Heat transfer characteristics in a rotating AR=4:1 channel with different channel orientations at high rotation numbers

In order to reveal the effect of channel orientations on rotational heat transfer performance, this paper presents an experimental model of AR = 4:1 smooth rectangular channel. The stationary and rotational heat transfer characteristics of the channel are studied in the range of Re = 10,000–40,000 and Ro = 0–1.23 under the channel orientation of 90° and 135°, which represent the basic one and realistic one, respectively. The experimental results indicate that for the trailing wall, the 90° channel shows a typical large range enhancement of rotational heat transfer, while the rotational effect becomes negative in most areas at 135° case. As the rotation number exceeds 0.7, the heat transfer of the trailing surface is greatly improved by rotational effect in 90° channel. When the channel was orientated at 135°, the leading surface heat transfer is more sensitive to rotation under the low rotation number (Ro < 0.3), and 20%–30% worse than non-rotating cases. The averaged Nusselt ratios correlations under the channel orientation of 90° and 135° have been developed for further engineering applications.