Abstract:
An aircraft includes a fuselage and wings mounted on opposite sides of the fuselage for sustained forward flight. An engine is mounted in the fuselage or at least one of the wings and includes an air intake. At least a portion of the air intake generally faces the forward direction for receiving intake air during forward flight. A filter assembly is mounted adjacent the air intake and disposed to impinge air and block objects from passing therethrough. A heated screen includes a heater and is mounted adjacent the air intake and upstream of the engine such that ice entering the air intake contacts the heated screen before entering the engine. A power source is provided to supply power to the heater.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 61/581,784, filed Dec. 30, 2011, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD 
     The field of this disclosure relates generally to air intake systems for aircraft and related methods, and more particularly, to heated screens and anti-icing systems for aircraft engine air intakes. 
     BACKGROUND 
     This section is intended to introduce various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion should be helpful in providing background information to facilitate a better understanding of the various aspects of the present invention. These statements are to be read in this light, and not as admissions of prior art. 
     An engine for aircraft propulsion requires intake air that is free from contaminants to provide for efficient combustion and avoid damage to internal engine components. Some known compressors and turbines are designed with small clearances between moving parts that maximize efficiency, but which also increase vulnerability to damage of engine parts from small foreign particles. Contamination of intake air, even in a small amount, may cause premature wear on engine components, increases maintenance costs, and degrades operational performance and reliability. Aircraft are exposed to contaminants when operating at low altitudes where air is frequently contaminated with material from the ground, such as sand and dust. This problem may be worse for helicopters and for tiltrotor aircraft due to rotor downwash and prolonged low-altitude operation. This problem may also be worse for fixed wing aircraft operating from unimproved airfields. Aircraft, including tiltrotor aircraft, also have a higher operating altitude than conventional helicopters and are thereby more frequently exposed to icing conditions in flight. Such conditions can cause ice to form in and around the engine intake, and this ice may damage the engine if allowed to enter the engine. A better system for preventing ice and contaminants from entering the engine is needed. 
     SUMMARY 
     In one aspect, an aircraft includes a fuselage and wings mounted on opposite sides of the fuselage for sustained forward flight. An engine is mounted in the fuselage or at least one of the wings and includes an air intake. At least a portion of the air intake generally faces the forward direction for receiving intake air during forward flight. A filter assembly is mounted adjacent the air intake and disposed to impinge air and block objects from passing therethrough. A heated screen includes a heater embedded therein and is mounted adjacent the air intake and upstream of the engine such that ice entering the air intake contacts the heated screen before entering the engine. A power source is provided to supply power to the heater. 
     In another aspect, a filter and anti-icing system for an air intake of an aircraft engine includes a filter assembly disposed to impinge air and block objects from passing therethrough. A heated screen is mounted adjacent the filter such that ice contacts the screen before entering the engine. The heated screen includes a heat conducting plate embedded therein. A power source is provided to supply power to the heater. 
     Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings are not to scale and certain features may be exaggerated for ease of illustration. 
         FIG. 1  is a perspective view of an aircraft (V-22) according to one embodiment of the present disclosure. 
         FIG. 2  is a perspective view of an engine of the aircraft of  FIG. 1 . 
         FIG. 3  is a cross-section of an engine intake area of the engine of  FIG. 2 . 
         FIG. 4  is an enlarged view of a portion of  FIG. 3 . 
         FIG. 5  is a front view of another aircraft (C-130) according to another embodiment. 
         FIG. 6  is a front view of still another aircraft (C-17) according to another embodiment. 
         FIG. 7  is a front view of yet another aircraft according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an embodiment of an aircraft  100 , and in this embodiment, the aircraft is a tiltrotor aircraft, such as a V-22 Osprey, though other aircraft or helicopters may use the systems of the present disclosure. For example, other aircraft may include those similar to a C-130 (aircraft  200  in  FIG. 5 ), or a C-17 (aircraft  300  in  FIG. 6 ), or a tri-jet (aircraft  400  in  FIG. 7 ). Other engine configurations, including single engine aircraft and aircraft with nose-mounted engines, are contemplated within the present disclosure. Note that embodiments of this disclosure may be advantageous for nose-mounted engines due to the proximity of the intake to the ground. 
     Aircraft  100  in  FIG. 1  generally includes a fuselage  102 , wings  103 , rotor blades  104 , and an aircraft engine  106  mounted in a nacelle  107 . The tiltrotor aircraft is configured such that the rotation axis of each rotor blade is independently and sequentially tiltable between a generally vertical position for generally vertical flight and a generally horizontal position for forward flight. The engine may be, for example, a turbine engine, a piston engine, or another type of engine suitable for causing rotation of rotor blades  104  and thereby providing thrust for the aircraft  100 . The fuselage  102  defines a forward direction  108 , as designated in  FIG. 1 . Each aircraft engine  106  includes an intake  110  for receiving air through a main opening  111  of the nacelle  107  for receiving air flow for use by the aircraft engine in a combustion process. It should be appreciated that other embodiments may include a different number of intakes for receiving intake air usable in a combustion process. In this embodiment, intake  110  is shown facing generally upward for hovering or vertical takeoff. Once in flight, the engine and rotor are capable of tilting forward so that the main axis of the engine is parallel to the forward direction  108  for forward movement or flight of aircraft  100 . In forward flight, intake air flows into the main opening  111  ( FIGS. 2-3 ) and then into the intake  110 . 
     As illustrated in  FIG. 3 , each nacelle of the aircraft  100  includes filter system  112  (one filter system for each intake) including filter media  124 . It should be appreciated that other embodiments may include a different number of filter assemblies. Prior filter systems for aircraft include those shown in co-assigned U.S. Pat. Nos. 6,595,742; 6,824,582; 7,192,462; 7,491,253; and 7,575,014, all of which are incorporated herein by reference. 
     An exemplary filter system  112  is illustrated in  FIGS. 2-4 . Each of the filter systems  112  is adjacent a respective one of the intakes  110 . Intake air passes through the filter system  112  prior to entering the air intake  110  of aircraft engine  106 . In other words, the filter system  112  is disposed to impinge air and block objects from entering the intake  110 . The filter system  112  is structured to filter intake air to remove containments therefrom, prior to permitting the intake air to enter the air intake  110  of the aircraft engine  106 . 
     Filter system  112  extends around the nacelle  107  forward of the engine inlet. The filter assembly  114  generally defines a substantially annular cross-section. More particularly, in this example embodiment, the filter system  112  defines a cylindrical filter assembly, as shown in  FIG. 3 . In this embodiment, the filter assembly is substantially conformal to the contour of the nacelle outer surface  125  to reduce or eliminate potential drag on the aircraft caused by the filter system, and thereby minimize or eliminate any “performance penalty” caused by the system. 
     The filter system  112  includes filter media  124  disposed at least partially about a circumference of the filter assembly  114  for removing contaminants from intake air entering the interior through the filter media  124 . A variety of configurations (e.g., size, shape, number of elements, orientation, etc.) of filter media  124  may be included in filter system embodiments. In this embodiment, filter media may include two or more filter elements. The filter elements are configured to remove particles from the intake air, as described in the patents referenced above, including sand, dust, or other particles which may be prevalent in various operating environments for aircraft  100 . 
     A suitable bypass of this embodiment includes a door or valve  126  disposed generally forward of the filter assembly  114  and intake  110 . In this embodiment, the valve is a butterfly valve pivotable about a pivot pin  127  mounted laterally or transverse to the flow of air into the nacelle  107  and into the intake  110 . An actuator (not shown) is operable to move or pivot the valve from a closed position for directing air through the filter assembly, to an open position for allowing unfiltered air to enter the intake  110  directly, without filtering the air. When closed and the engine is operating, the bypass inhibits unfiltered air from entering the engine, e.g., when the aircraft is hovering, or when the aircraft is near the ground. The bypass may be such that it substantially seals out air and thereby prevents unfiltered air from entering the engine. It is also contemplated that the bypass may have partially opened/closed positions to allow some unfiltered air into the intake  110 . 
     Referring to  FIGS. 3 and 4 , a de-icing or anti-icing system includes a heated screen  130  for reducing or eliminating ice in the engine intake area (e.g., when the engine is in operation). The screen  130  is mounted in the nacelle  107  of the aircraft  100 . The heated screen  130  includes a plate  132  with holes  134  therethrough and a heater  136  (e.g., a heating element, a heat conducting plate or conductive element). In this embodiment, the plate  132  is made of a composite material. More particularly, the plate  132  includes a composite matrix, which may include carbon fiber. The plate  132  may suitably be made using a resin transfer molding (RTM) process with interlaying or interwoven heating elements, or made of an interlayered RTM. Alternatively, the plate  132  may include a heated metal plate or metal screen. The heater  136  may suitably be embedded between adjacent layers of composite material. As shown, the heater  136  is disposed about midway through the composite matrix, and extends substantially the entire length of the plate. The heater  136  is electrically connected to a power source for powering the heater, and may be connected to a controller as described below. 
     As shown, the screen  130  is positioned in the nacelle  107  between an inner edge  138  of the nacelle and the intake  110 . The screen of this embodiment is positioned adjacent the filter assembly  114 . In this embodiment, the screen  130  is positioned in the nacelle such that water or ice entering the nacelle must contact the screen before entering the engine when the bypass  126  is closed. The screen  130  is generally annular and in this embodiment is disposed to have an angle, e.g., a diverging angle, from the inner edge  138  of the nacelle to the intake  110 . 
     In this embodiment, holes  134  are formed through the plate  132  to allow air or water to flow from an upper surface of the plate to a lower surface. In this way, water can flow from the plate. Because it is water, rather than ice, it will not damage the engine if it passes through to the engine. 
     The heated screen  130  of this embodiment includes limited or no fasteners. Among other advantages, the risk of a loose or broken fastener entering the engine intake and damaging the engine is reduced due to the absence of fasteners. 
     In some embodiments, a sensor (not shown) on or adjacent the screen detects ice on the screen and/or may detect conditions under which ice is likely to form. For example, the sensor is operable to detect at least one of temperature of the screen or formation of ice on the screen. The aircraft  100  includes a controller (not shown) to control one or more functions of aircraft  100 . The controller may include or be integrated into, for example, an air vehicle computer or controller. The heating element is connected to the controller so that the controller is operable to energize the heating element to inhibit formation of ice on the replacement filter system  112 . In this exemplary embodiment, the heated screen and the sensor thereon are connected to and responsive to the controller  136 . More specifically, in one example, when the sensor signals the controller that there is ice on the screen, the controller activates the heater to thereby melt the ice on the screen or to prevent ice from forming. Note that in other embodiments, a sensor disposed on the aircraft remote from the screen may signal the controller that the aircraft is in icing conditions, and this signal may cause the controller to activate the heater in the screen to avoid ice formation or build-up. 
     The heater  136  may include multiple sections that may be powered or activated separately and independently of one another. For example, certain or discrete sections of the heater  136  may be activated, while other sections remain de-activated to conserve power. A controller may be included that selects which sections to activate depending on the conditions. The icing conditions may be indicated to the controller by the above-described sensor or other sensors. 
     In use, intake air may enter the interior through the forward opening or through the filter. Water may enter the inside of the nacelle  107 , e.g., through the main opening and collect on the screen  130 . This water that enters the nacelle  107  tends to collect on the screen. When the aircraft is flying in icing conditions, the water may freeze on surfaces of the nacelle  107 , including the screen  130 , and form ice. Or, ice may enter the nacelle through the opening and settle on the screen. In either situation, the heater  136  is activated, either by the controller or by the aircraft operator, to cause melting of any ice formed on the screen. 
     When introducing elements of the present invention or the embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.