Layout of lobed injector showing
gap through which fuel is injected.
This project involves modeling, design, construction, and testing
of a unique lobed
injector/burner. The shape of the burner is designed to generate
a large degree of streamwise vorticity with low a pressure drop.
This results in very rapid mixing of the fuel, which is introduced
through the slot, and the surrounding air. Near the injector exit
strain rates can be made high enough to suppress combustion, so
that burning occurs further downstream in a partially premixed mode.
This is seen to result in lower formation rates of thermal NOx
and products of incomplete combustion.
Both low speed as well as transonic mixing experiments utilized
acetone planar laser-induced fluorescence (PLIF) from which mixedness,
scalar dissipation rates, and strain rates have been extracted.
A combustion tunnel was used to study ignition delay and emissions
reduction using the lobed fuel injector. Numerical simulation of
a component of the mixing and reacting flow problem, the strained
fuel strip, has also been completed.
Recent work in this project has involoved transonic wind tunnel
testing of lobed injectors. PLIF was again used to image slices
of the flow at specific locations downstream of the injector. The
images have been processed and scalar dissipation and strain rates
have been measured at various Mach numbers. In coordination with
these experimental tests numerical simulations (using vortex elements)
were performed showing some striking similarities.
Mixing evolution due to lobed fuel
injector seen here in these images taken at different downstream
locations from the exit of the lobed injector (injectant illuminated
via acetone PLIF).
The four injectors tested, starting
from upper left going clockwise the injectors are: square,
half-circle rectangular, flat, and sine wave. Fuel is passed
through the centers of the injectors.
Images of the injectant from the
square wave lobed injector, situated at different downstream
locations, as determined from: (top row) acetone PLIF experiments
with the "actual" lobed injector shape, (middle row) computations
of the flow or vorticity distrubution with the actual lobed
injector shape as the input, and (bottom row) computations
of the flow or vorticity distribution with the lobed injector
shape that would be formed by an "ideal" EDM wire cut fabrication.
Photo of the fixture used for testing
the lobed injector at the UCLA/A2I2 Trisonic Wind Tunnel in
El Segundo, CA.
- Effects of Passive Fuel-Air Mixing and Emissions Control
via Lobed Injectors, Mitchell, M.G., Smith, O.I., and
A.R., AIAA Journal, Vol. 42, No. 1, pp.61-69, January,
Mixing Control via Lobed Injectors in High Speed Flow,
Majamaki, A. J., Smith, O. I., and Karagozian, A. R, AIAA Journal,
Vol. 41, No. 4, pp. 623-632, April 2003.
- Effects of Passive Fuel-Air Mixing Control on Burner Emissions
via Lobed Fuel Injectors, Mitchell, M. G., Smith, O. I., and
Karagozian, A. R., AIAA Paper No. 99-2400, 35th
AIAA/ASME/SAE/ASEE Joint Propulsion Conference, June, 1999.
- Numerical Simulation of Reactive Flows Associated with a
Lobed Fuel Injector, Selerland, T. and Karagozian, A. R.,
Paper 97F-108, Western States Section/The Combustion Institute
Fall Meeting, October, 1997.
- Ignition, Burning, and Extinction of a Strained Fuel Strip
with Complex Kinetics, T. Selerland and A.R. Karagozian, Combustion
Science and Technology 131, No. 1-6, p. 251, 1998.
- Burner Emissions Associated with Lobed and Non-Lobed Fuel
Injectors, M.G. Mitchell, L.L. Smith, A.R. Karagozian, and
O.I. Smith, 27th Symposium (Intl.) on Combustion,
- Numerical Simulations of a Lobed Fuel Injector, J. H.
Strickland, T. Selerland, and A. R. Karagozian, The Physics
of Fluids, Vol. 10, No. 11, pp. 2950-2964, 1998.
Measurements from a Lobed Fuel-Injector/Burner, M.G. Mitchell,
L.L. Smith, A.R. Karagozian, and O.I. Smith, Paper AIAA 98-0802,
AIAA 36th Aerospace Sciences Meeting, Reno. NV,
January 12-15, 1998.
Enhancement in a Lobed Injector, L.L. Smith, A.J. Majamaki,
I.T. Lam, O. Delabroy, A.R. Karagozian, F.E. Marble, and O.I.
Smith, The Physics of Fluids 9, pp. 667-678, March, 1997.
- Ignition Delay Associated with Strained Fuel Layers,
T. J. Gerk and A. R. Karagozian, 26th Symposium
(International) on Combustion, pp. 1095-1102, 1996