Heat transfer measurement in a rotating cooling channel with staggered and inline pin-fin arrays using liquid crystal and stroboscopy

Endwall heat transfer in the stationary and rotating cooling channels with pin-fin arrays (inline and staggered pattern) were experimentally measured by wide band liquid crystal. The temperature measurement was performed with the stroboscopic photography to capture the reflected color from the liquid crystal coatings on the rotating object. A detailed calibration was performed to quantify the uncertainties in the liquid crystal measurement from the stroboscope frequency, flash duration, and viewing angle. The Reynolds numbers ranged from 5000 to 20000 and the rotation numbers ranged from 0 to 0.52. This measurement technique provided detailed heat transfer variations caused by the distinct secondary flow patterns from pin-fin and rotation. Results showed that the heat transfer from the staggered array was 25-30% higher than the inline array in the stationery channel. The rotation led to unsymmetrical heat transfer distributions along the spanwise direction. The heat transfer variation caused by rotation was more noticeable for the inline array, and the heat transfer in the rotating channel was more than 50% than that in the stationary channel.