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Measurement and analysis of abrasive particles velocities in AWJ
Zeleňák, Michal ; Foldyna, Josef ; Martinec, Petr ; Cárach, J. ; Gurková, Lucie ; Nováková, Daria
Abrasive water jet (AWJ) is a progressive technology commonly used in many industrial applications. Potential of this technology is high and research in the field of optimal geometry design of an injection system has not been completed yet. New designs of the injection cutting head based on numerical simulation of the flow provide important information about processes occurring during the formation of AWJ. Detailed knowledge of velocities of abrasive particles during the abrasive water jet generation is vital for the verification of the numerical model. The aim of the experimental work was to test the applicability of the LIF (Laser Inducted Fluorescence) technique combined with the PTV (Particle Tracking Velocity) processing algorithms to analyze particle velocities at the output of the focusing tube. The combination of commonly used water pressures with abrasive mass flow rate was tested and the obtained results of abrasive particles velocities are presented in this paper.
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Erosion effects evaluation of pulsating water jet on brass EN 12164
Lehocká, D. ; Klich, Jiří ; Foldyna, Josef ; Hloch, Sergej ; Cárach, J.
The objective of this experiment is to verify an assumption that with decreasing value of feed rate, mass v material removal Δ of brass EN 12164 during cutting by pulsating water jet is increased, and to seek the mass erosion curve course depending on the change of feed rate v [mm·s-1]. The selected observed parameter was evaluated in two units of Δ [mg·s-1] and Δ [mg·mm-1]. Two mutually related experiments were carried out. In the pilot experiment, the curve originating at hydraulic power output of 15 kW was evaluated that was achieved in combination of nozzle diameter d [mm] and pressure p [MPa] - d/p [mm/MPa] = 1.0668/52; 1.3208/39; 1.6002/31. After the pilot experiment, another experiment followed in which a particular range of feed rate values v = 0.2 - 8 mm·s-1 was selected. This resulted in finding that different courses of erosion process exist for mass material removal expressed in the form of curve Δ [mg·s-1] and Δ [mg·mm-1], depending on feed rate v [mm·s-1].
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Hydro-abrasive machining of rotating workpieces from graphite and aluminium alloy
Cárach, J. ; Hloch, Sergej ; Klich, Jiří ; Hlaváček, Petr ; Klichová, Dagmar
The paper compares the quality of machined surface of graphite and aluminium alloy by abrasive water jet using the focusing tube with a diameter of df1 = 0.5 mm and df2 = 0.78 mm. The machining was carried out using the technology of rotating workpiece disintegration by abrasive water jet. Abrasive tangential water jet was used to carry out the experiment (water pressure p = 400 MPa). Workpieces were clamped in the rotating chucking appliance with rotation frequency n = 300 min-1. The change in focusing tube diameter caused the change in values of roughness parameters, and also caused the change of resulting shape of workpieces. Values of roughness parameters were measured using the MicroProf FRT optic profilometer.
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