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Research in the area of pulsating water jets
Foldyna, Josef
A research in the area of pulsating water jets is carried out systematically in the Institute of Geonics AS CR, v. v. i., in Ostrava since 2000. The research was oriented primarily at the study of processes of generating and forming of pulsating water jets and their effects on various materials. The presented paper summarizes results obtained in the above mentioned areas during the period from 2000 to 2007.
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Calculation of natural frequency of high-pressure system
Foldyna, Josef ; Říha, Zdeněk ; Sitek, Libor
The paper presents results of numerical simulation of 3D, unsteady, turbulent flow of compressible water in a high-pressure system equipped with acoustic generator of pressure pulsations and its response to a pressure impulse. Results of numerical simulation are compared to the laboratory measurement of response of high-pressure system to a pressure impulse using dynamic pressure sensor placed upstream to the nozzle exit.
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Výzkum pulsujících vodních paprsků
Foldyna, Josef
he research on pulsating water jets at the Institute of Geonics ASCR in Ostrava was focused recently on the analytical and numerical modeling of the propagation of pressure pulsations in the high-pressure system with the integrated acoustic generator of pulsations, and the study of effects of the jet on various materials. Results obtained in above mentioned areas are summarized in the paper.
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Simulation of transmission of pressure pulsations in high-pressure system
Foldyna, Josef ; Říha, Zdeněk ; Sitek, Libor ; Švehla, B.
The paper presents results of numerical simulation of 3D, unsteady, turbulent flow of compressible water in a high-pressure system equipped with an acoustic generator. The generator vibrates at frequency of 20 kHz with amplitude of 6 µm. Acoustic waves (pressure pulsations), generated in water pressurized to 30 MPa and amplified by appropriately designed liquid waveguide, results in generation of very high velocity pulsations at the nozzle outlet. The influence of various geometrical configurations on acoustic wave propagation in the high-pressure system was simulated and results were verified by laboratory measurement of pressure pulsations upstream to the nozzle exit.
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Flow in the nozzle with moving wall
Foldyna, Josef ; Říha, Zdeněk ; Sitek, Libor
The paper presents simulation of 3D, unsteady, turbulent flow of water in the high-pressure nozzle device with moving wall. The wall performs rectilinear reciprocating motion with high frequency and very small amplitude that results in generation of very high velocity pulsations at the nozzle outlet. The pulsations lead to the break-up of continuous jet into regular slugs of water. The objective of the simulation was to verify whether dynamic meshes can be used to simulate above mentioned problem and satisfactory agreement of the simulation and reality can be obtained.
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