Abstract
Submicron particles transported by a Laval-type micronozzle are widely used in micro- and nano-electromechanical systems for the aerodynamic scheme of particle acceleration and focusing. In this paper, the Euler–Lagrangian method is utilized to numerically study non-spherical submicron particle diffusion in a converging–diverging micronozzle flow field. The influence of particle density and shape factor on the focusing process is discussed. The numerical simulation shows how submicron particle transporting with varying shape factors and particle density results in different particle velocities, trajectories and focusing in a micronozzle flow field. The particle with a larger shape factor or larger density exhibits a stronger aerodynamic focusing effect in a supersonic flow field through the nozzle. In the intersection process, as the particle size increases, the position of the particle trajectory intersection moves towards the throat at first and then it moves towards the nozzle outlet. Moreover, the influence of the thermophoretic force of the submicron particle on the aerodynamic focusing can be ignored. The results will be beneficial in technological applications, such as micro-thrusters, microfabrication and micro cold spray.
Highlights
In recent years, there has been a considerable increase in the attention of many researchers in the field on MEMS techniques, such as micro-thrusters, microfabrication and micro cold spray [1]
After the gas flow expands along the micronozzle in the divergent
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Summary
There has been a considerable increase in the attention of many researchers in the field on MEMS techniques, such as micro-thrusters, microfabrication and micro cold spray [1] In these studies, the most important micro-device is a Laval-type micronozzle, which has an appropriate geometry, including a convergent section, a throat and a divergent section to induce particle acceleration via a supersonic propulsive gas. Akhatov et al [8] studied the flow focusing of particles and verified that the velocity of the particle beam can be accelerated to 100 m/s in a contracting subsonic nozzle through experimental and numerical simulation methods. Kudryavtsev et al [3] mentioned aerodynamic focusing and conducted a numerical study on the micro particle flow in plane-shaped, axisymmetric and three-dimensional supersonic micronozzles with the Euler–Lagrangian method.
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