Effects of swirl on velocity-field uniformity in disk shape SOFC channel flow

Swirling flow behavior between two parallel disk shape plates was experimentally investigated with the aid of a particle image velocimetry (PIV). The experiment was performed at low Reynolds numbers (Re < 100) to simulate the practical operation in a disk shape planar-type solid oxide fuel cell (SOFC). To improve flow uniformity, we designed a new channel with circle involute shape current collectors. In the new channel, a swirling flow was generated and its velocity in a core region was kept at nearly constant value toward the channel exit. This trend was observed regardless of flow rates, and hence flow uniformity was achieved over the wide range of Reynolds numbers. This is because a flow passage consisting of two adjacent involute shape current collectors functions as a constat-area channel due to the geometrical property of the circle involute. In order to understand the above mentioned flow behavior, a swirling fluid motion in the channel with the circle involute shape current collector was investigated by using steady state Euler's equation of motion. We confirmed that the velocity component in the flow direction was dominant compared with that in the other direction and played primary role to maintain a swirling motion through the centripetal acceleration term.