CO2 Emissions and SFC.

[Scott Duch]

Hey people. I'm am undergraduate student studying Aeronautical Engineering and currently have an aerospace design project to undertake. We are working in groups of 4 people each with our areas of expertise. I have been seleted for the propulsion and apu sections. We have to do market research into the aviation industry and work to a given technical specification. This specification is for a regional airliner. We can tweak the specification a little, but our group has choose to stick with regional flight, something similar to Flybe and the Dash 8Q-400.
For the project, I have been weighing up the option for either a turboprop or turbofan configuration and decided to go for the former. I have got various dimensions, weights, SHP and costs (for cost analysis at the end of the project). I have shortlisted various turboprop engines but would like to make a comparison between each to include in my report. I have the details to do power/weight ratio but can't seem to find any data about emissions from the engines nor can I get my hands on specific fuel consumption data. I have emailed the likes of Pratt & Whitney and Rolls Royce but no reply and this was late January when I emailed them.

If anyone could supply a website(s) with this kind of information on emissions and fuel consumption it would be greatly appreciated. You will be appropriatly referenced. Thanks. ;)

[Genghis the Engineer]

sfc data is readily available from Janes - I find the paper version much more user friendly than the electronic version, but you should have that in the library. The back part of each volume has the engine data.

Emissions are in reality really complex, but most simplistic analysis tends to work on a fixed figure of 3.15 tonnes CO2 (http://www.eea.europa.eu/publications/EMEPCORINAIR4/B851vs2.4.pdf) per tonne of fuel burned.

In reality, there are other chemicals in fuel emissions, and for example there is a trade off within engine configuration of CO2 versus what are called the NOxy compounds (NO, NO2, NO3...) and scientists who study this stuff are still spending a lot of time trying to decide what combination is least hazardous to the ozone layer.

There is a Royal Aeronautical Society specialist group called Greener by Design, and if you search on their work, you'll find a lot of published work - in particular I'd look at their various conference papers. Or look at the air traffic manual I linked above in my second paragraph, and the references in that.

There will be a series of other trade-offs you want to consider if you do this properly. A long haul aircraft will "tanker" a lot of fuel, which puts the mean weight (and especially weight at take-off an initial climb) up, and thus increases fuel burn and so all emissions. Short-haul flying usually comes out, comparatively, less damaging per passenger mile. Also look at the relative drag profiles of a slower turboprop versus a faster turbofan. The other major factor, although not well understood yet by current science, is that mixing of greenhouse gasses across the tropopause is limited - so greenhouse gas emissions from a turboprop, which is likely to spend most of its time in the troposphere, is likely to be in most analysis less damaging than a similar quantity emitted from a turbofan that spends most of its life in the lower stratosphere.

Also, whilst I appreciate that Glasgow is a bit out of the way, you might want to try a tool called "Google" that works well for us in the South. 30 seconds with it found the reference above, and quite a few others. Google Scholar is even more useful for academic work since it finds you the journal papers that carry most ivory-tower-cred.

G

[bearfoil]

What you frame in your request resists some simple conclusions re: the purpose of your paper. I get that you are either trying a clean sheet proposal, or are seeking to collect data from work that has already been done. Hundreds of times.

All design flows from a goal of some description.

Is your goal to capture strictly a "Green Design"? Or does it also have something to do with SFC, meaning fiscal drivers, and requisite financial limits??

Aviation is always a compromise of hundreds of "Important" considerations. If you want semi clean sheet, PM Keesje. He has some remarkable concepts going on at any given moment.

If you want Fuel specifics re: design engineering of Turbine powerplants, PM Turbine D. Fuel tankering and logistics: Pinkman.

Your first task, and perhaps the simplest, is to index your two salient parameters in your proposal.

CO2, and SFC. Where you position the one or the other in your Title drives the discussion, No??

Oxygenated Fuels, there's the ticket..........

best of luck,

bear