National Repository of Grey Literature 69 records found  1 - 10nextend  jump to record: Search took 0.05 seconds. 
Statistical Approach for BTT probes distribution
Mekhalfia, Mohammed Lamine ; Procházka, Pavel ; Šmíd, R. ; Tchawou Tchuisseu, Eder Batista
Blade tip timing (BTT) system is a non-invasive method used for measuring the blade tip timing of rotating machinery. The BTT system typically consists of sensor probes, signal conditioning system, and data acquisition unit. The sensor probes are placed in proximity to the rotating blade tips, Sensors measure the time at which each blade passes by the probe. By measuring the blade tip timing, the BTT system can detect changes in the blade tip vibration, which is an important for the health monitoring and performance optimization of rotating machinery [1]. To ensure accurate measurement of blade tip timing, the probe arrangement is crucial. The placement of the probe relative to the blade tips can affect the measurement accuracy, and thus, several arrangement algorithms have been developed to optimize the placement of the probes. Instead of considering the condition number, a statistical algorithms is followed to optimize the placement of probes for accurate measurement of blade tip timing in turbo-machinery. The statistical approach will be employed to determine the optimal locations for probes, with the aim of reducing errors in the measurement of blade tip timing. \n
A short study on self-balancing of vertical rotors mounted in passive contactless bearings
Zapoměl, Jaroslav ; Kozánek, Jan
Energy losses and wear of the support elements of high-speed rotors can be reduced by mounting the rotors in stable passive contactless bearings, the operation of which is based on magnetic levitation. The goal of the conducted research was to investigate applicability of self­balancing device added to vertical rotors supported by bearings showing low stiffness and damping, which is a specific property of passive magnetic bearings. This paper deals with applicability and efficiency of self-balancing devices added to vertical rotors supported by bearings having very low stiffness and damping, which corresponds to the properties of magnetic frictionless bearings.
Applications of blade vibration measurements in the laboratory of rotational laser vibrometry
Maturkanič, Dušan ; Procházka, Pavel ; Hodboď, Robert ; Mekhalfia, Mohammed Lamine ; Voronova, Evgeniya
The Laboratory of Rotational Laser Vibrometry was established at the Institute of Thermomechanics AS CR, v.v.i. in 2015 and the first experiments were started the following year. The measurements are intended for the research of vibration of rotating blades. The paper includes a summary of measurement results using a special turbine model and their consequences in theoretical research, as well as measurements with a real compressor of aircraft engine and comparison with computational analysis. The paper also describes the complex system for measurement and analysis.
Self-balancing of vertical disc rotors supported by contactless bearings
Zapoměl, Jaroslav ; Kozánek, Jan ; Košina, Jan
Article discusses the self-balancing of the vertical disc rotors supported by contactless bearings on principle of diamagnetic levitation. There are three possibilities of contactless supports: permanent magnet levitation with the help of bismuth, graphite and pyrolitic graphite.
Dynamics of Machines and Mechanical Systems with Interactions, DYMAMESI 2023
Zolotarev, Igor ; Pešek, Luděk ; Kozień, M. S.
The aim of the DYMAMESI is to facilitate the exchange of up to date information and knowledge among specialists in structural and multibody dynamics, in coupled interacting systems as aero-elasticity, hydro-elasticity, biomechanics, systems with feedbacks and mechatronics. The colloquium DYMAMESI 2021 is cofunded by the Strategy AV21 initiative of the Czech Academy of Sciences of the Czech Republic, and in 2021 will be hosted by Cracow University of Technology, Institute of Applied Mechanics, Section of Dynamics of Systems.
Organic fluorine content and change during thermal treatmen
Hušek, Matěj
We have previously described how pyrolysis affected the content of selected PFAS representatives.4,5 However, we could not determine with certainty whether they were merely cleaved or mineralised. Therefore, we focused on the change in organic fluorine content (part of PFAS) and analysed its thermal behaviour in inert (sea sand) and heterogeneous (sewage sludge) material.
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Different Boundary Conditions For LES Solver PALM 6.0 Used for ABL in Tunnel Experiment
Řezníček, Hynek ; Geletič, Jan ; Bureš, Martin ; Krč, Pavel ; Resler, Jaroslav ; Vrbová, Kateřina ; Trush, Arsenii ; Michálek, Petr ; Beneš, L. ; Sühring, M.
We tried to reproduce results measured in the wind tunnel experiment with a CFD simulation provided by numerical model PALM. A realistic buildings layout from the Prague-Dejvice quarter has been chosen as a testing domain because solid validation campaign for PALM simulation of Atmospheric Boundary Layer (ABL) over this quarter was documented in the past. The question of input data needed for such simulation and capability of the model to capture correctly the inlet profile and its turbulence structure provided by the wind-tunnel is discussed in the study The PALM dynamical core contains a solver for the Navier-Stokes equations. By default, the model uses the Large Eddy Simulation (LES) approach in which the bulk of the turbulent motions is explicitly resolved. It is well validated tool for simulations of the complex air-flow within the real urban canopy and also within its reduced scale provided by wind tunnel experiments. However the computed flow field between the testing buildings did not correspond well to the measured wind velocity in some points. Different setting of the inlet boundary condition was tested but none of them gave completely developed turbulent flow generated by vortex generators and castellated barrier wall place at the entrance of the aerodynamic section of the wind tunnel.
Effect of particle size of high-temperature biochar on its properties
Sedmihradská, Anežka ; Skoblia, S. ; Beňo, Z. ; Moško, Jaroslav ; Fajgar, Radek ; Soukup, Karel ; Pohořelý, Michael
High-temperature biochar is an increasingly used soil amendment, especially in areas where the physical properties of the soil need to be improved. This ecologically promising material has so far been studied mainly in relation to production temperature or the input material. The effects of particle size on the properties of biochar have so far been studied insufficiently. This work seeks to expand the knowledge in this particular area. \n
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Comparison of properties of biochars based on different types of sewage sludge.
Moško, Jaroslav ; Beňo, Z. ; Hušek, Matěj ; Komárek, M. ; Vítková, M. ; Pohořelý, Michael
The application of sewage sludge to agricultural land is an increasingly debated topic, particularly because of the precautionary principle regarding the content of inorganic, organic and microbial pollutants. One of the practices treatment/treatment of sludge prior to land application is pyrolysis, whereby \nbiochars are produced from the sewage sludge, which, provided that proper process management, stable and free from organic and microbial \ncontamination. The aim of this paper was to verify the properties of biochars from sewage sludge that were subjected to different types of stabilization. The sludges were pyrolyzed at temperatures ranging from 600 to 650 °C and a certain correlation was found between degree of sludge stabilization and biochar properties (textural properties, elemental composition, energy value). \n\n
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Utilization of solid sorbents for high temperature removal of halogenated compounds from pyrolysis of waste plastic
Šrámek, Vít
This work focuses on high temperature removal of halogenated compounds in model mixture with hydrocarbons and other compounds. The study was performed in laboratory apparatus under controlled temperature and gaseous mixture composition.\n
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