Flow and heat transfer characteristics of hollow windward bend sandwich structure

In order to explore the flow and heat transfer characteristics of the hollow structure, the windward bend (WB) sandwich structure with high heat transfer and low flow resistance was hollowed to obtain the hollow windward bend (HWB) sandwich structure. The effects of hollow diameter ratio (d/D), thermal conductivity ratio and Reynolds number on the flow and heat transfer characteristics of HWB structure were studied numerically. The results showed that: (1) the hollow windward bend structure can reduce more weight at the expense of lower heat transfer loss. When d/D=0.5, the weight was reduced by 25%, but the Nusselt number was only reduced by 5.5%; (2) the thermal conductivity ratio of the HWB structure had a great influence on the ratio of the interstitial heat transfer to the end wall heat transfer. Increasing the thermal conductivity ratio, the interstitial heat transfer could increase more than the end wall heat transfer; (3) when d/D was small, the flow and heat transfer capacity of HWB structure and solid WB structure was basically the same at the same solid rate; when d/D increased to 0.9, the flow and heat transfer capacity of HWB structure was slightly stronger than that of solid WB structure.