NDLI: A Simple Thermal Model of Bearings With Transient Effects

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Karleine, M. Justice Halliwell, Ian Jeffrey, S. Dalton
Copyright Year	2010
Abstract	In thermal management, system-level models provide an understanding of interactions between components and integration constraints — issues which are exacerbated by tighter coupling in both real life and simulation. A simple model of the steady-state thermal characteristics of the bearings in a two-spool turbofan engine has been described in previous work [1], where it was compared with a more comprehensive tribology-based simulation. Since failure is more likely to occur during transient rather than steady-state operating conditions, it is important that transient behavior is also studied. Therefore, development of models capable of capturing transient system-level performance in air vehicles is critical. In the current paper, the former simple model is used for the generation of a method to replicate the transient effects of heat loads within the lubrication system of a gas turbine engine. The simple engine model that defined the lubrication system is representative of a twin-spool, mid-size, high bypass ratio turbofan used in commercial transport. In order to demonstrate the range and versatility of the parametric heat load model, the model is now applied to the transient operation of a low-thrust unmanned aerial vehicle (UAV) engine, similar to that found on the Global Hawk. There are five separate bearings in the oil loop model and four separate oil sump locations. Contributions to the heat load calculations are heat transfer through the bearing housings and friction caused by station temperatures and shaft speeds, respectively. The lubrication system has been simplified by applying general assumptions for a proof-of-concept of the new transient parametric model. The fuel flow rate for the fuel-cooled oil cooler (FCOC) is set via the full authority digital electronic control (FADEC) in the transient engine model which is coupled to the parametric heat load model. Initially, it is assumed that total heat transfer from the bearings to the oil correspond to oil temperature changes of 150–250°F (83–139°C). The results show that successful modeling of the transient behavior on the thermal effects in the bearings of a gas turbine engine using the MATLAB/Simulink environment have been achieved. This is a valuable addition to the previous steady-state simulation, and the combined tools may be used as part of a more sophisticated thermal management system. Because it is so simple and scalable, the tool enables thermal management issues to be addressed in the preliminary design phase of a gas turbine engine development program.
Sponsorship	International Gas Turbine Institute
Starting Page	379
Ending Page	388
Page Count	10
File Format	PDF
ISBN	9780791843963
DOI	10.1115/GT2010-23537
e-ISBN	9780791838723
Volume Number	Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Education; Electric Power; Manufacturing Materials and Metallurgy
Conference Proceedings	ASME Turbo Expo 2010: Power for Land, Sea, and Air
Language	English
Publisher Date	2010-06-14
Publisher Place	Glasgow, UK
Access Restriction	Subscribed
Subject Keyword	Temperature Bearings Model development Industrial lubrication systems Fuels Modeling Engines Vehicles Design Gas turbines Turbofans Temperature effects Unmanned aerial vehicles Failure Steady state Flow (dynamics) Stress Transients (dynamics) Heat Simulation Friction Thermal management Heat transfer Thrust Matlab Tribology
Content Type	Text
Resource Type	Article

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