Convective Heat Transfer in a Rotor–Stator System Airgap With a Centered Natural Suction of Fluid

The present work relates to an experimental study of the local convective heat transfer over the rotor surface in the air-gap of a discoidal rotor–stator system. This configuration is of interest namely, in electrical machines or tubomachinery. Following precedent studies obtained for a single rotating disk or a closed (but unshrouded) rotor–stator system, an air suction comes through the stator and enters the air-gap in this particular work. Determination of Nusselt numbers is based on the use of infrared thermography. The influence of the suction is discussed for an interdisk dimensionless spacing interval, G ranging from 0.01 to 0.16 and for a rotational Reynolds number, Re between 30,000 and 5,16,000. Results shows that the suction could locally provide better cooling than in the closed rotor–stator and in the single disk configurations, even if the main influence is a decrease in the convective heat transfer.