Flow and Heat Transfer in Curve Channel with Cosinoidal Wave Wall Structure

Abstract

Heat transfer rate in curve channel decreases with channel curvature since the secondary flow turns weak with the decrease of centrifugal force. In this paper, the periodical wave wall structure is introduced into curve channel for improving heat transfer rate in the curve channel with small curvature. The channel radius is not constant anymore but varies periodically based on a cosinoidal function. Three-dimensional numerical investigation was carried out to explore the flow and heat transfer characteristics in the curve-wave channel, and the effects of wave frequency and average curvature on the heat transfer performance were analysed. The results show that the heat transfer rate in curve channel can be improve up to 95.50% due to the periodical wave wall structure, while the friction factor increases by 53.94%. The effect of periodical wave wall structure gets obvious with the increase of Re. Heat transfer in curve-wave channel can be further enhanced by increasing wave frequency of channel wall. In addition, the effect of wave wall structure on heat transfer is dependent on the overall curvature of curve-wave channel and stronger for larger-curvature curve-wave channel. The performance factors of all the curve-wave channels are almost above 1, indicating that this structure can be used as an economic passive heat transfer enhancement method.