Abstract
The maximum output from large turbine generators is limited mainly by the temperature rise of the rotating field winding. Hydrogen at a pressure of several atmospheres is normally used to cool this winding by direct contact with the copper. Accurate knowledge of surface heat transfer coefficients is essential to ensure that the average winding temperature rise does not exceed the specified value.
A heat transfer rig was built to test full-size rotor coils in hydrogen and to compare actual with predicted copper temperatures. The construction of the rig is described, together with details of its operation and the various problems which had to be overcome. Tests were carried out on two designs of rotor coil. In one case the flow is laminar, and in the other it is turbulent. The test results are compared and the various heat transfer coefficients evaluated.
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