sure compressor. The work at Glenn,
conducted with General Electric,
targets loss mechanisms and interac-
tion effects across the highly loaded
stages of the compressor. Building on
earlier ERA testing of a single-stage
unit, the last set of tests will evaluate
a three-stage compressor integrated
with engine bleed oftakes and an inlet
flowpath. “The reason this is so hard to
do is, as you go to higher front-loaded
compressors, the flow relative to the
blades gets highly supersonic across
multiple blade layers. This generates
very strong shocks and a lot of inter-
action between blade rows,” says Ken-
neth Suder, chief of Turbomachinery
and Turboelectric Systems Branch
Propulsion Div. at NASA Glenn.
The test unit is a precursor of GE’s
GE9X for Boeing’s upcoming 777X.
“So we have taken a legacy piece of
hardware and tried to understand
where the losses are coming from,”
says Suder, who was speaking at the
American Institute of Aeronautics
and Astronautics SciTech conference
earlier this year. Testing is set for the
third quarter of the year. “We have
done computational fluid dynamics
(CFD) analysis and we still believe
we’re going to get a 2.5% reduction in
fuel burn,” he adds.
NASA is also working with Pratt &
Whitney toward the final integrated rig
test this summer of a second-genera-
tion UHB propulsor that will evaluate
the combined performance of a ver-
sion of the robust bi-metallic fan used
in the geared turbofan, with advanced
fan exit guide vanes and a shorter inlet.
The work, which aims to cut noise by
15 EPNdb and fuel burn by up to 9%,
builds on more than 200 hr. of earlier
wind tunnel work that “verified me-
chanical performance is consistent with
what the CFD predicted,” says Suder.
Pratt & Whitney and United Tech-
nologies Research Center are also
working with NASA’s ERA program on
tests of a combustor concept aimed at
reducing NOx emissions during land-
ing and takeof (LTO) by 75%. Earlier
tests indicated potential for an 88%
reduction in LTO NOx for a lean-lean
combustor concept “but there were
some issues with CO 2 as well as ef-
ciency at idle conditions,” says Suder.
As a result, the final phases will focus
on studying auto ignition, flame stabil-
ity and acoustic resonance as well as
ability to operate on a 50/50 mix of jet
and alternate jet fuel mixture.Two ITDs concerning noise reduc-
tion are also underway. One is study-
ing techniques for cutting the cumu-
lative noise of flaps and landing gear
by more than 6 EPNdb, while another
is evaluating both the nose and drag
issues associated with integrating
UHB engines in noise-shielding posi-
tions very close to the upper surface
of a hybrid wing body. The latter
evaluation is being conducted with
Boeing at the 40 X 80-ft. test facil-
ity at NASA Ames Research Center
in Mofett Field, California, operated
by the U.S. Air Force’s Arnold Engi-
neering Development Complex. Key
performance targets for the test in-
clude a cumulative noise reduction
of 42 EPNdb and a 50% reduction in
mission fuel burn.
NASA forecasts that if ERA tech-
nologies are incorporated into the
worldwide fleet from about 2025 on-
ward, they would cumulatively reduce
up to 88 billion gal. of jet fuel use by- “I believe the various technical
contributions of the project will have
a lasting impact on the aviation com-
munity long after we are finished with
ERA,” says Collier. c
50 AVIATION WEEK & SPACE TECHNOLOGY/MARCH 30-APRIL 12, 2015 AviationWeek.com/awst
CIVIL AIRCRAFT ADVANCESTests of Boeing’s Hybrid Wing Body at high angles-of-attack and sideslip are
underway in the 40 X 80-ft. test facility at NASA Ames Research Center.NASA