Nozzle Design for Low-Pressure Micro Abrasive Waterjet Blasting via CFD Simulations

Waterjet technology has been extensively used in machining processes since 1970’s, and in the last years it has evolved to a precision machining tool for micro workpieces, namely micro abrasive-waterjet blasting (μAWJB); nevertheless, as a finishing process to remove micro-burrs it has not been yet developed. Our experimental studies on low-pressure μAWJB showed that conventional nozzles which are used for micro abrasive air jet blasting are subject to clogging at the mixing chamber. In this study, the venturi principle is exploited in order to obtain a novel nozzle design which will not lead to the clogging problem. The factors are considered as follows: the volumetric flow rate, the contraction–expansion ratios, the length of the cylindrical throat and the location of the attached (side) pipe. Various geometries are considered and a number of numerical simulations are performed to analyze these factors so that a nozzle which is suitable for low-pressure μAWJB can be constructed in light of the numerical results. The nozzle which is chosen in accordance with the numerical findings is proven to be operational with experimental studies.