National Repository of Grey Literature 73 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Effect of the environment on the dynamic properties of simple parts
Nováková, Soňa ; Himr, Daniel (referee) ; Habán, Vladimír (advisor)
The dynamic characteristics of the object are influenced by the changes of the envi-ronment. The objective of this report is to examine how the changes of the environment influ-ence the dynamic characteristics of the object. The main aim is to compare the natural fre-quencies of the object when suspended and then actuated when being surrounded by air and submerged in water. The object in question is a cylindrical pipe, which was gradually short-ened during the experiment. These changes in size also affected the natural frequencies and the mode shape, which is discussed as well. The results of the experimental modal analysis are compared to calculations run in ANSYS software.
Design of orifice plates for steam for high pressure difference
Gajdůšek, Tomáš ; Himr, Daniel (referee) ; Habán, Vladimír (advisor)
The work deals with the design of a system of orifices for high pressure difference. The task of this work is to design a device for controlled discharge of steam-gas mixture from a volume compensator with an overpressure of 12,27 MPa to a tank with an overpressure of 0,02 MPa at a constant mass flow of 40 kg/h. The first part of the thesis contains the theory and also the basic principles of calculations. In the next part of the work, the theoretical properties of flow, such as the speed of sound in wet steam, are determined. This knowledge then serves the main goal of the work, namely to design a system of orifices to release steam-gas mixture from the volume compensator.
Pressure pulsation propagation in elastic hoses
Čapoš, Eduard ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
This thesis deals with propagation of pressure and flow pulsations, which are strongly affected by the tube flexibility. There are two mathematic models introduced, which are derived from basic physical relations. First model assumes velocity only in the axis direction. Second one assumes also non-zero radial velocity. Kelvin-Voigt model for viscoelasticity was used. Furthermore, experimental measurement was designed and evaluated. Measured data was used to calculate material properties. In addition, dynamic transfer was determined.
Analysis of measured signals from cavitation experiments
Asszonyi, Ondřej ; Habán, Vladimír (referee) ; Rudolf, Pavel (advisor)
This thesis focuses on problem with detection of cavitation in hydraulic systems and devices. Thesis works with data from cavitation tunnel experiment, where cavitation appeared on blade. It founds out if time records and their frequency spectrum is dependent on operating conditions. Data are examined by various statistic methods. All of that is then used in method called neural network.
Dynamic properties of tuned branch
Čepl, Ondřej ; Kůrečka, Jan (referee) ; Habán, Vladimír (advisor)
The main part of the thesis is experimental determination of transmission in side-branch resonator. In first part are described basics of digital signal processing and sound damping in piping systems. A special attention is payed to Fourier transform. The second part deals with experimental measurement of damping in a side-branch resonator for several lengths of the resonator. The collected data were analyzed using Fourier transform with a fulfilled coherence condition. At the end of this section are shown graphs, which describe tuning frequency dependence of side-branch resonator's length. There are seven different lengths. The thesis contains comparison of theoretical and measured tuning frequencies.
Use of the dynamic damper in hydrodynamics
Vrána, Jiří ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
The master thesis deals with the possibility of using dynamic damper in hydrodynamics. Specifically, the assessment of the impact of dynamic damper on the dynamic stability of the fluid system when the system exhibited unstable behaviour prior to damper installation due to self-excited vibration. In the thesis is presented the algorithm for the calculation of pressure and flow pulsations based on the transfer matrix method, the transition matrices for different damper designs variants are derived. Using the algorithm, the effect of a damper placed in a stable and unstable fluid system is solved. The output of this work is software for solution of pressure and flow pulsations in the system with serially arranged hydrodynamic elements created in the MATLAB program.
Verification of geometry influence on dynamic properties of immersed body
Černý, Tomáš ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
Immersion of the body into the fluid creates additional effects which must be considered when designing the machines. Additional effects from the fluid influence the dynamic properties of the body. In this work the decrease of the natural frequency and the increase of the damping ratio during the gradual immersion of the body into the fluid are investigated. Diploma thesis is based on an experiment, which is performed on a series of flat strip steel components of various widths. The first three bending and first three torsion shapes of the free-hanging body are examined. Emphasis is placed on the influence of part width. In the next phase of the experiment, the influence of the proximity of the solid wall to the dynamic properties of the cantilever beam is examined. Further, the determination of the added density from the fluid is performed by modal analysis using the ANSYS software.
Determination of dissolved and undissolved air content in water
Svoboda, Richard ; Kmeco, Rudolf (referee) ; Habán, Vladimír (advisor)
This thesis describes the design and evaluation process of experimental measuring of the amount of bubbly air in water. The measuring principle is based on the assessment of speed of sound, which is dependent on the presence of air. Results were compared with the concentration calculated from the calibrated air flow through nozzles.
Sensitivity analysis of pressure-time method on measurement uncertainty
Červinková, Kateřina ; Himr, Daniel (referee) ; Habán, Vladimír (advisor)
The pressure-time method is one of two methods of measuring the flow rate on large hydraulic structures applicable to IEC 60041, which is based on the temporal integration of the measured pressure difference and the formation of a water hammer in a closed pipe. The aim of this master thesis is to perform a literature review of this method and to evaluate the flow rate of the measured data. Furthermore, the thesis deals with determination of the sensitivity of the evaluated flow rate to the weights of individual pressure sensors and to numerical modifying of the measured pressures. The first part is made using MS Excel. The flow rate is always evaluates with only one pressure sensor and it is compared with the original flow rate. There is research, how absence of the sensor has an impact on the evaluated flow rate. In the second part of the determination of the sensitivity of the evaluated flow rate, various encroachment (signal smoothing, noise, time delay, frequency band removal) are performed of measured pressure signal in Matlab. Various surrounding influences or sensors failures are simulated.
Pressure surge in the flowing gas simulation
Sedlmajer, Jakub ; Himr, Daniel (referee) ; Habán, Vladimír (advisor)
Creation of vacuum is very slow, energetically and technologicaly demanding process. Closing of valve is very simple and fast process which produces pressure surges when moving cylinder of fluid is stopped. The goal of this thesis is to find out, if it is possible to combine these processes. To reach this goal, 1D model of compressible gas flow and pressure surges in direct pipeline was made. Then follows experimental measurement evaluation and assessment of potential that the technology offers.

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