Patent Publication Number: US-2021180514-A1

Title: Jet engine air inlet arrangement and method for manufacture thereof

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to jet engines; more specifically, the present disclosure relates jet engine air inlet arrangements that peripherally surround air inlets of jet engines. Moreover, the present disclosure relates to methods for (namely, method of) manufacturing jet engine air inlet arrangements. 
     BACKGROUND 
     Contemporary jet engines include de-icing systems. Ice formation on leading edges or surfaces of a given aircraft occurs when the given aircraft is flying at a high altitude, for example at an altitude of about 10 km or above, particularly when water droplets or ice particles at sub-zero temperature contact the leading edges or surfaces. Thus, ice formation may occur even below an altitude of about 10 km if there are conditions containing sub-zero temperatures and water droplet in the ambient air paired with sub-zero temperatures of aircraft or engine surfaces. 
     To perform a de-icing function, a given contemporary jet engines utilizes a de-icing arrangement, that forms a part of a jet engine air inlet arrangement that peripherally surrounds an air inlet of the given jet engine. The jet engine air inlet arrangement comprises an annular casing arrangement (such as a nose cowl) and a forward bulkhead. Furthermore, the anti-icing system primarily includes a tube arrangement for providing a flow of hot air, which enables the leading edges or surfaces to be de-iced. The tube arrangement is enclosed by the annular casing arrangement and supported on the forward bulkhead. Conventional jet engine air inlet arrangements suffer from various problem; for example, conventional jet engine inlet arrangements are too heavy that affects a functional efficiency of the given jet engine. Efficient de-icing of the annular casing arrangement is another problem, in which heat energy from the tube arrangement is expected to reach all nooks and corners of the annular casing arrangement to provide efficient de-icing. 
     Therefore, to ameliorate the technical problems encountered with known jet engine air inlet arrangements, there exists a need to provide an improved jet engine air inlet arrangement that is more effective when in operation and weighs less. 
     SUMMARY 
     The present disclosure seeks to provide an improved jet engine air inlet arrangement. The present disclosure also seeks to provide an improved method for manufacturing a jet engine air inlet arrangement. The present disclosure seeks to provide a solution to the existing problem of a weight of a jet engine air inlet arrangement being too big, and to the existing problem of inefficient de-icing provided by a conventional jet engine air inlet arrangement when in operation. An aim of the present disclosure is to provide a solution that overcomes, at least partially, the aforementioned problems encountered in prior art, and to provide a jet engine air inlet arrangement which is of lower weight, more efficient in de-icing and provides a higher structural rigidity. 
     In one aspect, the present disclosure provides a jet engine air inlet arrangement that peripherally surrounds an air inlet of a jet engine, wherein:
         the jet engine air inlet arrangement includes a front annular casing arrangement and a heating pipe arrangement disposed within a cavity provided within the front annular casing arrangement,   the heating pipe arrangement provides heating to the jet engine air inlet arrangement when in use,   the heating pipe arrangement is supported onto an annular internal bulkhead, wherein the annular internal bulkhead provides a back wall to the cavity;   the annular internal bulkhead is fabricated from deformed metal sheet, and includes a plurality of radially disposed stiffening projections and recesses in the back wall, and   the annular internal bulkhead includes inner and outer circumferential flanges that engage onto inside surfaces of the front annular casing arrangement behind the back wall, wherein a plurality of radially disposed stiffening projections and recesses result in the flanges being disposed at a distance of more than 60 mm behind the plurality of radially disposed stiffening projections and recesses.       

     The fabrication from deformed metal sheet may comprise at least one chosen from a deep drawn method or a super-plastic forming method. Alternatively, the annular internal bulkhead may be fabricated using a 3D printing method. Embodiments comprise fabricating the metal sheet from steel, Aluminium, Aluminium alloy, Titanium or a Titanium alloy. 
     Optionally, the front annular casing arrangement is provided with a plurality of perforations in fluid communication with the cavity, wherein the perforations provide, when in use, at least one of: heating of an external surface of the front annular casing arrangement leading into the air inlet of the jet engine, engine noise reduction. 
     Optionally, the annular internal bulkhead is fabricated as a monolithic structure. Optionally, alternatively, the annular internal bulkhead is fabricated from a plurality of components that are mutually assembled together. 
     In another aspect, the present disclosure provides a method for manufacturing a jet engine air inlet arrangement that peripherally surrounds an air inlet of a jet engine, wherein the jet engine air inlet arrangement includes a front annular casing arrangement and a heating pipe arrangement disposed within a cavity provided within the front annular casing arrangement, wherein the heating pipe arrangement provides heating to the jet engine air inlet arrangement when in use, 
     wherein the method includes:
 
(i) arranging for the heating pipe arrangement to be supported onto an annular internal bulkhead that provides a back wall to the cavity;
 
(ii) arranging for the annular internal bulkhead to be fabricated from deformed metal sheet, and arranging for the annular internal bulkhead to include a plurality of radially disposed stiffening projections and recesses in the back wall, and arranging for the annular internal bulkhead to include inner and outer circumferential flanges behind the back wall that engage onto inside surfaces of the front annular casing arrangement, wherein the plurality of radially disposed stiffening projections and recesses result in the flanges being disposed at a distance of more than 60 mm behind the plurality of radially disposed stiffening projections and recesses.
 
     The proposed solution is also applicable to swirl thermal anti ice systems. Swirl thermal anti ice systems also contain a heating pipe arrangement that ejects air into the cavity. In such systems the hot air is ejected from feed air tube at one position. An ejection opening of the air tube is oriented into the circumferential direction of the cavity such that ejected hot air has a circumferential component allowing the hot air to swirl through the cavity thereby heating the front annular casing arrangement. 
     Embodiments of the present disclosure substantially eliminate or at least partially address the aforementioned problems in the prior-art, and provide a jet engine air inlet arrangement having a flatter and longer front annular casing arrangement and a light weight and structurally rigid annular internal bulkhead (or an optimized forward bulkhead). 
     Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments construed in conjunction with the appended claims that follow. 
     It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers. 
       Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein: 
         FIG. 1  is a schematic drawing of a jet engine, in accordance with an embodiment of the present disclosure; 
         FIG. 2  is a perspective view of an air inlet arrangement of the jet engine of  FIG. 1 , in accordance with an embodiment of the present disclosure; 
         FIG. 3  is an enlarged perspective view of a portion of the air inlet arrangement of  FIG. 2 , in accordance with an embodiment of the present disclosure; 
         FIG. 4  is an enlarged perspective view of a rear portion of the air inlet arrangement of  FIG. 2 , in accordance with an embodiment of the present disclosure; 
         FIG. 5  is a cross-sectional view of the air inlet arrangement of  FIG. 2  along an axis A-A′, in accordance with an embodiment of the present disclosure; and 
         FIG. 6  is a schematic view of a portion of an air inlet arrangement, in accordance with another embodiment of the present disclosure. 
     
    
    
     In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible. 
     In overview, embodiments of the present disclosure are concerned with a jet engine air inlet arrangement (referred to herein as “an air inlet arrangement” for conciseness) that peripherally surrounds an air inlet of a jet engine. The embodiments of the present disclosure are also concerned with a method for manufacturing the jet engine air inlet arrangement. The air inlet arrangement, when in operation, performs a plurality of functions: providing an air flow into the jet engine, inhibiting ice-formation on leading surfaces thereof, providing structural integrity to the jet engine and serving as an aesthetically pleasing component for the jet engine. Additionally, from an aerodynamic performance standpoint, the air inlet arrangement has a shape and dimensions that allow the air inlet arrangement to take full advantage of surface laminar flow benefits. 
     As aforementioned, the present disclosure provides an air inlet arrangement that peripherally surrounds an air inlet of a jet engine. The air inlet arrangement comprises various components, such as a front annular casing arrangement, a heating pipe arrangement and an annular internal bulkhead. The front annular casing arrangement is configured to have a flatter and a longer structural configuration compared to a contemporary conventional front annular casing arrangement. The flatter and longer structural configuration of the front annular casing arrangement enables more efficient de-icing for a larger area thereof to be achieved in operation. Furthermore, the front annular internal bulkhead is fabricated from a deformed metal sheet, which enables a weight if the bulkhead to be reduces, and hence an overall weight of the air inlet arrangement to be correspondingly reduced. Moreover, the front annular internal bulkhead has a non-planer structure, such as a form of corrugated structure, to provide the annular internal bulkhead with increased structural rigidity in comparison to a conventional planer front annular internal bulkhead. 
       FIG. 1  is a schematic drawing of a jet engine  100 , in accordance with an embodiment of the present disclosure. As shown, the jet engine  100  includes an air inlet arrangement  102  peripherally surrounding an air inlet  104  of the jet engine  100 . The air inlet arrangement  102  is an annular arcuate structure that surrounds the air inlet  104 . The air inlet arrangement  102  is operable to ensure a smooth airflow into the jet engine  100  through the air inlet  104 . Typically, the air inlet arrangement  102  is configured to have a shape that accommodates variable air speeds and a wide variation of incident air-flow attack angles to ensure smooth airflow supply (i.e. a uniform constant air-flow) into the jet engine  100 . The air inlet arrangement  102  includes a front annular casing arrangement  106  that acts as an outermost covering of the air inlet arrangement  102 . The front annular casing arrangement  106  forms a lip for the air inlet  104 . 
     Referring now to  FIG. 2 , there is illustrated a perspective view of the air inlet arrangement  102  of the jet engine  100  (shown in  FIG. 1 ), in accordance with an embodiment of the present disclosure. As shown, the air inlet arrangement  102  includes a heating pipe arrangement  200  disposed within a cavity  202  provided within the front annular casing arrangement  106 . Typically, the heating pipe arrangement  200  is placed along a circumference of the air inlet arrangement  102 . As shown, the air inlet arrangement  102  also includes an annular internal bulkhead  204 . The annular internal bulkhead  204  supports the heating pipe arrangement  200  thereon. The annular internal bulkhead  204  provides a back wall to the cavity  202 . The annular internal bulkhead  204  includes a plurality of radially disposed stiffening projections, such as stiffening projections  206 , and recesses, such as recesses  208 , in the back wall. 
     As shown in  FIG. 2 , the annular internal bulkhead  204  is configured to support to the heating pipe arrangement  200  thereon using a plurality of stiffeners  210 . The plurality of stiffeners  210  are placed at regular intervals along the annular internal bulkhead  204  for rigidly mounting the heating pipe arrangement  200  onto the annular internal bulkhead  204 . 
     Referring now to  FIG. 3 , there is illustrated an enlarged perspective view of a portion of the air inlet arrangement  102  of  FIG. 2 , in accordance with an embodiment of the present disclosure. Specifically, in  FIG. 3 , there is illustrated a perspective cross-sectional view of a portion of the air inlet arrangement  102  of  FIG. 2 . As shown, the front annular casing arrangement  106  constitutes the outermost protective cover of the air inlet arrangement  102 . According to an embodiment, the front annular casing arrangement  106  is configured to have an elliptical shape. Alternatively, optionally, the front annular casing arrangement  106  is configured to have triangular shape. The front annular casing arrangement  106  encompasses the heating pipe arrangement  200  and the annular internal bulkhead  204 . 
     As shown, the heating pipe arrangement  200  includes a heating tube  300 , particularly, a piccolo tube. In operation, the heating tube  300  functions to guide a flow of hot and high-pressure air therethrough for providing heat to the air inlet arrangement  102 , primarily for de-icing the front annular casing arrangement  106 . Typically, the flow of hot air is guided to be released from apertures (not shown) configured on the heating tube  300  for heating the front annular casing arrangement  106  and the annular internal bulkhead  204 . As aforementioned, the annular internal bulkhead  204  provides (or forms) a back wall for the cavity  202 ; accordingly, the annular internal bulkhead  204  and the front annular casing arrangement  106  function to retaining the heat, provided by the heating pipe arrangement  200 , substantially within the cavity  202 . 
     The heating tube  300  is mounted on the annular internal bulkhead  204  using stiffeners, such as a stiffener  210 . As shown, the stiffener  210  includes an annular recess (through which the heating tube  300  passes) and supporting tabs (configured to be mounted on the annular internal bulkhead  204 ). In particular, the supporting tabs of the stiffener  210  are configured to conform to a shape of the stiffening projection  206  for being mounted over the stiffening projection  206  using fasteners, such as screws, bolts or rivets. The stiffening projections  206  are shown to be separated or spaced apart by the recesses  208 . These stiffening projections  206  and the recesses  208  are radially disposed along the annular internal bulkhead  204  as shown. The stiffening projections  206  provide more structural rigidity to the annular internal bulkhead  204  in comparison to a conventional planner annular internal bulkhead. 
     Referring to  FIG. 4 , there is illustrated an enlarged perspective view of a rear portion of the air inlet arrangement  102  of  FIG. 2 , in accordance with an embodiment of the present disclosure. Specifically, in  FIG. 4 , there is depicted a feed pipe  400  of the heating pipe arrangement  200 , shown in  FIG. 3 . The feed pipe  400  is fluidically coupled to the heating tube  300  (shown in  FIG. 3 ) and is arranged perpendicularly to the heating tube  300 . The feed pipe  400  is operatively coupled to a hot air source for carrying the hot air from the hot air source and for delivering the hot air to the heating tube  300 . Generally, the hot air source may be a combustor or a compressor of the jet engine  100  (shown in  FIG. 1 ), depending upon a required temperature of the hot air. For example, the compressor is operable to compress the air entering into the jet engine  100  to a temperature in a range of 200 to 550° C., whereas the combustor exhaust air is capable of reaching a temperature of up to 2000° C. 
       FIG. 5  is a cross-sectional view of the air inlet arrangement  102  of  FIG. 2  along an axis A-A′, in accordance with an embodiment of the present disclosure. As depicted, the annular internal bulkhead  204  serves as the back wall to the cavity  202 . The annular internal bulkhead  204  includes inner and outer circumferential flanges  502 ,  504  that engage onto an inside surface  510  of the front annular casing arrangement  106  behind the back wall (i.e. formed by the annular internal bulkhead  204 ). According to an embodiment, the inner and outer circumferential flanges  502 ,  504  of the annular internal bulkhead  204  are optionally snap-fitted with the inside surface  510  of the front annular casing arrangement  106 . Alternatively, the inner and outer circumferential flanges  502 ,  504  are optionally coupled to the inside surface  510  using fasteners, such as screws, bolts or rivets. As shown, the plurality of radially disposed stiffening projections  206  and the recesses  208  (best shown in  FIG. 3 ) result in the inner and outer circumferential flanges  502 ,  504  being disposed at a distance of more than 60 millimetre (mm), more optionally more than 65 mm, behind the plurality of radially disposed stiffening projections  206  and the recesses  208 . Specifically, the front annular casing arrangement  106  of the present disclosure is configured to have a flatter configuration (as compared to a conventional front annular casing arrangement), therefore the annular internal bulkhead  204  is in aggregate arranged at a greater distance away from the heating pipe arrangement  200 . In other words, the front annular casing arrangement  106  is configured to have an extended length “X” as compared to a length of the conventional front annular casing arrangement. In an example, as shown in  FIG. 5 , the extended length “X” corresponds to the depth of the radially disposed stiffening projections  206  and the recesses  208 . Furthermore, the extended length “X” is optionally more than 60 mm, more optionally 65 mm, or may be 70 mm. 
     According to an embodiment, the extended length “X” of the front annular casing arrangement  106  provides an extra area for heating the air inlet arrangement  102 . It will be apparent that the extra area requires extra heat input to be provided by the feed pipe  400  (shown in  FIG. 4 ) to the heating pipe arrangement  200  to maintain a required rate of heating for de-icing the front annular casing arrangement  106 . 
     In an example, a distance between a tip of the front annular casing arrangement  106  and the annular internal bulkhead  204  is about 197.2 mm, i.e. 65 mm longer than a conventional length (of about 154.8 mm) of a BR725 D-Duct. Such a greater distance results in in the extended length “X” (or extended portion) of the front annular casing arrangement  106 . In order to compensate a gain in weight due to the extended length “X”, a width of the front annular casing arrangement  106  is reduced to a certain degree. In other words, the front annular casing arrangement  106  is made flatter and longer. 
     The annular internal bulkhead  204  is fabricated from deformed metal sheet. Optionally, the annular internal bulkhead  204  is fabricated from deep-drawn or super-plastic-deformed metal sheet. With superplastic forming, the metal sheet is inserted in a die cavity or a pressure chamber, and hot pressurized gas is applied evenly to deform the metal, whereas, for deep drawing a sheet metal blank is radially drawn into a forming die by the mechanical action of a punch. 
     More optionally, the metal sheet is fabricated from steel, Aluminium, an Aluminium alloy, Titanium or a Titanium alloy. According to an embodiment, typically, the annular internal bulkhead  204  has a weight of 18.394 kg. In this case, when the annular internal bulkhead  204  is made of Titanium sheet metal having a density of about 5410 kg/m 3  and a thickness of about 1.2 mm, the annular internal bulkhead  204  has a weight of 9.382 kg, i.e. 49% less than the weight of 18.394 kg. Alternatively, when the annular internal bulkhead  204  is made of Titanium sheet metal having a density of about 5410 kg/m 3  and thickness of about 1.6 mm, the annular internal bulkhead  204  has a weight of 12.509 kg, i.e. 32% less than the weight of 18.394 kg. It will be evident that the lower weight of the annular internal bulkhead  204  thereby achieved enables a functional efficiency of the jet engine  100  to be increased. Additionally, it will be apparent that the annular internal bulkhead  204  optionally has other structural and/or compositional values, for example the metal sheet optionally has a density in a range of 5300 kg/m 3  to 5500 kg/m 3 , and optionally has a thickness in a range of 1 mm to 2 mm. 
     Optionally, the annular internal bulkhead  204  is fabricated as a monolithic structure. Alternatively, optionally, the annular internal bulkhead  204  is fabricated from a plurality of components that are mutually assembled together. For example, the annular internal bulkhead  204  is optionally either made of a single piece of sheet metal or four pieces of sheet metal that are assembled together. 
     More optionally, the front annular casing arrangement  106  and the annular internal bulkhead  204  are fabricated as a monolithic structure, Alternatively, optionally, the front annular casing arrangement  106  and the annular internal bulkhead  204  are fabricated as separate components that are assembled together. 
       FIG. 6  is a schematic view of a portion of an air inlet arrangement, such as the air inlet arrangement  102 , in accordance with another embodiment of the present disclosure. As shown, the front annular casing arrangement  106  is provided with a plurality of perforations  600  in fluidic communication with the cavity  202 . The perforations  600  are fabricated on at least an external surface of the front annular casing arrangement  106 . In other words, the perforations  600  are provided peripherally around the front annular casing arrangement  106 . The perforations  600  provide, when in use, heating of an external surface of the front annular casing arrangement  106  leading into the air inlet  104  (shown in  FIG. 1 ) of the jet engine  100 . Such heating melts ice particles that are susceptible to accumulating on external surface of the front annular casing arrangement  106 , thereby keeping the external surface free of ice. 
     As shown, the incoming cold air depicted with solid arrows and the hot air coming out of the perforations  600  is shown with dotted arrows. The cold air mixes with the hot air but still a certain degree of heating is provided by the hot air over the front annular casing arrangement  106  for de-icing thereof. It will be apparent that the perforations  600  are an additional benefit of providing the extended length “X” of the front annular casing arrangement  106  for achieving efficient de-icing. 
     In an example, the perforations  600  are specially fabricated using special manufacturing techniques such as, but not limited to, electron beam machining and laser beam machining. The fabrication of the perforations  600  is implemented in a manner such that drag force generated from an entrained mass of air is sufficient to negate formation of ice on the perforations  600 . Furthermore, the arrangement and configuration (shape and dimension) of the perforations  600  are selected in a manner so as to provide an effective uniform heating to the front annular casing arrangement  106  to inhibit ice-formation over the leading edges. 
     According to an embodiment, the perforations, when in use, also potentially enable a reduction in engine noise by causing acoustic radiation dissipation. 
     The present disclosure also relates to a method for manufacturing a jet engine air inlet arrangement that peripherally surrounds an air inlet of a jet engine, wherein the jet engine air inlet arrangement includes a front annular casing arrangement and a heating pipe arrangement disposed within a cavity provided within the front annular casing arrangement, and wherein the heating pipe arrangement provides heating to the jet engine air inlet arrangement when in use. The method comprises arranging for the heating pipe arrangement to be supported onto an annular internal bulkhead that provides a back wall to the cavity. The method also comprises arranging for the internal bulkhead to be fabricated from deformed metal sheet, and arranging for the internal bulkhead to include a plurality of radially disposed stiffening projections and recesses in the back wall, and arranging for the internal bulkhead to include inner and outer circumferential flanges behind the back wall that engage onto inside surfaces of the front annular casing arrangement, wherein the plurality of radially disposed stiffening projections and recesses result in the flanges being disposed at a distance of more than 60 mm behind the plurality of radially disposed stiffening projections and recesses. 
     It will be evident that the method relates to the manufacturing of the jet engine air inlet arrangement, such as the air inlet arrangement  102 , that peripherally surrounds the air inlet, such as the air inlet  104 , of the jet engine, such as the jet engine  100  (as shown in  FIG. 1 ). Therefore, various embodiments and variants disclosed regarding the air inlet arrangement  102  above apply mutatis mutandis to the method. 
     Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.