Dynamic modeling of vortex levitation

Vortex levitation can achieve non-contact handling by blowing air into a vortex cup through a tangential nozzle to generate a swirling air flow. In this paper, its dynamic characteristics are analyzed through dynamic pressure response, and a dynamic modeling is developed and verified experimentally. First, we observe the pressure dynamic response inside the cup by making the cup and the work piece relatively move sinusoidally at various frequencies. It is found that pressure transient response is very rapid so that pressure change follows the gap thickness change very well. Moreover, the annular skirt of the vortex cup entraps a thin air layer to give rise to a pressure hysteresis due to squeeze film air damping while the work piece repeating sinusoidal movement relatively to the cup. Next, according to those experimental observations, a spring-damper model is proposed by considering the lifting force caused by swirling air flow and the resistive force related to squeeze film air damping separately. Finally, the validity of the proposed model is confirmed by comparing the experimental results and analytical results in loading processes.