THERMAL MANAGEMENT AND ROTORDYNAMIC PERFORMANCE OF A HOT ROTOR-GAS FOIL BEARINGS SYSTEM. PART 2: PREDICTIONS VERSUS TEST DATA

Title
THERMAL MANAGEMENT AND ROTORDYNAMIC PERFORMANCE OF A HOT ROTOR-GAS FOIL BEARINGS SYSTEM. PART 2: PREDICTIONS VERSUS TEST DATA
Authors
Luis San Andres김태호류근
Keywords
THERMAL MANAGEMENT; ROTORDYNAMIC PERFORMANCE; HOT ROTOR; GAS FOIL BEARING; PREDICTIONS; TEST DATA
Issue Date
2010-06
Publisher
Proceedings of ASME Turbo Expo 2010
Abstract
Implementation of gas foil bearings (GFB) in micro gas turbines relies on physics based computational models anchored to test data. This two-part paper presents test data and analytical results for a test rotor and GFB system operating hot. A companion paper (Part 1) describes a test rotor-GFB system operating hot to 157ºC rotor OD temperature, presents measurements of rotor dynamic response and temperatures in the bearings and rotor, and including a cooling gas stream condition to manage the system temperatures. The second part briefs on a thermoelastohydrodynamic (TEHD) model for GFBs performance and presents predictions of the thermal energy transport and forced response, static and dynamic, in the tested gas foil bearing system. The model considers the heat flow from the rotor into the bearing cartridges and also the thermal expansion of the shaft and bearing cartridge and shaft centrifugal growth due to rotation. Predictions show that bearings’ ID temperatures increase linearly with rotor speed and shaft temperature. Large cooling flow rates, in excess of 100 L/min, reduce significantly the temperatures in the bearings and rotor. Predictions, agreeing well with recorded temperatures given in Part 1, also reproduce the radial gradient of temperature between the hot shaft and the bearings ID, largest (37°C/mm) for the strongest cooling stream (150 L/min). The shaft thermal growth, more significant as the temperature grows, reduces the bearings operating clearances and also the minimum film thickness, in particular at the highest rotor speed (30 krpm). A rotor finite element (FE) structural model and GFBs force coefficients from the TEHD model are used to predict the test system critical speeds and damping ratios for operation at increasing shaft temperatures.
URI
http://pubs.kist.re.kr/handle/201004/37587
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KIST Publication > Conference Paper
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