Aeronautics and astronautics – Aircraft power plants
Reexamination Certificate
2000-02-25
2001-07-24
Jordan, Charles T. (Department: 3644)
Aeronautics and astronautics
Aircraft power plants
C055S306000, C060S039092
Reexamination Certificate
active
06264137
ABSTRACT:
TECHNICAL FIELD
This invention relates to inlets for auxiliary power units mounted in airplanes.
BACKGROUND OF THE INVENTION
Airplanes often have an on-board auxiliary power unit to provide electrical power and compressed air to various systems throughout the airplane. When the airplane is on the ground, the auxiliary power unit is the main source of power to drive the environmental control systems, air driven hydraulic pumps, and the starters for the engines. Auxiliary power units may also provide pneumatic and electric power during flight.
Campbell et al, U.S. Pat. No. 5,655,359 shows a typical arrangement for mounting an auxiliary power unit in the tailcone of an airplane. Referring to
FIG. 1
, an intake duct
30
extends between an intake opening
32
in the exterior surface
16
of the tailcone and the air inlet of the auxiliary power unit
10
. The intake duct
30
defines an airflow passage
34
through which the auxiliary power unit
10
draws in air. An inlet door
33
is pivotally attached to the airplane
14
at the aft end of the opening
32
. When the inlet door
33
is open, air flows in the direction of the arrows under the influence of the auxiliary power unit itself (ground operation) or the airstream of the airplane and the auxiliary power unit (flight operation).
These inlet doors also referred to as scoops and typically comprise a closing wall contoured to the fuselage and have channel forming side
5
plates contoured to the side walls of the inlet against which they fit upon closing. An example of such an inlet door is disclosed in Vanderleest et al, U.S. Pat. No. 4,418,879.
It has been found that during ground operation with air entering the inlet from all directions that the air flow around the side walls creates corner vortices or distortions. These vortices or distortions flow through the intake duct
30
and into the compressor inlets of the auxiliary power unit. Because air in the vortices is spinning, the leading edge of the compressor blades rotate through the vortices the incidence of the air on the leading edge flips resulting in losses and a reduction in compressor performance.
Accordingly, there is a need for an inlet door assembly that does not generate corner vortices during ground operation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an inlet door assembly that does not generate corner vortices during ground operations.
The present invention meets this objective by providing an air inlet assembly for bringing air to an auxiliary power unit mounted in the compartment of an aircraft. The assembly includes a duct extending from an intake contoured to conform to the to the aircraft fuselage to an exit coupled to the inlet plenum of the auxiliary power unit. A first door hingeably mounted to the aft side of said intake and moveable from an open position to a closed position where said first door lies flush against intake, said first door having a closing wall and two side walls and a second door hingeably mounted to the forward end of said intake, said second door having a plate with two inwardly extending walls, each of said inwardly extending walls hinged to one of said side walls so that the second door rotates with said first door.
During ground operation air that would have swirled around the side walls of the first door thus generating inlet corner vortices are now blocked by the side walls of the second door.
These and other objects, features and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 2694357 (1954-11-01), Lee
patent: 2695074 (1954-11-01), Kelly
patent: 2944631 (1960-07-01), Kerry et al.
patent: 3109610 (1963-11-01), Quenzler et al.
patent: 3421296 (1969-01-01), Beurer, Sr.
patent: 3952972 (1976-04-01), Tedstone et al.
patent: 4174083 (1979-11-01), Mohn
patent: 4346860 (1982-08-01), Tedstone
patent: 4397431 (1983-08-01), Ben-Porat
patent: 4418879 (1983-12-01), Vanderleest et al.
patent: 4899958 (1990-02-01), Horikawa
patent: 5655359 (1997-08-01), Campbell et al.
patent: 5694763 (1997-12-01), Amelio et al.
patent: 5697394 (1997-12-01), Smith et al.
Desmond, Esq. Robert
Honeywell International , Inc.
Jordan Charles T.
Steele George L.
LandOfFree
Inlet vortex bustor and ice protector for auxiliary power units does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Inlet vortex bustor and ice protector for auxiliary power units, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inlet vortex bustor and ice protector for auxiliary power units will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2555827