Nusselt Number Measurement of Air Flow between Grooved Rotor and Stator of a Generator

In this article, turbulent flow heat transfer in the air gap between rotor and stator of a generator under nonhomogeneous heat flux is studied experimentally. The rotor consists of four symmetrical triangular grooves. The stator surface is smooth and does not include any grooves. The relative heat flux between the rotor and the stator is 1 to 3. Temperature and heat flux are measured locally at three axial and two angular positions of inner and outer surface. The pressure drop of air flow through the air gap is also measured. In this work, the axial Reynolds number and rotational velocity of the rotor ranges are 4000<Rez<30000 and 300rpm<ω<1500rpm, respectively. The results indicate that increasing the rotational velocity causes the rotor and stator heat transfer coefficient to increase considerability and the respective value to the rotor is higher than that to the stator. In addition, the rotational velocity causes the air flow to be developed sooner.