|
|
Engine
Halon Replacement
| Nacelle
Simulator |
|
|
Beginning in 1995,
work began on a simulator located at the FAA W. J. Hughes Technical
Center. The project has spanned two project engineers and seen
residence in two different structures on the facility. The simulator
still remains under construction, but its current
status is forever changing.
The nacelle
simulator is a flow pathway having a front end to condition
and supply air, a test section, and an exit to eject effluent
from the entire device. The entire simulator
is roughly 90 feet (27 m) long. The front end to the test section
accounts for 50 feet (15 m), the test section approximately 20
feet (6.1 m), and the exit completes the balance of the length.
The front end is composed of a supplying centrifugal blower,
a heat exchanger, a stream straightener, and 32 feet (9.8 m)
of 36-inch (91-cm) diameter duct. The test section consists of
two concentric cylinders, having 24-inch (61-cm) and 48-inch
(122-cm) diameters respectively. The annular volume of the compartment
is approximately 100 cubic feet (2.8 m3). The test section also
houses obstructions for clutter, equipment to support spray and
residual fire scenarios, and hardware to deliver gaseous fire
suppressants. The exit of the simulator consists of ducting to
pass the effluent from the test section exit up and out of the
building.
The front end of
the test section contains hardware to provide air flow as prescribed
in the MPSE. The air flow is provided by a centrifugal blower.
Downstream from the blower, the flow then passes through a transition
section and enters a heat exchanger housing. At this point, the
flow departs the exchanger, passes through a grill structure,
and finally enters a 36-inch (91-cm) diameter duct.
From this duct,
the flow enters the test
section; the heart of the simulator. This section contains
hardware to provide a spray or residual fire scenario and receives
the fire suppressant. The fire
scenarios are located approximately 130 inches (330 cm) from
the inlet of the test section. The spray
fire scenario is located in the upper part of the annular
cross section. A fuel delivery nozzle, a 2-inch (5.0-cm) tall
baffle, electrodes to ignite the spraying fuel, and a local hot
surface work integrally to provide the fire. In the lowest portion
of the annular cross section lies a residual
fire scenario. A pan with an ability to maintain constant
fill level during a fire event, a 2-inch (5.0-cm) tall baffle,
electrodes to ignite the pan contents, and a local hot surface
combine to provide the residual fire threat. The last component
in the test section to complete the simulation is the fire
suppression system. The bottle storing the gaseous agent
straddles the test section inlet diffuser. It is a unit on loan
from the USAF, courtesy of the Aircraft Survivability group located
at Wright Laboratories, Wright-Patterson AFB, Ohio. The unit
is a right circular cylinder capable of varying volume and temperature
control. The unit is plumbed into the test section roughly 36
inches (91 cm) from the inlet to test section. Currently, the
agent is delivered into the test section through four 0.500-inch
( 1.3-cm) outside diameter tubes near the section wall penetrations.
The agent is introduced in counter flow fashion within the test
section.
Gas concentration
analysis is achieved by a Pacific Scientific HTL/Kin-Tech Halonyzer II, serial number 001. The
configuration
of the analyzer probes(sampling lines) within the nacelle
simulator catches the concentration profile of the fire extinguisher
discharge using all 12 channels. They are arranged in three rings,
each having 4 probes apiece. Based on in-house configurations,
the device capabilities and limitations follow :
- The analyzer can
record gaseous agent distributions when mixed with air. These
agents include the gaseous agents recommended by the IHRWG.
- Simultaneous 12
channel recording of the gas distribution profile to a resolution
of 10 Hz.
- The analyzer can
not be used during live fire testing.
Additional simulator
process control, temperature, and pressure profiles are achieved
with in-house computer/ analog-to-digital hardware and software.
For Further
Information Please Contact :
Doug Ingerson
GO BACK
LAST UPDATED
ON 7/26/99
|