A numerical simulation on the flow field of the novel pneumatic actuator system realised by micro-EDM

This paper presents a numerical simulation of the flow-field on a one-dimensional pneumatic actuator. Unlike conventional actuators, this model uses dynamic pressure instead of friction to drive a slider. The objective of this simulation is to examine the detail of the flow-field under the slider as well as the influence of its levitation on the horizontal transportation. Secondary vortices to be formed under the slider tend to cause an instability of the slider movement. To further assure a stable transportation of the slider, there being no secondary vortex formed in the gap is desirable, and which will be achieved by narrowing the gap width. However a too narrow gap in turn causes a significant increase of flow impedance and thus can sacrifice the horizontal transportation. Here two cases with gap width 100 /spl mu/m and 50 /spl mu/m were investigated. With gap width 50 /spl mu/m, there was no secondary vortex formed, however the horizontal transportation was greatly sacrificed. In contrast, with gap width 100 /spl mu/m, several secondary vortices 1 to 2 times the size of the gap width were formed. However the horizontal driving force was about eight times larger than that in the case of gap width 50 /spl mu/m.