In this study, we investigated the value of the loss coefficient, ζ{sub}23, at the exit of the rotor ventilation ducts when air coolant flows from the rotor ventilation ducts to the rotor-stator air gap by measuring the distribution of staticpressure on the surface of the rotor and the stator and on the wall of the cooling duct of air cooled generators, by using a scale water model. Protuberant type rotor wedge was proposed and they performed much better than the flat type of rotor wedge forventilation cooling. From the experimental results, for the protuberant type rotor wedge, the fluid can flow from the exit of the rotor cooling duct into the air gap with a small pressure loss, since the fluid near the rotor surface is separated from therotor surface by the triangular protuberance and the static pressure above the exit of the cooling duct is less than that in the rotor cooling duct. The experimental results of the pressure loss and the results of numerical analysis which will be reported in another paper, were in good agreement.
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