoustic Noise Source Investigation in the Case of the Blade Cascade
The blade cascade consisted of five NACA 0010 profiles is examined in the framework of project dealing with nonlinear dynamic phenomenon related to stall flutter of flexible profiles with pitch ...
Temporal, Spatial, and Spatio-temporal correlation of the velocity fluctuations
Jurčáková, Klára
2022 - English
Taylor's hypothesis about frozen turbulence [1] says that if the turbulence intensity is small compared to the mean velocity then the advection of a turbulent flow field past a fixed point can be taken entirely due to the mean flow. This means that in the “frozen turbulent field” spatial and temporal dimensions can be interchanged. Although the main assumption of Taylor's hypothesis is not met in the atmospheric boundary layer (the intensity of turbulence is usually between 10 and 20%) the hypothesis is commonly used to calculate integral length scales of turbulent fields from point measurements. Particle image velocimetry with high temporal resolution (TR-PIV) allows us to analyze both temporal and spatial cross-correlations in the turbulent flow fields and to evaluate obtained results.
Keywords:
frozen turbulence; wind tunnel; integral length scales; Particle Image Velocimetry
Available at various institutes of the ASCR
Temporal, Spatial, and Spatio-temporal correlation of the velocity fluctuations
Taylor's hypothesis about frozen turbulence [1] says that if the turbulence intensity is small compared to the mean velocity then the advection of a turbulent flow field past a fixed point can be ...
Problematics of aerodynamic damping calculation from measured data of 5-blade cascade
Šnábl, Pavel; Pešek, Luděk; Prasad, Chandra Shekhar; Chindada, Sony
2022 - English
Aerodynamic damping as a function of inter-blade phase angle (IBPA), so called S-curve, is crucial for assessment of aeroelastic stability of blade cascades, e.g. turbines, compressors, etc.\nFor constructing the S-curve, the motion-induced controlled flutter is introduced to the bladesof the cascade. As decribed in [1], two testing methods exist: aerodynamic influence coefficient\n(AIC) approach and travelling wave mode (TWM) approach. In TWM approach, all blades in a row oscillate with the same frequency and amplitude with various IBPAs. The response is\nmeasured only on the reference blade. With this approach, several measurements with different IPBAs are needed to construct the S-curve. On the other hand, AIC uses single oscillating\nblade and principle of linear superimposition of aerodynamic influence responses measured on all blades in a cascade. The result of one single measurement can be used for estimation of\naerodynamic damping for any IBPA. In the past year a new 5-blade cascade with rotating symmetrical NACA 0010 profiles was designed and built. The blades of the cascade were placed further apart and thus we are now able to reach stall flutter. Also, the suspension of the blades and sensors were significantly improved. Now, our goal is to evaluate S-curves using AIC approach for different flow conditions and oscillation frequencies.
Keywords:
aerodynamic damping; S-curve; blade cascade
Available at various institutes of the ASCR
Problematics of aerodynamic damping calculation from measured data of 5-blade cascade
Aerodynamic damping as a function of inter-blade phase angle (IBPA), so called S-curve, is crucial for assessment of aeroelastic stability of blade cascades, e.g. turbines, compressors, etc.\nFor ...
Use of active power filter to reduce flicker caused by electric arc furnace operation
Čerňan, Martin; Bejvl, Martin; Šimek, Petr; Valouch, Viktor
2022 - English
Effectiveness of using a parallel active power filter to compensate for the flicker of an electric arc furnace,\nand mitigate the reactive power consumption and terminal\nvoltage variation in the grid is presented and evaluated in the contribution. The model of a power system with the electric arc furnace and parallel active power filter in the frequency domain has been developed. The selected results of simulation in the frequency domain using the data collected from the 60 t EAF are presented and evaluated.
Keywords:
electric arc furnace; flicker mitigation; active power filter; power system model; simulation in frequency domain
Available at various institutes of the ASCR
Use of active power filter to reduce flicker caused by electric arc furnace operation
Effectiveness of using a parallel active power filter to compensate for the flicker of an electric arc furnace,\nand mitigate the reactive power consumption and terminal\nvoltage variation in the grid ...
Identification of the blade tip possition and measurement techniques using the BTT method
Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Mekhalfia, Mohammed Lamine
2022 - English
This paper describes the existing practice in identifying and defining the position of the blade tips and the relevant technique for measuring their vibration during rotation. In connection with the effort to precisely define the position of the vibrating blade, the paper also analysed the possibilities of unambiguous determination of its position. This work creates a parallel branch to signal processing in the complex system of precision measurement and analysis of blade vibration, which was mentioned in previous papers.
Keywords:
turbine blade; vibration; precision method; modification; harmonic function
Available at various institutes of the ASCR
Identification of the blade tip possition and measurement techniques using the BTT method
This paper describes the existing practice in identifying and defining the position of the blade tips and the relevant technique for measuring their vibration during rotation. In connection with the ...
Measurement and analysis of vibration and acoustic emissions of a railway wheel under defined dynamic excitations
Pešek, Luděk; Prasad, Chandra Shekhar; Šnábl, Pavel
2022 - English
The paper deals with experimental vibro-acoustics of railway wheel. The methodology for evaluation of effect of vibrational plate dampers was elaborated. The four variants of the wheel was measured and analyse to achieve the optimal solution of the dampers.
Keywords:
vibro-acoustics; railway wheel; dampers; noise
Available at various institutes of the ASCR
Measurement and analysis of vibration and acoustic emissions of a railway wheel under defined dynamic excitations
The paper deals with experimental vibro-acoustics of railway wheel. The methodology for evaluation of effect of vibrational plate dampers was elaborated. The four variants of the wheel was measured ...
Study of the oscillation of a pendulum in a magnetic field
Zapoměl, Jaroslav; Kozánek, Jan; Košina, Jan; Cibulka, Jan
2022 - English
Realization of some technological processes requires application of rotating machines with a vertical rotor mounted in rolling element bearings. One of the requirements put on their operation is minimization of energy losses in the support elements. The proposed design variant consists in supporting the vertical rotor by one rolling element bearing placed at its upper part and by one axial magnetic bearing mounted in its lower end. The magnetic bearing is composed of an electric coil coupled with the stationary part and of a permanent magnet attached to the rotating part. The magnetic force attracts the permanent magnet, which reduces radial displacement of the lower end of the rotor. The magnetic field between the magnets represents a force coupling between the rotor and the stationary part, which shows some stiffness and affects the system natural frequencies. The controlled change of the stiffness makes it possible to reduce the rotor lateral oscillations in the resonance area. The investigated pendulum is coupled with the frame by a revolute joint at its upper end. The permanent magnet is attached to its lower end. The electric coil is coupled with the stationary part and placed under the pendulum. The system is excited by a moment of harmonic time history, which sets the pendulum into a seesaw motion.\n\n
Keywords:
vertical rotor; pendulum; axial magnetic bearings; lateral oscillations; resonance
Available at various institutes of the ASCR
Study of the oscillation of a pendulum in a magnetic field
Realization of some technological processes requires application of rotating machines with a vertical rotor mounted in rolling element bearings. One of the requirements put on their operation is ...
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