•Validated CFD model was used to determine the temperatures of the water jet•The water jet cools down when passing the water nozzle•Main heating occurs in the region adjacent to the jet occupied by ...the carrier gas•Ice particles with d ≥ 0.5 mm should be used if water jet is not cooled•Ice particles with d ≥ 0.3 mm can be used if water jet is cooled
Ice abrasive water jet (IAWJ) technology uses ice particles instead of the mineral abrasives used in abrasive water jet (AWJ) technology. Since the thermal conditions are extremely important for the survival of the ice particles and their mechanical properties, the temperatures of the water jet and the adjacent air are analysed for different pressures and temperatures of the water upstream of the water nozzle and different nozzle orifice diameters. The temperature fields are calculated with a fully validated Computational Fluid Dynamic (CFD) model. The results show that the temperature of the jet core does not change significantly, but the adjacent air heats up considerably due to viscous heating; both are influenced by the water temperature and pressure upstream of the water nozzle. A low water temperature upstream of the water nozzle could significantly reduce the expected temperature of the ice particles exiting the cutting head. However, the use of a cold carrier gas such as nitrogen with a temperature of -196°C should not have a significant effect on the temperature of the ice particles inside the cutting head. It is recommended to optimise the geometry of the cutting head to reduce the travel time of the ice inside. If water cooling is not used, the ice particles should have a diameter of more than 0.5 mm. However, if cooling is used, particles as small as 0.3 mm in diameter can be used. The observed temperature conditions play a key role in the further development of IAWJ technology.
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To enhance the cleaning efficiency of the ice abrasive water jet (IAWJ), the nozzle in the jet structure was optimized. The cleaning effect of nozzle with different structural design is different. ...The design variables include the geometric parameters of the nozzle's structure and the flow process parameters of the jet. The maximum wall static pressure, outlet velocity and wash width are the optimization objectives. Based on the Optimal Latin Hypercube Sampling (OLHS) method, 50 sets of sample capacity were designed for simulation calculation. The parameter functions associated with the three objectives were fitted by MATLAB. The Competitive mechanism multi-objective particle swarm optimizer (CMOPSO) algorithm was used to optimize the nozzle to improve the cleaning effect, which was verified with the test results. The inlet pressure and outlet diameter are critical factors influencing the cleaning effect of the IAWJ. The maximum wall static pressure produced by the optimized nozzle is about 4.5% higher than that of the ordinary cosine nozzle. The cleaning effect of the optimized nozzle is 10% higher than that of the ordinary cosine nozzle, which is verified by the experiments. The optimization of the nozzle serves as a valuable reference for the nozzle structure design of the cleaning machine.
•The inlet pressure and outlet diameter of the nozzle are the most important factors on the cleaning effect of the ice abrasive water jet (IAWJ).•A three-objective optimization model of nozzle is designed based on the Competitive mechanism multi-objective particle swarm optimizer (CMOPSO) algorithm and Optimal Latin hypercube Sampling (OLHS) method.•The optimized nozzle cleaning rate can reach 90%.
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•First time observation of ice particles inside the high-speed water jet – Ice jet.•Ice particles sustained the acceleration by the water jet up to 7∙107 m/s2.•PLIF method was used to ...observe and measure the velocities of ice particles.•Erosion potential of single ice particles is comparable to that of mineral abrasive.
The Ice abrasive water jet technology uses cryogenically cooled ice particles instead of the mineral abrasive used in the Abrasive water jet technology. The aim is to avoid contamination of workpieces with mineral abrasives and to reduce the environmental impact of this technology. The ice particles are sucked into a high-speed water jet with speeds of up to 600 m∙s−1 using the Venturi effect. Direct observation of the process is very difficult due to the extreme operating conditions. We have clearly shown that at least some of the ice particles, which have cryogenic temperatures when entering the high-speed water jet, neither completely melt nor are completely crushed in contact with the jet. Further on, the erosion capability of ice particles was evaluated by blasting the aluminium and glass surfaces at two impinging angles and compared to garnet mineral abrasive, showing that ice particles have the potential to generate similar damage in the workpiece material as garnet. These findings pave the way for exploring the potential of abrasive waterjet technology in a wide range of new applications, such as food processing, medical implant and turbine blade manufacturing, and post-processing of parts manufactured with additive manufacturing technologies.
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