Page 24 - AAA NOVEMBER - DECEMBER 2013 Online Magazine

FEATURE ENGINE DESIGN

Turbofan fuel injectors for GE’s
new LEAP engine will be printed
using 3D additive manufacturing
from cobalt-chromium alloy
powder. Each engine will use 19
injectors, each some 25% lighter
and five times more durable than
machined parts. Turbofan fuel
injectors for GE’s new LEAP engine
will be printed using 3D additive
manufacturing from cobalt-
chromium alloy powder. Each
engine will use 19 injectors, each
some 25% lighter and five times
more durable than machined parts.

GE’s LEAP engines
use some of the
latest technology
to pursue the holy
trinity of engine
design – more
power, longer
range, less fuel.

very expensive. CFM takes what it calls “a measured and fuel costs both bump up the airborne
“It is very important to constantly look approach to introducing” any new or cost, and the takeoff cost due to the fuel
for innovative solutions,” says Jamie Jewell, freshly refined technologies – it uses weight. Regional jets however need an
director of Strategic Communications an incremental rather than big rewrite engine that costs less in the first place, and
at CFM International, jointly working approach. “We take the time to mature has a best-in-class cyclic reliability along
out of the US and France. “CFM and its [new technologies] and prove that they are with a low cost, rapid cycle maintenance
parent companies, GE and Snecma, jointly reliable and durable before we ever install regime.
invest more than US$2 billion annually them in a customers’ engine,” she says. Then there are the environmental
in research and development. Many of “In the single-aisle market space, issues to consider. In a high-bypass ratio
the revolutionary technologies on the reliability is more important than fuel turbofan – the most commonly used jet
LEAP engine, including the carbon fibre efficiency. Our customers, on average, unit – both bypass and core flows produce
composite fan and the ceramic matrix operate 8 – 10 flights day with 30-minute thrust, which keeps noise down to a
composite in the high-pressure turbine, turnaround times. One delay early in the minimum. Current turbofans use around
have been in development for decades.” day and the entire schedule is blown,” she 80% bypass flow but this demands bigger
Rolls Royce tallies up its R&D spend at adds. housings, making installation a bigger
more than US$4.8 billion over the last five So the balance that the engine headache too. They also use less fuel
years. Despite the massive amounts of designers must face up to is a tricky one for a given thrust, but their sheer size
cash spent on research and development, – many of the design demands conflict, so means trickier maintenance demands. For
major leaps forward are not something the engineers need to trade off each against instance, the Rolls-Royce Trent family has
that happen frequently in the aerospace another to get the optimum blend that suits a range of fan diameters from the Trent
industry. It’s more of an inching slowly the purpose most closely. This, of course, 700 at 97.4 inches to the latest generation
forward process. changes with the type of aircraft and the at 118 inches.
The basic fact is that there is a direct route it is used on. Long range aircraft Any design is definitely a balance, with
correlation between weight and fuel need high fuel efficiency with low weight, the main technological challenges being
efficiency. According to Jewell, however, as payload revenues are most important the high mechanical integrity of fan blades
24 ASIAN AIRLINES & AIRPORTS NOVEMBER / DECEMBER 2013 WWW.ASIANAIRLINES-AIRPORTS.COM