Experimental study of heating fluid between two concentric cylinders with cavities

In this paper, we are concerned with the heating fluid in the annular space between two concentric cylinders where the inner cylinder with cavities is rotated and the outer cylinder is at rest. The effects of cavities of the inner cylinder on the heating fluid and the cavitation behavior are examined. We measured the flow rate, rotating speed of rotor, friction torque, temperature rise and pressure drop between inlet and outlet of this device. The flow rate of water ranged from 0.42×10−4 to 4.59×10−4 m3/s at the inlet. The friction torque and the quantity of heat of the inner cylinder with cavities were larger than the case of no cavities, and they increased as the rotating speed of inner cylinder increased. The efficiency was close to about 1 as the rotating speed of inner cylinder increased. The behavior of cavitation in the cavity on the surface of inner cylinder was discussed.