Prediction and Measurement of Heat Transfer in a Switched Reluctance Generator
Abstract
The report is an experimental investigation of heat transfer convective film coefficients for a simulated high-speed electromachine rotor. The rotor geometry was matched to that of a switched-reluctance machine (SRM) for a USAF-funded integrated power unit (IPU) turbogenerator design, with an operating speed of 55 krpm. The experimental test of cooling a preheated rotor was achieved by convection to air that flowed axially through rotor pole gap cavities. The tests included a series of insulated rotors, with each rotor having a uniquely exposed (from insulation) rotor pole surface so to help determine the film coefficient for that specific surface. The coefficients for each surface, and the overall rotor surface film coefficient, were inferred by the cooling rates of the test rotors at given rotor speeds and axial airflow rates. The test rotors, with 4.3 in. maximum diameter, were operated at a speed range of 5--30 krpm, with an axial airflow range of 0.036--0.073 kg/sec. (Test rig limitations prevented higher rotor test speeds.) The resultant convective film coefficients are given in terms of Stanton and Nusselt numbers correlated to Reynolds number and velocity ratio of axial airspeed to rotor tip speed. Experimental variations from earlier analytical estimates were within 10--15 %.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1998
- Accession Number
- ADA381472
Entities
People
- Eugene Himes
- John J. Schauer
Organizations
- University of Dayton