High-Resolution Heat Transfer Measurements and Crossflow Regulation in Narrow Impingement Cooling Channels with Divergent Geometries

The present study describes an experimental investigation into narrow impingement cooling channels with divergent geometries. The following analysis aims to clarify the influence that this particular form factor exerts on the heat transfer distribution, as well as on the traverse crossflow of the cooling passages. The research is based on the outcome of a numerical heat transfer optimization algorithm which indicates that divergent cooling channels present favourable heat transfer traits. Based on this remark, three impingement channels are investigated experimentally – two of them have divergent geometries and one has a rectangular (uniform) geometry. Heat transfer coefficients are resolved for those channels using a variation of the transient liquid crystal measurement technique, based on a triple layer of thermochromic liquid crystals. The experiments verify that divergent channels present crossflow with reduced momentum, and more equable jet velocity. These two factors lead to a more homogeneous spatial heat transfer distribution across the channels’ endplates.