Heat transfer of compressed air flow in a spanwise rotating four-pass serpentine channel

Convective hear transfer of compressed airflow in a radially rotating four- pass serpentine channel is investigated experimentally in the present study . The coolant air was compressed at 5 atmospheric pressure to achieve a hig h rotation number and Reynolds number simultaneously. The main governing pa rameters are the Prandtl number the Reynolds number for forced convection, and the rotation number for the Coriolis-force-induced cross-stream seconda ry flow and the Grashof number for centrifugal buoyancy. To simulate the op erating conditions of a real gas turbine, the present study kept the parame ters in the test rig approximately the same as those in a real engine. The air in the present serpentine channel,ras pressurized to increase the air d ensity for making up the low rotational speed in the experiment. The air fl ow was also cooled to increase the density ratio before entering the rotati ng ducts. Consequently, the order of magnitude of Grashof number in the pre sent study was the same as that in veal operating conditions. The local hea t transfer rate on the walls of the four-pass serpentine channel are correl ated and compared with that in the existing literature.