|
|
Research on waterjet in Institute of Geonics of the AS CR from 1990 to 2006
Vašek, Jaroslav
The paper is continuation of an article published in the proceedings of the conference "Water Jet 2011 - Research, Development, Applications”. By 1990, the work is briefly described in the article (VAŠEK 2011). The follow-up work carried out in the period 1990 - 2006 is the subject of this article. The paper gives a brief overview of the author's participation at the World Mining Congress in Beijing (1990), a collaboration with CNR Canada, CNR Cagliari (Italy), the organization of international conferences GEOMECHNICS 91, 93 and 96. The cooperation with University of Missouri Rola (hereinafter UMR) USA, Cornerstone Technologies and Pennsylvania Micronics, cooperation within the project EU-Inco Copernicus (1995 - 1999) and the project of Grant Agency of the Academy of Sciences of the Czech Republic (hereinafter GAAV) "Mechanical breakages and disintegration processes of coal and rock - theoretical aspects, applications, outlook” (2001-2006) are also presented.
Fulltext: content.csg -  DOC
Plný tet: UGN_0398600 - DOC
|
|
|
Removal of polyurea spray coatings from the surface of cement concrete by water jet technology
Ščučka, Jiří ; Bódi, Z. ; Hlaváček, Petr ; Klich, Jiří ; Martinec, Petr ; Foldyna, Josef
The paper is focused on the removal of polyurea spray coatings from the surface of cement concrete by the water jet technology. A series of experiments was conducted to disintegrate a defined polyurea spray coat layer on the surface of cement concrete tiles using different configurations of the water jet system. The results of these experiments have confirmed that the continuous water jet was highly effective in removing the spray coat, causing no damage to the concrete substrate underneath. The partial experimental results have also indicated that this process can be used to produce an anti-skid finish on polyurea spray coatings applied onto horizontal structures.
Fulltext: content.csg - DOC
Plný tet: UGN_0398599 - DOC
|
|
|
Research on effects of pulsating water jets on concrete
Sitek, Libor ; Bodnárová, L.
An article briefly presents results achieved during laboratory and in-situ tests of removing surface layers of concrete exposed to various environments using several types of high-velocity water jets commonly used in the rehabilitation praxis or advanced water jets the use of which is expected in the near future. The effects of pulsating jets were always compared with classical continuous jets under identical or similar working conditions.
Fulltext: content.csg - DOC
Plný tet: UGN_0398582 - DOC
|
|
| |
|
| |
|
|
Effects of pulsating water jet on materials with variously modified surface
Klich, Jiří ; Klichová, Dagmar ; Hlaváček, Petr
The paper deals with determination of erosion effects of pulsating water jet impinging the surface of aluminium alloy samples treated by various techniques (rough and fine milling, planing and rolling). The influence of the initial surface topography on the final topography of the sample exposed to pulsating water jet was investigated. Erosion of surface layer was analysed and discussed with respect to the traversing velocity of the jet. It was found, that properties of the initial surface have a significant impact on the final topography. Degree of erosion of the surface was determined by the measurement of surface parameter Ra.
Fulltext: content.csg - DOC
Plný tet: UGN_0398577 - DOC
|
|
| |
|
|
The measurement of the velocity of abrasive particles at the suction part of the cutting head
Foldyna, Josef ; Zeleňák, Michal ; Klich, Jiří ; Hlaváček, Petr ; Sitek, Libor
To be able to optimize the design of the abrasive cutting head using numerical simulation, it is necessary to gather as much information about processes occurring in the cutting head as possible. The development of the numerical model of processes occurring in the abrasive water jet cutting head during the process of creation and forming of abrasive water jet is currently in progress at the Institute of Geonics in Ostrava. The verification of the model requires, among others, to determine the behaviour of abrasive particles at the input of the cutting head. Therefore, the visualisation of abrasive particles at the input using various parameters of abrasive jet and its subsequent analysis was performed using shadowgraphy (backlighting) technique and the results are presented in the paper.
Fulltext: content.csg - DOC
Plný tet: UGN_0398575 - DOC
|
|
|
Pulsed liquid jet generated by pulse multiplication technique
Dvorský, R. ; Sitek, Libor ; Sochor, T.
First theoretical papers summarizing the high mechanical energy cumulation when high-speed drops impacting the solid surface as a result of the water hammer effect have been known since 1960’s. Heymann has demonstrated that pressure maximum in the impact of a spherical drop of a liquid is several times higher than the presupposed maximum for the classical water hammer effect. The latter maximum pressure itself exceeds the mere stagnation pressure of the continuous jet many times hereat. When developing devices for pulse jet generation a new generalization of the classical water hammer theory for high pressures has been implemented. Based on this the new patented principle of “pulse multiplication” has been formulated. The pulse multiplier is the source of high-pressure pulses with 100% depth of modulation of liquid jet discharge velocity that allows increasing the jet disintegration effect significantly without the abrasive material application.
Fulltext: content.csg - DOC
Plný tet: UGN_0398574 - DOC
|
|
| |
guest ::
