Abstract:
An aircraft component assembly has a structural body and a thermal management de-icing system for minimizing or preventing ice build-up on leading edges of the body. The system includes a supply line for flowing heated fluid to the leading edges and a cooling device that interposes the supply line to prevent overheating of the leading edges thus protecting bodies that may be made of composite materials that are more susceptible to heat.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to an aircraft component assembly and more particularly to an aircraft component assembly having a thermal management de/anti-icing system. 
         [0002]    Aircraft components such as nacelles have leading edges that may have a tendency toward ice build-up during adverse weather conditions. This icebuild-up may increase the weight of components, increase aerodynamic drag and alter airflow surfaces which can cause performance degradation of (for example) the fan and/or engine in the nacelle region. To address this icing issue, aircraft components may have an anti-ice or de-icing systems. An anti-icing system is intended to heat the surface of the component to a high enough temperature that when water droplets impinge, they either evaporate or they do not freeze and run-off of the component surface. A de-icing system is intended to be activated when ice may or already has formed, and provides enough thermal energy to the surface of the component to detach the ice and allow it to fall off. (We will refer herein to both types of systems simply as “de-icing.”) Many current de-icing systems utilize hot engine bleed air as the heat source which is channeled to the aircraft component such as a nacelle inlet leading edge where it is used to prevent or melt ice formation. Because the bleed air is very hot (for example 700-1,000 degrees Fahrenheit), the nacelle inlet leading edges are typically made of a metal material so that their mechanical properties and performance do not degrade when heated to the temperature of the bleed air. 
         [0003]    With recent advancements in material technology, light-weight composite materials are being more readily used in nacelle manufacturing. Unfortunately, such composite materials are not capable of handling the elevated temperatures produced by typical de-icing systems using bleed air. Other thermal de-icing systems have been proposed which utilize electric resistive heating on the backside of the aircraft component to be de-iced instead of bleed air, where the temperature is better controlled by the thermal-electric system to permit the use of lightweight composite materials. But these types of systems have their own drawbacks, including cost and complexity. For this and other reasons, there is a need to improve de-icing systems to enable, for example, greater flexibility in the use of composite materials. 
       SUMMARY 
       [0004]    An aircraft component assembly according to one, non-limiting, embodiment of the present disclosure includes a structural body; and a thermal management system for the prevention of ice build-up on the structural body, the thermal management system having a first line for the flow of heated supply air and located upstream from and communicating with the structural body to heat it and prevent or remove ice build-up, and a cooling device interposed with the first line to reduce supply air temperature. 
         [0005]    Additionally to the foregoing embodiment, the structural body is made of a composite material. 
         [0006]    In the alternative or additionally thereto, in the foregoing embodiment, the composite material is epoxy based. 
         [0007]    In the alternative or additionally thereto, in the foregoing embodiment, the composite material is polyimide based. 
         [0008]    In the alternative or additionally thereto, in the foregoing embodiment, the heated supply air is compressed air from a compressor section of an engine. 
         [0009]    In the alternative or additionally thereto, in the foregoing embodiment, the cooling device includes a second line communicating with the first line for the flow of cooling air that mixes with the heated supply air. 
         [0010]    In the alternative or additionally thereto, in the foregoing embodiment, the cooling device is a heat sink that cools the heated supply air to a temperature safe for the structural body. 
         [0011]    In the alternative or additionally thereto, in the foregoing embodiment, the heatsink is an elongated portion of the first line in an area where heat will conduct out of the first line to cool the heated supply air temperature. 
         [0012]    In the alternative or additionally thereto, in the foregoing embodiment, the elongated portion is attached to a metallic plate that is exposed on one side to the ambient air flow. 
         [0013]    In the alternative or additionally thereto, in the foregoing embodiment, the assembly includes a Venturi tube joining the first and second lines. 
         [0014]    In the alternative or additionally thereto, in the foregoing embodiment, the composite material is bismaleimide based. 
         [0015]    In the alternative or additionally thereto, in the foregoing embodiment, the heated supply air is compressed air from a compressor section of an engine. 
         [0016]    In the alternative or additionally thereto, in the foregoing embodiment, the cooling device includes a control valve in the second line. 
         [0017]    In the alternative or additionally thereto, in the foregoing embodiment, the first line is interposed by a control valve. 
         [0018]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in-light of the following description and the accompanying drawings. It should be understood, however, the following description and figures are intended to be exemplary in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiments. The drawings that accompany the detailed description can be briefly described as follows: 
           [0020]      FIG. 1  is a schematic of an aircraft component assembly illustrated on a turbofan engine according to one, non-limiting, embodiment of the present disclosure; 
           [0021]      FIG. 2  is a perspective view of the aircraft component assembly on the turbofan engine with portions of a nacelle removed to show internal detail and a cooling device of the assembly including an air intake integrated into an external surface of a nacelle pylon for receiving external air to the aircraft as a cold source; 
           [0022]      FIG. 3  is a side view of the aircraft component assembly on a turbofan engine with portions of the nacelle removed to show internal detail and the cooling device of the assembly including an air intake or scoop for receiving turbine cooling air as the cold source; 
           [0023]      FIG. 4  is a schematic of a second embodiment of an aircraft component assembly illustrated on the turbofan engine, and having a heat sink as a cooling device; 
           [0024]      FIG. 5  is a partial perspective view of the second embodiment of the aircraft component assembly illustrated on the turbofan engine shown in phantom, and wherein the heat sink is a radiator; 
           [0025]      FIG. 6  is a cross section of the radiator taken along line  6 - 6  of  FIG. 5 ; 
           [0026]      FIG. 7  is a partial cross section of a third embodiment of a heat sink of an aircraft component assembly; and 
           [0027]      FIG. 8  is a schematic of a third embodiment of an aircraft component assembly illustrated on the turbofan engine. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Referring to  FIG. 1 , an aircraft component assembly  20  is illustrated having a structural body  22  and a thermal management de-icing system  23 . The structural body  22  may include a leading edge  24  that is susceptible to the build-up of ice during adverse weather conditions. The thermal management de-icing system  23  may further include a heat source  26  for producing a heating fluid  28  (that may be air as one, non-limiting, example), a supply line  30  in fluid communication between the heat source  26  and the leading edge  24 , and a cooling device  32  interposing the supply line  30  and capable of cooling the heating fluid  28 . It is contemplated and understood that the term ‘line’ may include any structure that defines a channel for flowing fluid. The aircraft component assembly  20  may be, as one example, a nacelle assembly. More specifically, the structural body  22  is illustrated as a nacelle inlet of a propulsion system; however, it is understood that the structural body  22  may be any body susceptible to ice build-up, and may also include, as non-limiting examples, a nacelle pylon, an aircraft wing, an aircraft tail, and a helicopter blade. 
         [0029]    The cooling device  32  may include a cold source  34  and a supplemental cooling line  36  that is in fluid communication between the cold source  34  and the supply line  30 . A cooling fluid  38  (that may be air as one example) flows from the cold source  34  and into the supply line  30  for limiting or controlling the fluid temperature at the leading edge  24 . If the heating and cooling fluids  28 ,  38  are air, the respective supply and cooling lines  30 ,  36  may be open-looped thus having a common outlet  40  that may be in fluid communication with external air about the aircraft. For further design simplicity, system robustness and minimal weight considerations, the heat source  26  may be non-electric and may further be bleed air extracted from an aircraft engine  42  and partially heated through kinetic energy of an upstream engine compressor as one, non-limiting example. For similar considerations and as one example, the cold source  34  may be an inlet of the cooling line  36  that accepts ambient air (e.g. air external to the engine and/or aircraft). 
         [0030]    The thermal management de-icing system  23  may further include a flow control or isolation valve  44  in the supply line  30  upstream of the cooling device  32 . Control of the valve  44  between open, intermediate, and closed positions may be controlled by a controller  46  that sends and receives electric signals  48  between the valve  44  and a temperature sensor  50  strategically located at the leading edge  24 . When icing is not a concern, the control valve  44  may be closed, and during icing conditions the valve  44  may be open. It is further contemplated and understood that other control valve orientations may be applied including pressure regulated systems, and systems including placement of a control valve in the supply line  30  downstream of the cooling device  32  and/or in the cooling line  36 , and may be dependent upon a wide variety of factors including ambient air temperature extremes, bleed air temperature, a need to conserve heated bleed air, engine operating conditions, positioning of sensor  50 , pressure, and other factors. 
         [0031]    The leading edge  24  of the structural body  22  may not be made of a metal material capable of handling elevated temperatures without incurring structural damage or other degradation. The entire structural body  22  or at least the leading edge  24  may be made of a light-weight composite material and controllably heated with the supplemented heating fluid  28  without incurring elevated temperature damage. Non-limiting examples of such composite materials include an epoxy based material, a bismaleimide (BMI) based material, and a polyimide (PI) based material. Use of the thermal management de-icing system  23  may facilitate a reduction in seams between parts. If the leading edge  24  is constructed of a composite material system, it may be advantageous to continue the leading edge aft and to the forward edge of the fan cowl as a single, unitary component. If the entire inlet is a single piece, then the number of seams and their associated steps and gaps are minimized, and less steps and gaps reduces aerodynamic drag. 
         [0032]    Referring to  FIG. 2 , the aircraft component assembly  20  may be part of a turbofan engine  52  constructed to rotate about an engine axis  54 . The engine  52  may have a nacelle  56  that supports and generally surrounds an upstream fan section  58  and a downstream engine core that may include a compressor section  60 , a combustor section  62  and a turbine section  64 . Generally, the fan section  58  supplies or drives air into both a bypass flowpath located radially outward from and surrounding the engine core and an inner engine core flowpath. The bypass air (see arrow  65  in  FIG. 3 ) flowing through the bypass flowpath may provide the majority of engine propulsion for the aircraft. The core-air flowing through the core flowpath may first be compressed/pressurized by the compressor section  60 , and then generally divided into supplemental air and combustion air. The pressurized supplemental air flows, and is therein distributed, through a network of flowpaths for cooling combustor walls of the combustor section  62  and then components of the turbine section  64  such as, for example, airfoils. 
         [0033]    The high pressure combustion air received from the compressor section  60 , enters the combustor section  62  and is mixed with fuel and burned producing energy. This heated/combusted air is then expanded through the turbine section  64  transferring the energy to the turbine section that, in-turn, drives at least two concentrically located shafts (not shown) that power the fan section  58  and compressor section  60 . 
         [0034]    More traditional turbofan engines may have a bypass airflow to core airflow ratio (i.e. bypass ratio) of about six (6:1). More recent high-bypass ratio engines, such as an elliptical geared turbofan engine may have greater bypass ratios and that may exceed ten (10:1). Aircraft and associated nacelles are being built lighter using current composite material technology. Engines, like the geared turbofan, others, and future engines are running hotter producing hotter bleed air for anti/de-icing operations. 
         [0035]    Compressed air from the compressor section  60  may be used as the hot bleed air for anti-icing operations. This bleed air when extracted at or downstream of the compressor section  60  may be anywhere between 700 to 1100 degrees Fahrenheit. Such temperatures exceed the design limitations of most typical composite material systems used on aircraft structures like nacelles. For example, epoxy based composites should not be exposed to temperatures exceeding about 250 degrees Fahrenheit and polyimide based composites should not be exposed to temperatures that exceed about 450 degrees Fahrenheit. Therefore, thermal management or cooling of this bleed air is necessary to cool this hotter bleed air and manage anti-icing operations of composite materials that are more susceptible to over-heating than more traditional metallic components. It is further contemplated and understood that bleed air greater than 1100 degrees Fahrenheit may be extracted from the engine where engine efficiency demands may dictate. As a consequence, the system  23  may also be beneficially applied in some cases to nacelles constructed of traditional metallic components. 
         [0036]    Referring to  FIGS. 1 and 2 , the structural body  22  of the aircraft component assembly  20  may further include a plenum  66  defined at least in-part by an interior surface of the leading edge  24 . The plenum  66  may be annular in shape. Line  30  of the thermal management de-icing system  23  may further include an outlet swirl nozzle  68  disposed in the plenum  66  and positioned to urge circular or circumferential flow in the plenum in a single direction (i.e. clockwise or counterclockwise direction about the engine axis  54 ). The heat source  26  may be hot bleed air controllably taken from the compressor section  60  of the turbofan engine  52 . It is further contemplated and understood that the hot bleed air may be taken at any point downstream of the compressor section  60  and may not be limited to the compressor air and/or pressurized supplemental air flow. 
         [0037]    The cold source  34  of the cooling device  32  may include an air inlet which could take the form of a scoop  70  carried by an exterior skin of a pylon  72  of the nacelle  56 , or alternatively the scoop  70  could be mounted on an external surface of the nacelle, or inside the fan bypass duct, or an inlet may be positioned anywhere where a source of cold air may be obtained. The cooling device  32  may further include a regulating or control valve  74  located in the line  36  for controlling the rate of cooling air  38  flow in line  36 . Lines  36  and  30  may join and integrate the hot and cold air flow with a Venturi tube  75  (see  FIG. 2 ) where the flow of bleed air is throttled through an orifice and a region of low pressure is created to pull in the cold air  38 . When the aircraft is on the ground and not in motion, de-icing can still be turned on and cooling air  38  may still flow through line  36  via the Venturi effect. Also, during flight the Venturi tube  75  may ensure that cooling air  38  is drawn into and mixed with the heating fluid  28 , instead of having the heating fluid  28  reverse flow through the cooling device  32  and escape out of the scoop  70 . Other Venturi arrangements may be applicable and known to those skilled in the art. 
         [0038]    The controller  46  may function to maintain a consistent flow rate, mass flow rate, or pressure, possibly at a prescribed temperature at or near the outlet nozzle  68 . This may be achieved through control of the control valve  74  of the cooling device  32  and the control valve  44  of the thermal management de-icing system  23 . As shown in  FIG. 3 , the valve  44  may include regulating or control valve  44   a  and an isolation valve  44   b  upstream of control valve  44   a.  Alternatively, valve  44  may include redundant valves  44   a,    44   b  solely for system robustness and safety precautions. Flow rate and temperature requirements of the de-icing air flow may be based on the temperature of ambient air around the nacelle inlet  22  and/or the inlet nose lip, and the rate at which air is traveling past the surface to provide cooling. Due to these factors, less heating air may be required in a ground based de-icing condition since the air would be at a higher temperature and at a slower flow rate. Both conditions would reduce the requirement for thermal energy to maintain the temperature of the nose lip at a point that would provide the de-icing capability. However, a sufficient flow rate should be maintained to ensure heating is not localized and the entire nose lip is at a sufficient temperature. 
         [0039]    Referring to  FIG. 3 , an alternative cold source  34  is illustrated, that may share the air scoop  70  with another (or pre-existing) cooling system  77  of the turbine section  64  such as, for example, an active clearance control cooling system. That is, the air scoop  70  takes a portion of the bypass air  65  from the fan section  58  as a cooling source for both the de-icing system  23  and the turbine system  77 . The air scoop  70  may be located at or near the turbine section  64  for receiving a portion of the bypass air  65 . The cooling device  32  extracts a portion (i.e. cooling air  38 ) of this bypass air portion for cooling the hot bleed air. 
         [0040]    Referring to  FIG. 4 , a second embodiment of an aircraft component assembly is illustrated wherein like elements to the first embodiment have the same element numbers except with the addition of a prime symbol. An aircraft component assembly  20 ′ has a cooling device  32 ′ that may be a passive heat sink. More specifically, the heat sink  32 ′ may be an elongation of a portion of the supply line  30 ′ to enable additional heat conduction through the walls of the line  30 ′ and into the surrounding ambient air. With application of the heat sink  32 ′, the line  30 ′ may include an outlet  40 ′ that only flows and/or expels heating fluid  28 ′ (i.e. no supplemental cooling air). The elongation of the supply line  30 ′ may be in the shape of a spiral that wraps around the air nacelle inlet, and may further transfer heat through the external skin of the nacelle inlet. Alternatively, the heat sink  32 ′ may include cooling fins, such as a radiator, to further enhance heat conduction. 
         [0041]    The heat sink  32 ′ may further include a base plate  84  as part of the external skin of the nacelle. Plate  84  may be a located at a pre-determined circumferential location in the nacelle or it may be ring shaped and circumferentially continuous. A portion of supply line  30 ′ may be attached to, or formed to, the plate  84  such that heat is transferred through the plate and into the surrounding environment (i.e. external to the nacelle). If the plate  84  is not circumferentially continuous, the elongation of the supply line  30 ′ may not be spiral in shape and may alternatively be sinuous where the line connects to the plate. The shape and configuration of the plate  84  and line  30 ′ are determined by the needed heat transfer that is dependent upon the temperature limitations internal to the nacelle (e.g. the nacelle cavity containing the supply line  30 ′) and the surrounding ambient air temperature(s). 
         [0042]    Referring to  FIGS. 5 and 6 , the heat sink  32 ′ is illustrated as a radiator located substantially inside a nacelle inlet of a nacelle  56 ′ as the structural body  22 ′. The nacelle inlet  22 ′ may have inner and outer walls  76 ,  78  spaced radially from one-another, concentric to the engine axis  54 ′, and defining an annular chamber  80 , there-between. The radiator  32 ′ may be in the chamber  80  and may include a plurality of thermally conductive fins  82  with the line  30 ′ running multiple passes through each fin. Each fin  82  may be rigidly secured to a base plate  84  for structural support. The fins  82  transfer heat from line  30 ′ and into chamber  80  through convection, and may also transfer heat into the base plate  84  through conduction. The base plate  84  may be mounted to the outer wall  78  of the nacelle inlet  22 ′, and may be metallic or made of a thermally conductive material for transferring heat from the fins  82  and to the surrounding ambient air of the aircraft similar to the heat sink best shown in  FIG. 4 . 
         [0043]    The adjacent outer wall  78  may be made of a composite material that is generally not thermally conductive and/or heat resistant. Therefore, the base plate  84  may be an integral part of the outer wall  78  sharing a common and/or contiguous external surface  86 . As high velocity ambient air passes the plate  84 , efficient heat convection occurs from the plate  84  to the ambient air surrounding the aircraft. It is further contemplated and understood that another, non-limiting, example may include the nacelle inlet  22 ′ being entirely made of a composite material with the base plate  84  being secured inside the nacelle inlet  22 ′ (not shown). In such instances, the radiator  32 ′ may reduce anti/de-icing air temperature in the line  30 ′ substantially through heat convection from the fins  82  and to the ambient air in the annular chamber  80 . 
         [0044]    Referring to  FIG. 7 , a third embodiment of an aircraft component assembly is illustrated wherein like elements to the second embodiment have the same element numbers except with, the addition of a double prime symbol. A heat sink  32 ″ may transfer heat primarily through a base plate  84 ″ attached directly to an elongated, sinuous, or spiral portion of a supply line  30 ″, and into the surrounding ambient air external of the nacelle. This primary direction of heat transfer to the surrounding ambient air environment, as oppose to heat transfer into an annular chamber  80 ″ is advantageous when temperatures within the chamber are projected to be too high to achieve desired heat transfer. The line  30 ″ may further include cooling fins  82 ″ that are internal to the line, co-extend longitudinally with the line, and spaced circumferentially apart from one-another. 
         [0045]    Referring to  FIG. 8 , a fourth embodiment of an aircraft component assembly is illustrated wherein like elements to the first embodiment have the same element numbers except with the addition of a triple prime symbol. An aircraft component assembly  20 ′″ has a thermal management de-icing system  23 ′″ that may have a supply line  30 ′″ that is generally closed-loop and includes a supply leg  88  for flowing fluid from a heat source  26 ′″ to a leading edge  24 ′″ of a structure body  22 ′″, and a return leg  90  for returning flow back to the heat source  26 ′″. The heat source  26 ′″ (as one, non-limiting, example) may include a heat exchanger  92  and a heat generating portion  94  of an operating engine  52 ′″. One, non-limiting example of a heat generating portion  94  may be an elliptical gear box of a geared turbofan engine  52 ′″. The heat exchanger  92  may surround the gearbox housing and thus extract heat. As another example, the heat exchanger  92  may be immersed in an oil reservoir (not shown) of the gearbox and thus function to advantageously cool the gearbox oil while extracting the necessary heat for de-icing operations. Flow through the supply line  30 ′″ may be created by a pump (not shown) that is part of the elliptical gear box and/or part of a cooling system for the gearbox known in the art. A cooling device  32 ′″ of the de-icing system  23 ′″ may be associated with at-least the supply line  30 ′″ for cooling the heating fluid. De-icing system  23 ′″ may be advantageous where use of engine cooling air as a heated bleed air source is not desirable due to engine operating efficiency demands and/or advantageous where internal engine components are in need of a cooling means. 
         [0046]    It is understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude and should not be considered otherwise limiting. It is also understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will also benefit. Although particular step sequences may be shown, described, and claimed, it is understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0047]    The foregoing description is exemplary rather than defined by the limitations described. Various non-limiting embodiments are disclosed; however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For this reason, the appended claims should be studied to determine true scope and content.