Number of found documents: 3104
Published from to

Vysokonapěťový pulzní zdroj a řídící jednotka
Gruber, Jan; Janovec, Jiří; Šonský, Jiří; Němec, Tomáš
2022 - Czech
Zpráva obsahuje popis sestavy vysokonapěťového pulzního zdroje (PPSU) a řídící jednotky (SPCU), které jsou využívány v kombinaci s výbojovou komorou a párem elektrod k aerosolové syntéze nanomateriálů. Uvedena jsou schémata zapojení, seznam elektronických i mechanických součástek, jakožto i popis konektorů a zřetězeného propojení více soustav. Zpráva rovněž obsahuje informace o referenčních parametrech výbojů a popis komunikačního protokolu včetně nastavitelných proměnných. The report contains description of Pulsed Power Source Unit (PPSU) and Spark Control Unit (SPCU), which are utilized in combination with Spark Discharge Chamber and pair of electrodes for aerosol synthesis of nanomaterials. The report includes electronic schematics, list of components, description of connectors and way to chain-link and operate more sets of units. The report also includes information about discharge reference parameters and description of communication protocol and its variables. Keywords: electrotechnics; high-voltage; power transformation; pulse generators Available at various institutes of the ASCR
Vysokonapěťový pulzní zdroj a řídící jednotka

Zpráva obsahuje popis sestavy vysokonapěťového pulzního zdroje (PPSU) a řídící jednotky (SPCU), které jsou využívány v kombinaci s výbojovou komorou a párem elektrod k aerosolové syntéze ...

Gruber, Jan; Janovec, Jiří; Šonský, Jiří; Němec, Tomáš
Ústav termomechaniky, 2022

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 ...

Mekhalfia, Mohammed Lamine; Procházka, Pavel; Tchawou Tchuisseu, Eder Batista; Maturkanič, Dušan; Hodboď, Robert
Ústav termomechaniky, 2022

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 ...

Zapoměl, Jaroslav; Kozánek, Jan; Košina, Jan; Cibulka, Jan
Ústav termomechaniky, 2022

Analytické postupy řešení kmitání lopatek pro použití u metody Blade Tip Timing - teoretický popis metody
Maturkanič, Dušan; Procházka, Pavel; Mekhalfia, Mohammed Lamine
2022 - Czech
Práce je zaměřena na analytický přístup k řešení problematiky kmitání lopatek turbíny a kompresoru metodou Blade Tip Timing. Ve zprávě je navržena nová metoda, pro niž byly stanoveny podmínky řešení. Ověření metody bylo provedeno prostřednictvím simulace, kdy byla vyhodnocena spolehlivost, u které byla zadávána správná vstupní data a výpočet probíhal po dostatečně dlouhou dobu, zatímco na základě záměrně zkreslených vstupních dat byla ověřována její přesnost. Součástí zprávy je také vazba výsledků výpočtu frekvence kolísajících otáček, získaných deterministickou metodou, která byla popsána v předchozích pracích, a s nimiž lze dosáhnout přesnějšího výpočtu frekvence a amplitudy kmitání lopatek v reálných podmínkách.\n\n The report focuses on an analytical approach to solving the problem of turbine and compressor blade vibration using the Blade Tip Timing method. The report contains a description of the new method with defined solution requirements. Verification of the method was performed by simulation, where the correct input data was used in the analysis of the reliability of the method when the calculation was repeated at a sufficiently large number of revolutions, while in the accuracy analysis, intentionally distorted input data was used. The report also includes connection to the results of frequency and amplitude calculation for fluctuating speeds obtained by the deterministic method, which was described in previous works aimed at achieving a precise calculation of the frequency and amplitude of blade vibration in real conditions. Keywords: vibration; blade; analytical method; frequency; amplitude; turbine; compressor; sensor Available at various institutes of the ASCR
Analytické postupy řešení kmitání lopatek pro použití u metody Blade Tip Timing - teoretický popis metody

Práce je zaměřena na analytický přístup k řešení problematiky kmitání lopatek turbíny a kompresoru metodou Blade Tip Timing. Ve zprávě je navržena nová metoda, pro niž byly stanoveny podmínky řešení. ...

Maturkanič, Dušan; Procházka, Pavel; Mekhalfia, Mohammed Lamine
Ústav termomechaniky, 2022

Effect of oscillating blade on tonal noise of blade cascade with five NACA 0010 profiles
Šnábl, Pavel; Pešek, Luděk; Radolf, Vojtěch; Antoš, Pavel; Procházka, Pavel; Prasad, Chandra Shekhar
2022 - English
The airfoil tonal noise is a well known phenomenon which appears on single airfoils in moderate Reynolds numbers at low angles of attack. It can appear on small aircrafts, fans, wind turbines etc. In thispaper, it was observed on a blade cascade consisting of five NACA 0010 profiles placed in a closed rectangularchannel with hard walls when for given conditions, i.e. flow velocity and angle of attack, the cascade tunes to one single frequency. During the middle blade oscillation, the single tone splits up to several tones with lower intensity modulated by the excitation frequency. Thus, the oscillation of one blade suppresses the tonal noise generation in the cascade. Keywords: aeroacoustics; blade cascade; trailing edge noise; tonal noise; NACA 0010 Available in digital repository of the ASCR
Effect of oscillating blade on tonal noise of blade cascade with five NACA 0010 profiles

The airfoil tonal noise is a well known phenomenon which appears on single airfoils in moderate Reynolds numbers at low angles of attack. It can appear on small aircrafts, fans, wind turbines etc. In ...

Šnábl, Pavel; Pešek, Luděk; Radolf, Vojtěch; Antoš, Pavel; Procházka, Pavel; Prasad, Chandra Shekhar
Ústav termomechaniky, 2022

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 ...

Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Mekhalfia, Mohammed Lamine
Ústav termomechaniky, 2022

Estimation of damping IN human vocal folds vibration: measurements in vivo and on model
Horáček, Jaromír; Radolf, Vojtěch; Bula, Vítězslav; Košina, Jan; Geneid, A.; Laukkanen, A. M.
2022 - English
This study investigates the biomechanics of the end-part of phonation, i.e. the so-called phonation offset, experimentally. This information of vocal folds damping is important for testing and further development of mathematical modelling of phonation. The measurements of the damping ratio, based on high-speed videolaryngoscopic registrations, were realized in vivo on a male subject and in vitro using an originally developed silicon replica of the human vocal folds. In both cases the results show remarkable decrease of vibration frequency of the vocal folds and increase of damping ratio D in the phonation offset limiting to the values D=0.12 in vivo measurement and D=0.11 in vitro measurement. The results for vocal folds’ damping are in good agreement with previous measurements performed in humans using different methods. Keywords: phonation offset; high-speed videolaryngoscopy Available at various institutes of the ASCR
Estimation of damping IN human vocal folds vibration: measurements in vivo and on model

This study investigates the biomechanics of the end-part of phonation, i.e. the so-called phonation offset, experimentally. This information of vocal folds damping is important for testing and further ...

Horáček, Jaromír; Radolf, Vojtěch; Bula, Vítězslav; Košina, Jan; Geneid, A.; Laukkanen, A. M.
Ústav termomechaniky, 2022

Experimental investigation of the frequency-modal properties of the measuring container for LUNA mission
Zolotarev, Igor; Bula, Vítězslav; Šnábl, Pavel; Snížek, Jan; Souček, Jan
2022 - English
This paper continues investigations of the measuring equipment for space missions. The frequency-modal properties of the measuring container for LUNA mission were obtained by experimental investigation. Keywords: modal analysis; natural frequencies; modes of vibration Available at various institutes of the ASCR
Experimental investigation of the frequency-modal properties of the measuring container for LUNA mission

This paper continues investigations of the measuring equipment for space missions. The frequency-modal properties of the measuring container for LUNA mission were obtained by experimental ...

Zolotarev, Igor; Bula, Vítězslav; Šnábl, Pavel; Snížek, Jan; Souček, Jan
Ústav termomechaniky, 2022

Survey of the use of propane as refrigerant R290 in cooling circuits and heat pumps
Aminian, Ali; Prokopová, Olga; Vinš, Václav
2022 - English
The technical report presents a review on the application of propane as refrigerant R290 in cooling circuits and heat pumps (HVAC). Safety risks of R290 used in HVAC are addressed according to ANSI/ASHRAE and EN standards. Comparison of thermophysical properties of propane with other refrigerants, solubility and miscibility of propane in compressor oils and heat transfer in condenser and evaporator are discussed. The main aim of the study is to provide an overview about the potential use of propane in the cooling circuit and heat pump for the hydrogen bus developed by the SOR Libchavy company. Keywords: cooling circuit; heat pump; hydrogen bus; refrigerant Available at various institutes of the ASCR
Survey of the use of propane as refrigerant R290 in cooling circuits and heat pumps

The technical report presents a review on the application of propane as refrigerant R290 in cooling circuits and heat pumps (HVAC). Safety risks of R290 used in HVAC are addressed according to ...

Aminian, Ali; Prokopová, Olga; Vinš, Václav
Ústav termomechaniky, 2022

Experimental investigation of homogeneous nucleation of water in various gases using an expansion chamber
Lukianova, Tetiana; Lukianov, Mykola; Hrubý, Jan
2022 - English
Nucleation is an integral part of phase transitions and plays an important role in technology. The control of nucleation in devices such as turbines, rocket and jet engines, wind tunnels, and combustion processes is key to achieving efficient, ecologically sound operation. Our paper presents information about a modernized experimental setup used for homogeneous water nucleation research.\nThe main goal of the study is an analysis of the influence of carrier gas on homogeneous nucleation.The experimental setup based on an expansion chamber has been used for research of homogeneous nucleation over several decades and has undergone various technical improvements. In the Institute of Thermomechanics, the setup was been completely disassembled and cleaned. Pressure transducers, laser, and the data acquisition system have been replaced with modern parts. After that, the chamber was assembled, and thoroughly tested and calibrated.Our investigations were carried with argon and nitrogen as carrier gases in a range of nucleation temperatures 220 – 260 K, pressure range 80-150 kPa, at several concentrations of water vapour. The results thus obtained are consistent with literature data.The findings suggest that this experimental approach is useful for homogeneous water nucleation research. Keywords: homogeneous nucleation; pulse chamber; nucleation rate Available at various institutes of the ASCR
Experimental investigation of homogeneous nucleation of water in various gases using an expansion chamber

Nucleation is an integral part of phase transitions and plays an important role in technology. The control of nucleation in devices such as turbines, rocket and jet engines, wind tunnels, and ...

Lukianova, Tetiana; Lukianov, Mykola; Hrubý, Jan
Ústav termomechaniky, 2022

About project

NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web

Send your suggestions and comments to nusl@techlib.cz

Provider

http://www.techlib.cz

Facebook

Other bases