Analysis of levitation using porous media

Non contact handling can be achieved by supplying air beneath the work piece by means of porous pad. In this study, several metal sintered porous media are used to conduct experimental and theoretical investigations on the basic characteristics concerned with levitation. It is confirmed that flow rate characteristics of the test porous media can be represented in terms of permeability and inertia coefficients as defined in Darcy-Forchheimer regime, and therefore the supply flow rate can be estimated according to the supply pressure considering that downstream is open to the atmosphere. Experimental investigation on the pressure distribution in the gap formed by the porous surface and the work piece is conducted, and it is clear that the pressure distribution varies as the gap thickness changes. The lifting force can be calculated according to the pressure distribution when the height of the gap is adjusted to a certain value, and correspondingly, with the supply flow rate fixed, it is verified that lifting force increases as the gap thickness becomes smaller and decreases as the gap thickness becomes larger. Furthermore, it is observed that there exists an apparent difference between the forward and backward stroke in pressure response due to the squeeze effect.