GB2482480A

GB2482480A - An electrostatic particle ingress inhibitor

Info

Publication number: GB2482480A
Application number: GB1012956.7A
Authority: GB
Inventors: Peter G Lloyd
Original assignee: Lockheed Martin UK Insys Ltd
Current assignee: Lockheed Martin UK Ampthill Ltd
Priority date: 2010-08-02
Filing date: 2010-08-02
Publication date: 2012-02-08
Also published as: GB201012956D0

Abstract

The present invention relates to a system and method for inhibiting the ingress of particles into the compressor 14 of a turbofan jet engine 10. The system comprises a deflection electrode 24 arranged to electrostatically deflect the particles through an air bypass 20 of the engine. A charge electrode 22 may be arranged to electrically charge the particles. The charge electrode may be arranged to generate an electrostatic field proximal to an air intake of the engine. The charge electrode may be formed of one or more members arranged to extend across an air intake of the engine and may be fenestrated and/or be a grill or grid. The deflection electrode may be configured to be arranged between the internal periphery of the air intake and the hub of the jet engine. A sensor may be provided which is operable to detect an amount of airborne particles and the electric charge of the airborne particles

Description

System and Method

Field

The present invention relates to a system and method for inhibiting the ingress of particles into the compressor of a jet engine.

Background

Particles emitted into the air can interfere with the jet engines on aircraft. For example, fine ash and dust emitted in to the atmosphere following volcanic eruption can have catastrophic effects on normal engine operation leading to loss of power in, or complete failure of, the engine. Similar problems exist for jet engine aircraft and helicopters operating in dusty terrain such as desert regions.

Volcanic ash consists of small tephra or particles typically less than 2 millimeters in diameter. Such particles generally comprise fragments of pulverized rock and glass created by volcanic eruptions. Due to the highly energetic nature of their creation, the particles may be ionized. Furthermore, once emitted into the Earths atmosphere the particles may become ionized by UV radiation from the Sun.

However, it is also possible that the particles are neutrally charged.

The effect of such particles on jet engines can be particularly severe as large volumes of air are sucked into the engine during combustion operation. This poses a particular danger to aircraft flying through or near regions with high airborne particulate concentrations.

On turbofan engines, air intakes typically include fans and such fans can result in a modular mix of different types of airborne particles in the engine. Combustion chambers of jet engines typically operate at temperatures of approximately 1400 °C. Very fine volcanic ash particles, for example, sucked into jet engines typically melt at temperatures of approximately 1100 °C. When the particles melt

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they can fuse onto engine turbine blades and other parts of the engine. The effect of volcanic ash on the operation of a jet engine can lead to an effect known as combustion power failure, which can be characterised by one or more of the following effects.

Volcanic ash particles can erode and destroy parts of the jet engine. Rotating parts can thus become out-of-balance or dislodged and can cause jams in the rotating machinery. Also a simple lack of oxygen in the combustion chamber can cause the engine to lose power or fail completely.

Further problems can also include incorrect readings in the engine temperature sensors, compressor stall and flameout.

To prevent the ingress of airborne particles the only known solution is to avoid flight paths where the particles may be present. This involves changing the flight path of an aircraft by decreasing or increasing altitude, and/or changing course.

However, a change in course or altitude may not be possible due to geographical restrictions such as mountains or no-fly zones. Furthermore, changing course can increase fuel expenditure and a typical aircraft may not have enough fuel to complete a particular journey. Further still, flights may be grounded as a result of such particles.

Aspects and embodiments of the invention were devised with the foregoing in mind.

Summary

In accordance with a first aspect of the invention there is provided a system for inhibiting the ingress of particles into the compressor of a jet engine, the system comprising; a deflection electrode arranged to electrostatically deflect the particles to an air bypass of the jet engine.

In accordance with a second aspect of the invention there is provided a turbofan jet engine in combination with the system of the first aspect.

In accordance with a third aspect of the invention there is provided an aircraft comprising the turbofan jet engine according to the second aspect.

One or more embodiments of the invention provide a system which allows engines to operate in environments where there is a high concentration of particles. One or more embodiments of the invention provide a system which allows aircraft to fly through airspace where there is a high concentration of particles.

One or more embodiments of the invention comprise a sensor to sense the presence of particles and/or the electrical charge of the airborne particles.

In one or more embodiments the electrodes are arranged to be operated by the sensor. In one or more embodiments the polarity of the electrodes is controlled by the sensor.

One or more embodiments of the invention of the invention provide a system that can be retro-fittable to a jet engine of an aircraft.

Specific embodiments in accordance with embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-sectional elevation of a jet engine comprising the system of the present invention; Figure 2a is an end view of the air intake side of a turbofan engine comprising the system of the present invention; and Figure 2b is a cross-sectional elevation showing a central hub region of the jet engine.

Referring to Figure 1, a typical jet engine 10, such as for example a Rolls Royce Trent Series engine, comprises an air intake fan 12, a compressor 14, a combustion chamber 16, an exhaust 18 and an air bypass 20. When the engine is in use air enters the intake of the engine in the direction shown by arrows A. A proportion of intake air will be directed into the compressor 14 which compresses the air for combustion in the combustion chamber 16. The remaining proportion of this air will be directed into the air bypass 20 whereby it will simply bypass the compressor 10 and the combustion chamber 16, taking no part in the combustion process and exit the engine through the exhaust 18.

In accordance with embodiments of the invention a first electrode 22 can be arranged such that it substantially covers the air intake of the engine 10. The first electrode 22 is preferably fenestrated (see Figure 2) such that it does not restrict the aerodynamic performance of the engine 10 and so that air comprising particles is free to pass into the engine 10. The fenestrated first electrode 10 can be formed of a grid or grill of electrode material where the fenestrations are typically in the order of tens of millimetres. Optionally, the first electrode may typically be formed of a series of spoke like members extending outwardly from a hub 26 located at the centre of the electrode. The hub 26 may substantially coincide with a central axis of the engine 10.

In the case of a turbo jet engine the full diameter of the engine is used for air intake. Therefore, as shown in Figure 1, a second electrode 24 may be arranged around the internal periphery of the air intake of the engine 10 so that all, or a substantial proportion of the particles can be deflected, Air intakes to turbofan engines are usually only one third of the diameter of the air intake fan 12. Therefore alternatively, and as shown in Figure 2a, the second electrode 24 may be located at position between the casing 11 of the engine 10 and the hub 26. For example, the second electrode 24 may be located at approximately two thirds of the radius of the engine intake.

As mentioned above, the first electrode 22 can be formed of a grill or grid of electrode material. The individual elements forming the grill or grid can be hollow.

In addition the second electrode 24 can be hollow. Using hollow electrodes reduces the weight of the electrode materials. Optionally, the second electrode 24 may be cylindrical.

The first 22 and second 24 electrode materials are entirely at the choice of the skilled person. For example, the material could be carbon fibre or other appropriate lightweight material coated with an appropriate metal.

The first electrode 22 is arranged to electrostatically charge the particles contained in the air as they enter the engine intake and pass the first electrode 22. The second electrode 24 is arranged to deflect the electrostatically charged particles away from the intake of the compressor 14. In this way the electrostatically charged particles will thereby be attracted towards the second electrode and deflected into the air bypass 20 of the engine 10.

The first electrode 22 will have an opposite polarity to the second electrode 24.

For example, the first electrode 22 may be a positive electrode (or anode) and the second electrode 24 will be a negative electrode (or cathode). The potential difference across the first and second electrodes will be in the region of hundreds of Kilovolts (kV). The potential difference should be such that the electrostatic force generated by the electrodes will be sufficient to deflect the charged particles when the engine is operating at maximum performance. )

By way of a non-limiting example, the electrical potential may be generated by any appropriate generator 30 as shown in more detail in Figure 2b. The electrical potential may be generated using an inductive generator placed at the spinning hub 26 of the air intake fan. Alternatively, the spinning hub 26 of the engine 10 could be used to turn a generator, such as a dynamo arrangement, either by direct contact or by rotating some permanent magnets (not shown) that are attached to a generator but are not actually in contact with the hub 26 itself.

Optionally, electrical power may be taken from the engines electrical power system.

In one or more embodiments, the electrodes may be operated by one or more sensors 28. By way of non-limiting example the sensors 28 can be laser scatteronieters that detect the ash and dust by means of the laser light reflected by the particles back into a light detector. Sensors 28 can be used determine the concentration of particulate material in the air. lf the concentration of the particulate material exceeds a certain threshold then the sensors 28 will operate the electrodes. The sensors 28 may be located at the hub 26, or may be placed at any appropriate position on the engine or the structure of the aircraft.

In addition the sensors 28 may also have the ability to detect any charge present on the particles. If the majority particles have a neutral charge for example, then the polarity of the electrodes can be set appropriately, such that the particles are charged by the first electrode 22, and deflected by the second electrode 24.

Detecting the charge of the particles, particularly where the majority of particles in the air are either one of negatively charged or positively charged allows the system to be adapted to deflect the either negatively or positively charged particles as the need arises. For example, if the majority of the particles are negativity charged then polarity of the first electrode 22 can be set to negative, and the second electrode 24 can be set to positive.

However, in flight, particles of opposite charge to the above example, that is positive, may be encountered. In this case the polarity of the electrodes can be reversed such the first electrode 22 is positive and the second electrode 24 is negative.

ln this way embodiments of the present invention can adapt to changes in the polarity of particles which may be encountered in-flight.

In addition, information from the sensors 28 may be made available to the instrument panel in a cockpit of the aircraft using appropriate indicator means.

The indicators will inform the pilot that high densities of particulate matter have been encountered.

The electrodes and generator 30 may be fitted to the engine by any appropriate mechanical supports and/or securing means such that the system can be retrofitted to an engine. The mechanical supports 13 may be non-conducting.

As used herein any reference to "one embodiment" or "an embodiment" means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

In addition, use of the "a" or "an" are employed to describe elements and components of the invention. This is done merely for convenience and to give a general sense of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention. For example, the electrodes may be made of any appropriate material, such as Noble metals which are resistant to corrosion and oxidation. The sensors can be any appropriate type such as scatterometers, or radiation detectors. The system and method may also be used in land or sea based vehicles which rely on jet engines for their motive power, for example the Chrysler Defense Ml Abrams Tank.

The scope of the present disclosure includes any novel feature or combination of features disclosed therein either explicitly or implicitly or any generalisation thereof irrespective of whether or not it relates to the claimed invention or mitigate against any or all of the problems addressed by the present invention.

The applicant hereby gives notice that new claims may be formulated to such features during prosecution of this application or of any such further application derived therefrom. In particular, with reference to the appended claims, features from dependent claims may be combined with those of the independent claims and features from respective independent claims may be combined in any appropriate manner and not merely in specific combinations enumerated in the claims.

Claims

Claims 1. A system for inhibiting the ingress of particles into the compressor of a turbofan jet engine, the system comprising; a deflection electrode arranged to electrostatically deflect the particles through an air bypass of the jet engine.
2. The system of claim 1, further comprising a charge electrode arranged to electrically charge the particles.
3. The system of claims 1 or 2, wherein the charge electrode is arranged to generate an electrostatic field proximal to an air intake of the jet engine.
4. The system of claims 1 to 3, wherein the charge electrode is formed of one or more members arranged to extend across an air intake of the jet engine.
5. The system of claims 1 to 4, wherein the charge electrode is fenestrated and/or is a grill or grid.
6. The system of claim 1, wherein the deflection electrode is configured to be arranged around the circumference of the internal periphery of the air intake of the jet engine.
7. The system of claim 1, wherein the deflection electrode is configured to be arranged between the internal periphery of the air intake and hub of the jet engine.
8. The system of claims I to 5, wherein the charge electrode is configured to be arranged substantially coaxially with the deflection electrode.
9. The system of claims I to 8, wherein in use the charge electrode is at different electrical polarity to the deflection electrode.
10. The system of claims 1 to 9, wherein an electrical potential across the electrodes is of the order of 100 kV.
11. The system of claim 10, wherein the electrical potential is generated by an electrical generator,
12. The system of claim 11, wherein the electrical generator is an inductive generator.
13. The system of any one or more of the preceding claims, further comprising a sensor, wherein the sensor is operative to detect an amount of airborne particles and the electrical charge of the airborne particles.
14. The system of claim 13, wherein the electrodes are arranged to be operated by the sensor.
15. The system of claim 14, wherein the polarity of the electrodes is controlled by the sensor.
16. A turbofan jet engine, in combination with the system as set out in one or more of the preceding claims.
17. An aircraft comprising the turbofan jet engine of claim 16.
18. A method of inhibiting the ingress of particles into the compressor of a jet engine, the method comprising: electrostatically deflecting particles to an air bypass of the jet engine.
19. The method of claim 17, further comprising electrically charging the particles.
20. The method of claims 17 or 18, further comprising generating an electrostaticfield proximal to an air intake of the jet engine.
21. A system, turbofan engine or aircraft substantially as hereinbefore described for respective embodiments and with reference to respective Figures.* 22. A method substantially as hereinbefore described for respective embodiments and with reference to respective Figures.Amendments to the claims have been filed as follows: 1. A system for inhibiting the ingress of particles into the compressor of a turbofan jet engine, the system comprising; a deflection electrode arranged to electrostatically deflect the particles through an air bypass of the jet engine.2. The system of claim 1, further comprising a charge electrode arranged to electrically charge the particles.3. The system of claims 1 or 2, wherein the charge electrode is arranged to generate an electrostatic field proximal to an air intake of the jet engine.4. The system of claims 1 to 3, wherein the charge electrode is formed of one or S.,...* more members arranged to extend across an air intake of the jet engine.S..... * S5. The system of claims 1 to 4, wherein the charge electrode is fenestrated and/or is a grill or grid.6. The system of claim 1, wherein the deflection electrode is configured to be arranged around a circumference of the internal periphery of an air intake of the jet engine.7. The system of claim 1, wherein the deflection electrode is configured to be arranged between the internal periphery of the air intake and a hub of the jet engine.8. The system of claims I to 5, wherein the charge electrode is configured to be arranged substantially coaxially with the deflection electrode.9. The system of claims 1 to 8, wherein in use the charge electrode is at different electrical polarity to the deflection electrode.10. The system of claims I to 9, wherein an electrical potential across the electrodes is of the order of 100 kV.11. The system of claim 10, wherein the electrical potential is generated by an electrical generator, 12. The system of claim 11, wherein the electrical generator is an inductive generator.13. The system of any one or more of the preceding c'aims, further comprising a sensor, wherein the sensor is operative to detect an amount of airborne particles * and the electrical charge of the airborne particles.* .***. * *14. The system of claim 13, wherein the electrodes are arranged to be operated by the sensor. I 15. The system of claim 14, wherein the polarity of the electrodes is controlled by thesensor.U16. A turbofan jet engine, in combination with the system as set out in one or more of the preceding claims.17. An aircraft comprising the turbofan jet engine of claim 16.18. A method of inhibiting the ingress of particles into the compressor of a jet engine, the method comprising: electrostatically deflecting particles to an air bypass of the jet engine.19. The method of claim 17, further comprising electrically charging the particles.20. The method of claims 17 or 18, further comprising generating an electrostaticfield proximal to an air intake of the jet engine.21. A system, turbofan engine or aircraft substantially as hereinbefore described for respective embodiments and with reference to respective Figures.
22. A method substantially as hereinbefore described for respective embodiments and with reference to respective Figures.SS..... * .SS..... * II..... * I S. ** * S * III....