AIRCRAFT FUEL CELL AIR SUPPLY ANTI CONTANIMATION SYSTEM

Abstract

The invention defines a combined system of sensor(s), control logic, air intake and contaminant deflector for a fuel cell system mounted on an aircraft, which will detect contamination in the free air flow surrounding the aircraft and if excessive contamination is detected will activate the contaminant deflector to protect the fuel cell system from contamination, damage and power loss. The system ensures constant speed of the aircraft by adjusting the power of the fuel cells to compensate any change in aircraft drag and adjusts the speed of any connected compressors to maintain and achieve necessary changes in power and compensation for any air pressure losses the system creates.

Claims

1. An aircraft air intake channel anti-contamination system configured to protect the air intake channel from airborne contaminants in an air flow around the aircraft, the air intake channel being configured to deliver air from the air flow to a fuel cell of the aircraft, and the system including: a sensor configured to detect contaminants in the air flow; a contaminant deflector deployable from a retracted position to a deployed position in which it disrupts the air flow to thereby deflect contaminants away from or out of the air intake channel; and a controller programmed to move the contaminant deflector to the deployed position in response to detection by the sensor of contaminants in the air flow.

2. The aircraft air intake channel anti-contamination system according to claim 1, wherein the air intake channel is configured to deliver air from the air flow to a compressor of the fuel cell of the aircraft, and the controller is programmed to increase a speed of the compressor in response to deployment of the contaminant deflector to the deployed position.

3. The aircraft air intake channel anti-contamination system according to claim 1, wherein the controller is programmed to increase a set power output level of the fuel cell in response to deployment of the contaminant deflector to the deployed position.

4. The aircraft air intake channel anti-contamination system according to claim 3, wherein the air intake channel is configured to deliver air from the air flow to a compressor of the fuel cell, and the controller is programmed to control a speed of the compressor in response to the set power output level of the fuel cell.

5. The aircraft air intake channel anti-contamination system according to claim 1, wherein the contaminant deflector is biased to either the deployed position or the retracted position.

6. The aircraft air intake channel anti-contamination system according to claim 5, comprising an actuator controllable by the controller to: hold the contaminant deflector in the retracted position or the deployed position, respectively; and to release the contaminant deflector to allow it to move to the deployed position or the retracted position, respectively, in response to detection by the sensor of contaminants in the air flow.

7. The aircraft air intake channel anti-contamination system according to claim 1, comprising one or more vortex-generating devices at one or more outer edges of the contaminant deflector.

8. The aircraft air intake channel anti-contamination system according to claim 1, wherein the air intake channel is configured to deliver air from the air flow to the fuel cell of the aircraft via an intake air flow, and in the deployed position the contaminant deflector is configured to either: (i) disrupt the air flow to thereby deflect contaminants in the air flow away from the air intake channel; or (ii) disrupt the intake air flow to thereby deflect contaminants out of the air intake channel.

9. The aircraft air intake channel anti-contamination system according to claim 1, wherein in the deployed position the contaminant deflector projects outwardly from an external surface of the aircraft upstream of the air intake channel into an external air flow across the external surface, to thereby disrupt the external air flow and deflect contaminants in the air flow away from the air intake channel.

10. The aircraft air intake channel anti-contamination system according to claim 9, wherein in the retracted position the contaminant deflector is integrated into the external surface of the aircraft.

11. The aircraft air intake channel anti-contamination system according to claim 1, wherein the air intake channel is configured to deliver air from the air flow to the fuel cell of the aircraft via an intake air flow, and in the deployed position the contaminant deflector obstructs the air intake channel to define a secondary outlet channel via which the intake air flow is diverted to a secondary outlet at an external surface of the aircraft.

12. The aircraft air intake channel anti-contamination system according to claim 11, wherein in the deployed position the contaminant deflector defines a secondary intake channel having a secondary air inlet, the secondary intake channel being configured to deliver a secondary intake air flow from the secondary air inlet to the fuel cell.

13. The aircraft air intake channel anti-contamination system according to claim 1, wherein in the deployed position the contaminant deflector projects outwardly beyond an external surface of the aircraft.

14. An aircraft comprising a fuel cell, an external surface, an air intake channel in fluid communication with the external surface and the fuel cell, and an aircraft air intake channel anti-contamination system configured to protect the air intake channel from airborne contaminants in an air flow around the aircraft, the air intake channel being configured to deliver air from the air flow to a fuel cell of the aircraft, and the system including: a sensor configured to detect contaminants in the air flow; a contaminant deflector deployable from a retracted position to a deployed position in which it disrupts the air flow to thereby deflect contaminants away from or out of the air intake channel; and a controller programmed to move the contaminant deflector to the deployed position in response to detection by the sensor of contaminants in the air flow.

15. The aircraft as claimed in claim 14, wherein the air intake channel comprises an inlet at an external surface of the aircraft and wherein the air intake channel directs an air flow from the inlet to a compressor configured to provide compressed air to a fuel cell or other propulsion system.

16. The aircraft as claimed in claim 14, wherein the contaminant deflector is positioned upstream of an inlet of the air intake channel.

17. The aircraft as claimed in claim 14, wherein the contaminant deflector is within the air intake channel.

18. The aircraft as claimed in claim 14, wherein when in the deployed position the contaminant deflector disrupts the air flow by directing it outwardly away from an external surface of the aircraft to thereby carry airborne contaminants away from an inlet of the air intake channel.

19. The aircraft as claimed in claim 14, wherein the contaminant deflector comprises an impingement surface which, in use, the air flow impinges against in the deployed position and wherein in the deployed position the impingement surface is arranged at an angle to an external surface of the aircraft to thereby urge the air flow away from the external surface and, in the retracted position the impingement surface is generally aligned with, or contiguous with, the external surface.

20. A method of protecting an air intake channel of an aircraft from airborne contaminants in an air flow using an anti-contamination system comprising a sensor configured to detect contaminants in the air flow, a contaminant deflector deployable from a retracted position to a deployed position in which it disrupts the air flow to thereby deflect contaminants away from or out of the air intake channel; and a controller programmed to move the contaminant deflector to the deployed position in response to detection by the sensor of contaminants in the air flow, the method including the step of: by the controller, responding to detection of contaminants in the air flow by the sensor by deploying the contaminant deflector to the deployed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0055] FIG. 1 illustrates a system view of an embodiment of the invention;

[0056] FIG. 2 illustrates an embodiment of the invention where the air contamination deflector is integrated within the air intake duct;

[0057] FIG. 3 illustrates an embodiment of the invention where the air contamination deflector is positioned separately and upstream of the air intake;

[0058] FIG. 4 illustrates an embodiment of the invention which creates favourable vortices to reduce contamination ingress;

[0059] FIG. 5 illustrates the control logic of operation of the system; and

[0060] FIG. 6 illustrates the relationships of the contamination mass, air flow, aircraft attitude, deflector size and position and intake flows.

DETAILED DESCRIPTION

[0061] In general terms, FIG. 1 shows an overview of the invention, which in preferred embodiments provides an air intake 10 that connects to and supplies air to a turbo-compressor or compressor 11, which in turn supplies air to a fuel cell 12 in the aircraft. The aircraft has mounted on its exterior surface in a suitable location one or more contamination sensor(s) 13 to detect contaminants in the air flow over the exterior surface. The contamination sensor 13 could be an infrared type sensor or an equivalent device, or a combination of different sensors incorporating different sensing technologies to sense different types of contamination.

[0062] If the presence of air contaminants is detected by the contamination sensor 13 then the contamination sensor 13 will deliver a signal to the PCU (Propulsion Control Unit) 14, or similar logic controller. In response to receiving the signal, the PCU 14 will trigger an actuator 15 to release a contamination deflector 16 such that it positions itself in the air flow within or upstream of the air intake 10 to deflect the majority of contaminants in the air flow away from progressing further into the air intake and consequently from entering the compressor 11 and fuel cell 12.

[0063] When the PCU 14 is triggered by the contamination sensor 13 to actuate the contamination deflector 16 then it will also communicate to the compressor 11 to increase the speed of the compressor. This increase in speed serves to compensate for the loss of ram air and other pressure losses due to the deployment of the contamination deflector 16, which disrupts the flow in the air intake 10. This system is intended to be operable for all operation phases of the aircraft, including both flight phases and ground phases.

[0064] FIG. 2 shows an embodiment of the invention where the intake 10 has an inlet at the leading edge of a part of the aircraft 100, and the contamination deflector 16 is integrated as a sub-element of the air intake 10. In the upper part of the illustration the contamination deflector 16 is shown in its retracted position, while in the lower part of the illustration the contamination deflector 16 is shown in its deployed position. Arrows illustrate how air travels through the air intake 10 in each of the retracted position and the deployed position.

[0065] The air intake 10 provides a channel connecting the inlet with the compressor 11, and the contamination deflector 16 is mounted down-stream of the inlet and up-stream of the compressor 11. Optionally an air filter 102 may be included in the flow path between the inlet of the air intake 10 and the fuel cell(s). In the illustrated embodiment of FIG. 2 the air filter 102 is located immediately before the compressor 11.

[0066] The contamination deflector 16 in this embodiment comprises first 16a and second 16b elements. The first elements 16a form part of the air intake 10 internal surfaces when the deflector 16 is in the retracted position. The second elements 16b are independent of the air intake 10, and only interact with the flow path when the contamination deflector 16 is activated to its deployed position in which it projects into the air flow in the air intake. In preferred embodiments the second elements 16b form part of the external surface of the aircraft 100.

[0067] When the contamination deflector 16 mechanism is activated to its deployed position it it will connect the inlet of the air intake 10 to an adjacent air channel 101 that is otherwise not in communication with the air intake or the external air flows around the aircraft. In the deployed position the first 16a and second 16b elements form a continuous barrier to divide the adjacent air channel 101 into a secondary outlet channel and a secondary inlet channel downstream of the secondary outlet channel. Thus, air flowing from the inlet of the air intake 10 is diverted along the secondary outlet channel to a secondary outlet, so that contaminants within that air flow are diverted away from the compressor 102. Clean air is drawn into the secondary inlet channel from a secondary air inlet to the compressor 102.

[0068] A projecting part 16c of the contamination deflector 16 will be created by the positioning and kinematics of the second element 16b, such that the deflector 16 projects beyond the external surface of the aircraft into the external air flow in the deployed position. This will ensure that the contaminated air flow diverted from the air intake 10 will be projected beyond the external surface of the aircraft. This flow in combination with the projecting part 16c will create a low contamination air space 104 which the compressor or turbo-compressor 11 can safely draw air from with a lowered contaminant content into the secondary inlet channel.

[0069] The contamination sensor 13 is built into a separate part of the aircraft where it has the most likelihood to effectively detect the onset of a contaminated air flow and is unaffected by the operation of the contamination deflector 16. In the illustrated embodiment the contamination sensor 13 is fitted up-stream of the contamination deflector 16.

[0070] A preferred embodiment of the invention is shown in FIG. 3, where the contamination deflector 16 and air intake 10 are mounted on a side surface of the aircraft 100. In the upper part of the illustration the contamination deflector 16 is shown in its deployed position, while in the lower part of the illustration the contamination deflector 16 is shown in its retracted position.

[0071] In this embodiment the air intake 10 is shown in the form of a scoop that projects from the aircraft 100. Alternatively, the invention may be used in conjunction with any projecting air intake types or flush mounted air intake types such as a NACA inlet. Scoop type air intakes 10, such as that illustrated in FIG. 3, may optionally be fitted with an aerodynamic fairing 103.

[0072] The air intake 10 feeds air from an inlet to a compressor 11 and may optionally have an air filter 102 included up-stream of the propulsion system. The anti-contamination system has a contamination sensor 13 fitted onto a separate part of the aircraft where it has the most likelihood to effectively detect the onset of a contaminated air flow and is unaffected by the operation of the contamination deflector 16. In the illustrated embodiment the contamination sensor 13 is fitted up-stream of the contamination deflector 16.

[0073] Should the contamination sensor 13 detect sufficient contamination present in the air flow then, via the control logic enacted by the PCU 14, it will cause the actuator 15 to release the contamination deflector 16 from a retracted position to a deployed position where it projects into the air flow sufficiently to deflect the contaminated airflow beyond the air inlet 10, whilst accounting for the suction effects of the compressor 11. Important to the effective working of the system is the air space 104 between the contamination deflector 16 and the air intake 10 which must be sufficient that the compressor 11 has sufficient contaminant free volume to suck air from this protected space behind the contamination deflector 16 taking into account factors such as the mass of the contaminant, aircraft velocity and aircraft attitude.

[0074] FIG. 3 also illustrates the retracted position of the contamination deflector 16, in which there is an unobstructed and clean air flow into the air intake 10. Also illustrated is the retraction trough 105 in which the deflector 16 is concealed in the retracted position so that it appears integrated into the external surface of the aircraft.

[0075] FIG. 4 shows the deployment of a contamination deflector 16 forward of an air intake 10, where in preferred embodiments the contamination deflector 16 has additional aerodynamic features 201 such as a pair of vortex generators that, when the contamination deflector 16 is deployed into the air flow in the deployed position, cause air vortices 202 to be generated. When the contamination deflector 16 is retracted into the retraction trough 105, then these aerodynamic features 201 are also retracted flush with the surface of the aircraft 106 and do not act on the air flow external to the aircraft. When the contamination deflector 16 is deployed to the deployed position, however, the air vortices 202 generated by the aerodynamic features 201 create energy in the air flow in the form of an air vortex 202 that acts from the end of the aerodynamic features 201 and thus positions the contaminated air flow further away from the air intake 10 than the basic geometry of the contamination deflector 16. These air vortices 202 have a high energy to entrain any air contamination within them and thereby reduce the possibility that the contamination can enter the air intake 10. These air vortices 202 are so positioned that in all aircraft flight attitudes, including pitch up and yaw, that the air vortices will not impinge on the throat of the air intake 10. The air vortices therefore prevent contamination from being communicated into the attached fuel cell system.

[0076] FIG. 5 describes the logic of the preferred embodiment of the invention where the aircraft speed of the aircraft the invention is fitted to is maintained constant throughout the deployment of the anti-contamination system. The logic is particularly designed to mitigate the impacts of the deployment of the contamination deflector 16, and later its retraction when it is no longer needed to be deployed. In this logic when the contamination sensor 13 detects that excessive contaminants are present in the free air flow the signal will be picked up and processed by the PCU 14. The PCU 14 in response to this signal will then trigger the deployment of the contamination deflector 16 which, due to its deployment, will alter the air flow around the aircraft and into the air intake 10.

[0077] In its deployed state the contamination deflector 16 will add a known drag increment to the aircraft, and hence the PCU 14 will also increase the set power level required from the fuel cells 12 to increase the propulsive thrust to the aircraft to thereby maintain the aircraft's airspeed at a constant level. The deployment of the contamination deflector 16 will also cause a known a reduction in the air pressure and reduction in air flow through the compressor 11 into the fuel cells 12. In some circumstances the stoichiometric ratio and pressure drop may be such that an insufficient air flow is provided to the fuel cells 12 to achieve the new set power level. The PCU 14 would therefore in this instance also increase the speed of the compressor 11 to raise the air pressure and increase the flow of air into the cathodes of the fuel cells 12 to enable the new power setting. In this case the PCU 14 may also take feedback from existing sensors on the fuel cell system, such as air mass flow and generated voltages which would allow the PCU 14 to adjust the inputs to the compressor 11 and fuel cells 12 due to any variations due to state of degradation of the fuel cell 12 or similar.

[0078] At the point that the contamination sensor 13 indicates that the level of contaminants in the air flow fall below the designated acceptable level, then the PCU 14 will trigger the actuator 15 to retract the contamination deflector 16 and will reverse any power setting changes and changes in the compressor 11 speed made to account for the return of the standard flow into the air intake 10, thereby once again maintaining the aircraft speed constant.

[0079] FIG. 6 highlights some of the key relationships to ensure that the contamination deflector 16 and any aerodynamic features 201 are correctly sized in relation to the aircraft application and the air intake 10. The objective is to ensure that there is a clearance distance d 203 between the air intake 10 and the path of any contamination from a contamination mass m 206 that is above a mass level determined that could be detrimental to the compressor 11 and fuel cell 12 system. FIG. 6 highlights that whether this clearance distance d 203 is positive and therefore safe for the system is proportional to the velocity V 205 of the free air flow, which will have a direct relationship to: the velocity of the aircraft, the attitude angle 204 of the free air flow in relation to the contamination deflector 16 and air intake 10, the contamination mass m 206, the suction inflow Q 207 into the air intake 10 and compressor 11, the air intake throat area A 208 and the gap distance D 209 between the contamination deflector 16 and the air intake 10. As can be seen in FIG. 6 it can be expected that there will be both an angling of the flow closer to the air intake 10 due to the attitude angle 204, but also neck down of the flow path towards the air intake 10 due to the suction inflow Q 207. The amount of neck down flow path deviation being proportional to a combination of the velocity V 205, the air intake area A 208 and the suction inflow Q 207.

[0080] The application of the proportionality relationship will need to consider a full range of suction inflow Q 207, which could include a ramp up to full power at low aircraft speed for instance during an aircraft go-around action. This may require the air intake throat area A 208 to be increased, and/or the width and height of the contamination deflector 16 to be increased to avoid contaminated air entering the air intake 10.

[0081] The attitude angle 204 of the free air flow should consider both transient and steady condition changes, a transient condition for example being a rapid pitch up or down of the aircraft, whereas the deployment of the aircraft's flaps causing an attitude change would represent a steady condition to be considered. The free air velocity V 205 would typically be the aircraft's velocity through the air, plus any local aerodynamic effects, and will normally be most challenging for the anti-contamination system and contamination deflector 16 sizing at low aircraft speed. The contamination mass m 206 target level should be set considering both the effect of an individual piece of contamination on the fuel cells 12, and multiple instances of the contamination mass m 206 occurring concurrently, in which case the effect of the density of the contamination should be accounted for in the target setting and in the sizing of the contamination deflector 16 and air intake 10.