CFD Analysis in a Non-Contact Holder

Abstract

There are many devices that use air flow characteristics. Recently an electric fan without propeller using air jet flow and a vacuum cleaner using swirling air flow have been developed by Dyson Ltd. Furthermore, as one of the applications of such air flow, a non-contact holder that can hold a body such as a work piece, disc etc., using low-pressure region generated by air flow without contact was developed by a Japanese company. Some bodies such as work piece are brought without contact with the holder. The mechanism to hold them is explained by Bernoulli’s theorem. However, systematic research has not been done in the present stage and the effect of the geometry of the non-contact holder on the holding force is not clear. In this paper, we calculated the flow in a non-contact holder and obtained the force to hold a body by CFD analysis. The effect of the deflector and inside geometry of the holder on the velocity and pressure distribution, and holding force is investigated. The deflector is a device fixed with the holder to increase the holding force using low-pressure region. CFD was done using both incompressible and compressible flow, and k-ε turbulent model was used. The calculated pressure distributions of a simpler model of the holder are compared with the previous experimental results to confirm our calculation method. The design policy of a non-contact holder is discussed based on the calculated results of velocity and pressure distributions and holding force. Consequently we show that the deflector is very useful to obtain high holding force and the concept to design the non-contact holder is required to get the holding force according to the weight of the body and to achieve high efficiency.