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Load analysis of open rotor aircraft engines
2009 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The pressures on the airline industry today due to environmental issues are high, and as the fuel prices go up the demand for more efficient engines increase. In the 1980’s a technology with counter rotating fans was tested, and the results were impressive in terms of fuel efficiency. Nonetheless, due to fuel prices going down, the engines never came to production. But the technology was proven and today the need for efficient engines has dusted off this concept again. Volvo Aero is part of the development of demonstrator Open Rotor engines and there is a need for an understanding of the loads the engine is subjected for during different flight conditions. The purpose of this thesis has therefore been to get an understanding of the loads on the engine and its mounts. Furthermore the loads on specific parts that are of interest for Volvo Aero have been investigated. To accomplish this, mechanical layouts of the engines have been drawn to get an overview of the structure. Two different mounting configurations have been proposed, with one of them being suggested as a suitable system for the types of engines examined in this thesis. The fans are driven by either a counter rotating power turbine or a planetary gearbox. In the case of the power turbine, a performance analysis has been carried out to investigate the loads that are present in such a configuration, especially axial loads. The engine concept incorporates large diameter fans and gyroscopic effects are therefore of interest. The results show that gyroscopic effects are of small importance for the engine and its mounts due to the counter rotating nature of the fans. However, the gyroscopic moments are large in the structures and shafts connected to the fans and cannot be neclected. The loads in the shaft bearings differ according to their position and function, but they will all have to withstand high loading during Fan Blade Off. The turbine performance analysis was quite extensive and since the correct design and other parameters are not known, the results should be seen as guidelines. The axial loads in the turbines are sensitive to changes in mass flow and pressure distributions, and the loads in the bearings are difficult to estimate. Due to the shape of the channel used in this thesis, these axial bearing loads are large. As a result, reverse thrust might involve difficulties.

Place, publisher, year, edition, pages
Keyword [en]
Keyword [sv]
URN: urn:nbn:se:ltu:diva-56208ISRN: LTU-EX--09/157--SELocal ID: cfc39b6e-6349-4f12-9b12-ad2c97e49e6bOAI: diva2:1029595
Subject / course
Student thesis, at least 30 credits
Educational program
Space Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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