Measurement of Windage Losses and Temperature Distribution for a High Speed Composite Rotor in a Stator Assembly at Low Air Pressures

Abstract

With the advancements in composite technology several innovative applications present themselves that involve high-speed composite rotors spinning in a stator assembly. As rotational speeds and rotor tip speeds increase, these rotors must operate in low air pressure environments to minimize windage losses and thermal effects of being at high speed for long durations. Accurately predicting this windage loss for a specific geometry and operating conditions is very important for a proper design. It is also very important to know the relative heat distribution that is seen by the rotor and stator from this windage loss. Analysis tools to date do not have a coupled link that calculates windage loss and a resultant thermal distribution to the rotor and stator surfaces. This paper presents the design and fabrication of a test setup to measure the total windage loss and temperature distribution from a high-speed composite rotor in a stator structure. Rotor speeds up to 40,000 rpm and rotor tip speeds up to 900 m/s with pressure ranges from 0.1 torr to 10 torr were operating parameters during the testing. The paper will also present experimental data obtained during the testing. Experimental data obtained during the testing will be used to evaluate new analysis methods for predicting the windage loss and thermal distribution in new high-speed rotor applications.

Investigation of windage splits in an enclosed test fixture having a high-speed composite rotor in low air pressure environments

“…To understand the effect of operating high-speed rotors in a partial vacuum, a series of spin tests, consisting of a composite rotor which is capable of being spun up to 900 m/s, have been designed and tested [5,6]. These spin tests were designed to simulate pulse alternator rotor-to-stator conditions.…”

“…Windage test data for high-speed rotors in partial vacuum environments are generally not available. The University of Texas at Austin Center for Electromechanics (UT-CEM) has designed and conducted a series of composite rotor spin tests to measure the windage losses and temperature distributions of a test setup at high rotor speeds and low air pressures [5,6]. The intent of the windage tests is to validate the windage loss predictions [7] and investigate how the air-gap windage is distributed between the rotor and stator under the test conditions.…”