Book on Aircraft Engine Lubrication/Oil System Design

[mastermechanic]

Hi everyone,

I need a textbook which either fully or partially focused on the lubrication and oil system design of gas turbines/aircraft engines. There are several books I have looked over but they simply introduces the main flow in the system and its components.

I need something which focuses on the design of the system, involves some calculations maybe case studies. In overall, I need something which guides me to the specific design points (altitude, take-off etc.) and some limit values.

I appreciate if you suggest me, thank you in advance !

 

[Baluncore]

Turbine Lubrication in the 21st Century (ASTM Special Technical Publication, 1407) Author(s): William R. Herguth, Thomas M. Warne, editors
Year: 2001 ISBN: 0803128851,9780803128859
Description:
Eight peer-reviewed papers cover:Current and future directions for some synthetic, ester- and hydrocarbon-based fluids. History of development and current state of base oil technology, including new processing methods for the production of more stable turbine oils. Performance advantages of using Group II and Group III base oils. Turbine oil quality and field application requirements. New technology for monitoring antioxidant oil analysis.

 

[berkeman]

I'll page @Flyboy since he has lots of practical experience working on jet aircraft. I don't know if he'll be able to help with the design angle, though.

 

[Baluncore]

It seems the engine manufacturers don't want to share this information.
Follow the bibliography and references to find more.

Lubrication Systems for Aircraft Gas Turbine Engines
By Ion Stiharu, Patrick Hendrick. ISBN: 9781119979654, 111997965X
Page count: 350. Format: Hardcover. Publisher: Wiley. 2017

Gas Turbine Lubrication Systems
https://blog.softinway.com/gas-turbine-lubrication-systems/

Chapter 8. Gearbox, Bearings and Lubrication.
https://www.gasturbineworld.co.uk/Small Gas Turbines 4 lubrication.pdf

Use of ceramic bearings for mainshaft support.
https://apps.dtic.mil/sti/tr/pdf/ADA067904.pdf

The Turbine Lubricating Oil System.
https://canteach.candu.org/Content Library/20042410.pdf

International Journal of Turbo & Jet-Engines.
https://www.degruyter.com/journal/key/tjj/html

The future of jet engine lubrication.
Berly McCoy, Contributing Editor | TLT Feature October 2021
Society of Tribologists and Lubrication Engineers.
https://www.stle.org/files/TLTArchives/2021/10_October/Feature.aspx

 

[256bits]

I need something which focuses on the design of the system, involves some calculations maybe case studies. In overall, I need something which guides me to the specific design points (altitude, take-off etc.) and some limit values.

If you are able to design and calculate the necessary lubrication flow for a bearing on any machine, then you are pretty much 100% there. You should really be looking at books of bearing loads and lubrication.
There is no magic involved with turbines.
Except
You are limited by the oil - ashless, no additives that when burnt cause sludge, and thin viscosity.
Any aircraft engine in for its running hour disassembly should appear clean.

Such things as takeoff and altitude have nothing much to with the design per se. One designs to keep the temperature of the oil below a certain value. Keeping the oil at accceptable levels while idling at the airport for extended periods of time on a hot tarmac could be just as much a limiting facture as cruising at 35000 feet.

For a fighter jet, one would probably consider designing for maximum power for extended periods of time, right from takeoff, contrary to commercial which dial back the thrust sometime after takeoff.

so you have your oil, you have your heat buildup in the bearings and the flow to each, thus the pump.
You just have to now consider the heat exchanger criteria to make it all work out.

 

[Flyboy]

I'll page @Flyboy since he has lots of practical experience working on jet aircraft. I don't know if he'll be able to help with the design angle, though.

Probably not in the way he's hoping. Lots of basic theory covered in A&P school, but most of the time it's a case of swap the filter after X flight hours, keep the oil topped off, and occasionally sample the oil for spectral analysis. However, lemme dig out the powerplant textbook and see what I can find...

Heyyyy, there's actually a free PDF of it. Awesome. Chapter 11 covers the lubrication system for turbine engines, but it's an interesting read in gneneral.

Anyways, again, kind of a top level overview of concepts. Lots of dry-sump systems in turbines, because it simplifies part swaps on the accessory gearbox which is basically always on the bottom of the engine. Usually it's well sealed anyways by bearings at the gearbox outputs, with spline drives running the accessories, but sometimes you have to swap out the bearings or seals because of a failure or leak. (I've got an old carbon seal off a Pratt & Whitney PW 306D1 from a swap lying around in a plastic bag somewhere, now that I think about it.)

You just have to now consider the heat exchanger criteria to make it all work out.

It's pretty common to use a fuel/oil heat exchanger. Even after heat soaking on the ground in Arizona in the summer, it's usually cool enough to work as a coolant for the oil, and at altitude, it definitely is cool enough. Warming the fuel actually provides a couple benefits, the biggest being the melting of any ice crystals in the fuel, which is absolutely a thing. I know of at least one airliner that was a write-off after the engines fuel starved on final because the fuel filters got clogged with microscopic ice crystals. But that's a different story.

I don't know how helpful it would be, but the most common brands of aviation oil are Mobil Jet II and Eastman (formerly BP) 2380 turbine oil, with the latter being the most common. (They're actually NOT compatible with each other and require full engine overhauls to switch between them, btw.)

I did find a tech data sheet for the 2380 oil, which covers some basic mechanical properties like density, kinematic viscosity, pour and flash points, etc. Even goes into how much it makes certain rubbers swell, which is really important. Mobil seems to be a little bit more cagey with their stuff, but I'm sure it's out there.

Hopefully this helps.