Ústav geoniky

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2017-10-04
17:58
Water Jet 2017 - Research, Development, Applications. Proceedings of the Conference on Water Jetting Technology
Klichová, Dagmar ; Sitek, Libor
Conference Water Jet 2017 – Research, Development, Applications coincides\nwith major changes in key technologies and economy which recently started to\nincrease pace.\nUpcoming electric mobility will strongly influence production technology in\nthe automotive industry leading probably to declining content of water jetting\nprocesses.\nThe continuing trend for automation will have an extreme impact on water jet\nbusiness. Merging robotic and data control systems with smart water jet tools will\nbe a demanding future task.\nThe need for energy saving remains unchanged and directs scientific focus on\nhigh efficient jetting, cutting and cleaning processes as well as tools. This is\nthe only way to gain substantial savings as efficiency of state of the art pump\nsystems is already on a very high level.\nTraditional technologies are moving towards marine applications. Subsea\nexploration becomes more and more important for basic raw material supply. Both\nmaintenance and decommissioning of vessels and offshore structures is already\na growing domain for special water jetting applications. Aquafarming substantially\ncontributes to supply a constantly growing human population with sea food\nwhereat water jet cleaning helps to keep high quality farming standards.\nAll these changes are linked up with associated HSE requirements. High\nefficiency, safe, ergonomic and reliable equipment as well as water treatment are\nkey factors for future developments.\nA strong scientific and engineering effort is required to meet these current and\nfollowing challenges. Water Jet 2017 Conference is organized by the Department of\nMaterial Disintegration of the Institute of Geonics.
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2017-10-04
17:58
Velocity measurements on continuous micro water jet using fluorescent PMMA seeding particles
Zeleňák, Michal ; Ščučka, Jiří ; Souček, Kamil
The paper deals with application of optical diagnostic techniques for velocity\nmeasurements of continuous micro water jet. The combination of Particle image\nvelocimetry, Particle tracking velocimetry, Laser induced fluorescence and\nShadowgraphy methods have been applied together with the use of fluorescent\nPMMA seeding particles. An experimental closed water circuit was designed with\na low-pressure water pump, and a series of experiments was conducted to\nmeasure the velocity of seeding particles in the water jet flow below the diamond\nmicro-nozzle outlet. The basic principles of the methods used in experiments are\nalso described.
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2017-10-04
17:58
Erosion capability of ultra-high-speed continuous waterjet and pulsating waterjet: the comparison
Sitek, Libor ; Hlaváček, Petr ; Klichová, Dagmar ; Trieb, F. ; Pude, F.
Advantages and possibilities of continuous ultra-high-speed waterjets (with\npressures of 600 MPa and more) when cutting metals are well known to\nthe professional public both from scientific studies and from practice. In addition\nto efficiency increased as water pressure increases and reduced water\nconsumption, abrasive consumption can also be reduced in the case of abrasive\nwaterjet. Ultra-high-speed waterjet technology allows not only to cut metal sheets\nwith pure water, but also allows cutting of harder materials such as ceramics.\nDespite the initial suspicion and technical problems associated with the reliability\nand sealing of some hyperpressure elements, high-pressure devices generating\nwater pressures around 600 MPa are now commercially available. However, no\ncomparison has been made so far concerning the efficiency of these jets with\nacoustically modulated high-speed pulsating waterjets using relatively low\npressures and higher water flow rates when eroding metallic materials.\nThe article compares cuts made by pure ultra-high-speed waterjet generated at\nhyperpressures (from 500 to 800 MPa) with erosive capabilities of pulsating\nwaterjets generated on the contrary at water pressures in the order of tens of MPa\non three metallic materials (stainless steel, mild steel and copper) using the same\njet hydraulic power.
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2017-10-04
17:58
Flow Field Analysis in Abrasive Head as Tool for High-Speed Abrasive Jet Cutting
Říha, Zdeněk ; Zeleňák, Michal
The article presents an analysis of the calculated flow field of water, vapor and\nabrasive particles in the inner geometry of a tool called the abrasive head using\na multiphase numerical flow model. The results of the above-mentioned analysis\nare compared with measured values of abrasive particle velocities at the outlet of\nthe abrasive head. For measuring of abrasive particle velocities, the PIV method\nwas used.
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2017-10-04
17:58
Properties and characteristics of recycled garnet abrasives for AWJ
Martinec, Petr ; Hlaváček, Petr ; Ruppenthalová, Lucie ; Sitek, Libor
The use of recycled garnet abrasive from sludge after cutting materials is a current\nproblem. The behavior of individual garnet abrasives in the AWJ process depends\non the geological origin of the garnets, which also affects all the material\ncharacteristics of the garnet recyclate. The parameters of the BARTON HPX80 and\nGMA 80 abrasive inputs and their recycled products were compared: mineralogical\ntype, apparent density, granularity, grain shape and mineralogical purity,\nmicrohardness data and the degree of damage to the garnet grains. All individual\nparameters of abrasives and their recyclates are reflected in the index of cutting\nefficiency of abrasive. The effect of abrasive material properties on cuttability of\nabrasives is synergistic. The new parameters in the evaluation of abrasives are\nmicro-hardness (brittleness criterion), specific surface and pore size distribution\n(internal grain damage criterion).
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2017-10-04
17:58
Evaluation of selected surface characteristics of CW004A copper disintegrated by PWJ
Lehocká, D. ; Klich, Jiří
Paper deals with copper CW004A surface characteristics evaluation after\ndisintegration by enhanced pulsating water jet. The main aim was identify and\ndescribe areas of pulsating water jet disintegration effects on material with using\ncircular nozzle diameter. 25 samples were disintegrated at change traverse speed\nv = 0.1 – 20 mm·s-1, for assessment of individual areas formation. Surface\ncharacteristics were evaluated based on surface roughness parameters Ra [μm],\nRz [μm], Rp [μm], Rv [μm], mass material removal Δm [mg.mm-1] and volume\nmaterial removal Vm [mm3]. Based on experimental investigation, three areas of\npulsating water jet effects on material were determined.
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2017-10-04
17:58
Evaluation of quality of cut surfaces created by abrasive water jet according to swiss standard SN 214001
Klichová, Dagmar ; Gurková, Lucie
The article focuses on the evaluation of the quality of cut surfaces created by\nan abrasive water jet (AWJ) according to the Swiss standard SN 214001 (2010).\nThe standard presents a quantified description of the texture of the cut. It defines\nnew parameters and methods of parameter measurements used in order to\ncategorize the cut surface in various quality levels Q. They are so far the most\ncommonly applied form of the qualitative description of the quality of the cut\nsurfaces created by the AWJ technology.

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2017-10-04
17:58
Influence of hydrodynamic nozzle wear on erosion effect of self-excited pulsating water jet
Klich, Jiří ; Říha, Zdeněk ; Foldyna, Vladimír
The article deals with the study of the wear of the hydrodynamic nozzle and its\ninfluence on the generation of a self-excited pulsating water jet (SPWJ). The nozzle\nwas monitored for the ability of the waterjet to erode the surface of the aluminum\nalloy EN AW 6060 at regular intervals.
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2017-10-04
17:58
Prospective of using pulsating water jet peening as a surface treatment process
Srivastava, M. ; Hloch, Sergej ; Tripathi, R. ; Chattopadhyaya, S. ; Dixit, A. R. ; Foldyna, Josef ; Hvizdoš, P. ; Fides, M. ; Adamčík, P.
This study focusses on exploring the effect of using Pulsating water jet technology\nas a surface treatment process. The AISI 304 plate samples were subjected to\nthe treatment process using circular nozzle at different levels of pressure and\nstand-off distance combination with variation of traverse speed. For evaluating\nthe effect of peening the surface residual stress was measured using the x-ray\ndiffraction technique. The results showed that the initial tensile residual stresses\non the surface were relieved and converted to compressive residual stress.\nThe present study shows that the new technology can be used as a potential\nsurface treatment method.
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2017-10-04
17:58
Abrasive water jet drilling of cooling holes in aeroengines: preliminary experimental study
Hlaváček, Petr ; Zlámal, T. ; Sitek, Libor ; Georgiovská, Lucie
This paper addresses an experimental investigation on the feasibility of using\nabrasive water jet (AWJ) for the drilling of small-diameter holes in aeroengines\ncomponents. These components are sprayed with ceramic thermal barrier coating\n(TBC). The required holes are typically 0.5 to 1 mm in diameter with a drilling\nangle of 30 to 90 deg. The parameters of the AWJ were varied to study their effects\non both quantitative and qualitative hole drilling parameters.
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