Analysis and modelling of particle velocities in micro-abrasive air jet

A study of the flow characteristics in micro-abrasive jets

“…It can be seen that within the measured axial range from nozzle exit to about 24.5 mm downstream, the axial velocity profiles demonstrated firstly an acceleration stage in which the velocities continued to increase outside the nozzle, then a transition stage where the change of particle velocities is minimum, and a final stage where the particles decelerate. This is consistent to the theoretical study of particle velocities by Li et al [1]. If the nozzle is not long enough for particles to gain the velocity close to that of the air, the particle will have an extended acceleration stage outside the nozzle.…”

“…In this section, mathematical models for the abrasive particle velocities in an AAJ are developed, using the same approach presented in Li et al [1]. The particle velocity through a nozzle is modeled by considering particle mass and the drag force from the air stream.…”

“…Abrasive jet micromachining (AJM) has been considered as one of the most appropriate micromachining technologies for hard and brittle materials, such as ceramics and semiconductors [1,2]. Owing to its various distinct advantages, such as negligible heat affected zone, small cutting forces, high machining versatility and high flexibility, AJM has been used in fabricating electronic devices and micro-fluidic channels in recent years, where damage-free micro-part features are required.…”

“…Furthermore, such information is required to understand kerf characteristics and formation process and optimize the jetting parameters so as to optimize the jet performance for AJM. For these purposes and for verifying theoretical studies, different methods have been used to measure the particle velocity in AAJ, such as high-speed photography and double-flash exposure technique [10], rotating doubledisk [11][12][13], laser Doppler anemometry (LDA) [14,15] and particle image velocimetry (PIV) [1,[16][17][18].…”

“…In spite of the various reported investigations, there is a significant dearth of understanding of the jet and particle dynamic characteristics, typically velocity, for micro-abrasive jets in the velocity range applicable to AJM [1]. This paper presents an experimental study of particle velocities in micro-AAJ by using PIV measurements.…”