Patent Abstract:
Fluid release apparatus ( 26 ) for the release of fluid from the interior of a rotating and/or pressurized body ( 16;18;102;104 ), the apparatus comprising a core member ( 28 ) having a chamber wall ( 44 ) disposed thereabout so as to define an open chamber ( 30 ) about said core member. The apparatus further comprises a chamber closure ( 48 ) mounted about said core member ( 28 ), said closure being resiliently deformable between an at rest state in which the closure contacts the chamber wall ( 44 ) and an actuated state in which the closure is spaced there-from, wherein the chamber has an aperture ( 32;35;55 ) for receiving liquid phase fluid from the interior of said rotating body. Upon build up of sufficient liquid in said chamber ( 30 ) the closure ( 48 ) moves to said actuated state so as to release liquid from the interior of the body.

Full Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to fluid release apparatus and more particularly, although not exclusively, to a valve for releasing unwanted fluid build-up from an operational portion of a machine. 
     The description of the present invention proceeds with reference to rotating machinery, such as, for example, gas turbines. It is known in the art to make allowance for the escape of unwanted liquid from the interior of a compressor drum within a gas turbine. Unwanted liquid may gather for a number of reasons, including malfunction or failure of one or more seals or else the ingress of water from outside of the engine. 
     During operation, the rotating compressor drives air into the combustor downstream and the compressor drum is maintained at an elevated pressure. A compressor rotor configuration typically comprises a plurality of discs, each having a set of rotor blades mounted thereto. 
     In a conventional turbine compressor, it is known to provide axial drainage holes in the discs of the compressor drum so as to allow for the escape of liquid from the interior of the compressor. Axially oriented drainage passages in the form of inter-disc holes convey the liquid to be expelled via an exit drainage opening at a radially outermost portion of the drum. The centrifugal force acting on the liquid in the compressor drum serves, at least in part, to drive the unwanted liquid to the final exit drainage points. 
     The exit drainage opening connects to an area of lower pressure such that in normal engine operation, there is typically a constant leakage of high pressure air through the final exit drainage hole. Whilst the flow of air in this manner encourages the passage of liquid along the drainage path, the ultimate leakage of this air at the drainage point represents an unwanted loss of efficiency to the system. 
     SUMMARY OF THE INVENTION 
     It is an aim of the present invention to provide a device for releasing a first fluid from the interior of a rotating body whilst mitigating the problem of loss of further fluids there-from. 
     According to one aspect of the present invention there is provided fluid release apparatus arranged for the release of fluid from the interior of a rotating body, the apparatus comprising a chamber wall disposed about an aperture in the rotating body so as to define an open chamber about said core member, and a chamber closure being resiliently deformable between an at rest state in which the closure contacts the chamber wall and an actuated state in which the closure is spaced there-from, wherein the chamber is arranged to receive liquid phase fluid from the interior of said rotating body such that upon build up of sufficient liquid in said chamber the closure moves to said actuated state so as to release liquid from said rotating body under centrifugal force. 
     The rotating body may be maintained at an elevated pressure. In one embodiment, the fluid release apparatus takes the form of a device which is arranged for location in a flow path between a region of relatively higher pressure in the interior of the rotating body and a region of relatively lower pressure outside of said body. 
     The chamber may be arranged to receive both liquid and gas phase fluids from the interior of the rotating body. The fluid release device may provide the benefit of releasing fluid of one phase in preference to another. Preferably the device allows for release of liquid phase fluid in preference to gas phase fluid. 
     Typically the closure returns to its at rest state after release of some or all of the liquid in the chamber. The closure may be formed of a spring material and may take the form of a disk spring. 
     The apparatus may comprise a core member, which may be mounted to an external facing wall of the rotating body. The core member may be located in the aperture of the rotating body. The core member may be shaped to define a flow path between the interior of the rotating body and the chamber. 
     In one embodiment, the closure is fixed to or integral with the core member. The closure may extend radially outward from the core member. The closure may be substantially circular in plan. In one embodiment the closure may be generally annular or disc-shaped. 
     The chamber wall may surround the core member and may be curved in plan. The chamber wall may be circular in plan. 
     The chamber aperture may be provided in the base of the chamber. The chamber wall and base may be integrally formed. The base may be locatable against an outer surface of a wall of the rotating body. 
     The core member may have one or more ducts therein to allow for passage of fluid there-through. The core member may have a duct arranged to be aligned with an opening in the rotating body. The core member may be received within the aperture in the chamber such that fluid from the body enters the chamber via said core member. The core member may have a main duct with one or more ports depending outwardly there-from for passage of fluid from the inside of the core member into the chamber. 
     The chamber wall may define a first chamber and the device may comprise one or more formations within the first chamber defining a second chamber in fluid communication with said first chamber. The one or more formations may comprise an internal chamber wall about the core member. The internal wall may depend from the base of the first chamber or the closure. 
     The internal wall may have one or more ports therein for communication between the first and second chambers. Such ports may take the form of slots. The angular alignment and/or spacing of the ports in the internal wall may be in-line or offset from the ports in the core member. This facilitates the assembly of the device since steps do not need to be taken to ensure the slots  56  and the ports  55  are aligned for use. In addition, the presence of liquid in the inner chamber  54  may help prevent flow of air into the device and thus reduce any unwanted leakage of gas. 
     The internal volume of the second chamber may be less than that of the first chamber. The second chamber may be contained within the first chamber. The first and second chamber may be arranged about a common centre. The second chamber may be curved or circular in plan. 
     According to a preferred embodiment, the closure has an aperture shaped to allow insertion of the core member there-through. The core member and/or closure member may have fixing formations thereon. The fixing formations may comprise a threaded section. The closure may be fixedly held in place about the core member by fixing means such as a nut. 
     The closure may comprise a collar portion for location about the core member and closure portion depending outwardly there-from. The collar may be shaped so as to define the second chamber about the core member. The collar may have a circumferential groove or recess on its inner surface which defines the second chamber. 
     The closure portion may have first and second opposing major faces the dimensions of which are substantially greater than thickness of the closure portion. The closure portion may be substantially planar or flat in shaped. 
     In one particular embodiment, one or more fluid exit ports may be provided in the chamber wall. A liquid release port may be provided towards the free edge of the chamber wall. A gas release port may be provided towards the base of the chamber wall. 
     According to a second aspect of the present invention there is provided fluid release apparatus arranged for location in a flow path between a region of relatively higher pressure within a body and a region of relatively lower pressure outside of said body, the apparatus comprising a core member having a chamber wall disposed thereabout so as to define an open chamber about said core member, and a chamber closure mounted about said core member, said closure being resiliently deformable between an at rest condition in which the closure contacts the chamber wall and an actuated condition in which the closure is spaced there-from, wherein the chamber has an aperture for receiving liquid phase fluid from the interior of said body such that upon build up of sufficient liquid in said chamber the closure moves to said actuated condition under pressure of liquid in the chamber so as to release liquid from said chamber. 
     Any of the preferable features described above in relation to the first aspect may also be applied to the second aspect of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more practicable embodiments of the present invention are described in further detail below by way of example with reference to the accompanying drawings, of which: 
         FIG. 1  shows a section view of the compressor arrangement in a generic three-shaft turbofan engine, indicating possible locations for the present invention; 
         FIG. 2  shows a section view of the compressor arrangement in a generic two-shaft turbofan engine, indicating possible locations for the present invention; 
         FIG. 3  shows a three-dimensional view of a fluid release device according to one embodiment of the present invention mounted in a compressor drum section; 
         FIG. 4  shows a section view taken through the centre of the device of  FIG. 3 ; and, 
         FIG. 5  shows a section view taken through the centre of a fluid release device according to a further embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention described below provide for a compact centrifugally activated release valve for a compressor. Those embodiments allow release of liquid (typically oil or water) from a compressor drum while the engine is running whilst substantially impeding the unwanted escape of air through the device. 
     Turning now to  FIG. 1 , there is shown a general arrangement of compressors in a ducted fan gas turbine engine, shown generally at  10 . The gas turbine engine  10  has a principal and rotational axis  12 . The engine  10  comprises, in axial flow series, a propulsive fan  14 , an intermediate pressure compressor  16  and a high-pressure compressor  18 . 
     The gas turbine engine  10  works in a conventional manner so that air entering the intake is accelerated by the fan  14  to produce two air flows: a first air flow into the intermediate pressure compressor  16  and a second air flow which passes through a bypass duct (not shown) to provide propulsive thrust. The intermediate pressure compressor  16  compresses the air flow directed into it before delivering that air to the high pressure compressor  18  where further compression takes place. The compressed air exhausted from the high-pressure compressor  18  is directed into combustion equipment where it is mixed with fuel and the mixture combusted. 
     The resultant hot combustion products then expand through, and thereby drive a series of high, intermediate and low-pressure turbines (not shown) before being exhausted to provide additional propulsive thrust. 
     Each of the intermediate  16  and high  18  pressure compressor rotors comprise a plurality of compressor stages, each stage having a circumferential series of compressor blades  20  mounted to a disc  22  as can be seen in the lower-left and lower-right detail sections of  FIG. 1 . The discs  22  are mounted in an axially spaced configuration with spacer sections  24  there-between so as to form the rotor drum. In  FIG. 1  it can be seen that an embodiment  26  of the present invention is arranged to be mounted to a circumferential outer wall of the rotor drum between adjacent discs  22 . 
     It is intended that one or more devices  26  according to the present invention may be mounted between some or all discs  22  of the intermediate or high pressure compressors. In one embodiment, a plurality of devices may be located in one or more inter-disc sections  24 . 
     Arrows A indicate the intended flow direction of fluid exiting the compressor drum via the devices  26 . 
     Turning now to  FIG. 2 , there is shown a general arrangement of compressors in a two-shaft ducted fan gas turbine engine, shown generally at  100 . It will be appreciated by a person skilled in the art that the bypass ratio of such an engine is lower than that of a three-shaft engine arrangement. The shape and arrangement of the low  102  and high  104  pressure compressors is different to that of  FIG. 1  in order to take account of the different bypass ratio and operational requirements. 
     However the general principal of compressor stages  106  mounted in an axially spaced configuration with spacer sections  108  there-between so as to form the rotor drum is similar to that of  FIG. 1 . Accordingly a device  26  according to the present invention may also be positioned in drum sections between or adjacent compressor discs in  FIG. 2  in a manner as described above in relation to  FIG. 1 . 
     It can be seen in the lower-left and lower-right detail sections of  FIG. 2 , the device  26  is mounted to the radially outer wall portion or ‘skin’ of the compressor drum. In this arrangement, arrows B indicate the intended flow direction of fluid exiting the compressor drum via the devices  26 . 
     Turning now to  FIG. 3 , there is shown a device  26  mounted on an outer wall section  24  of a rotating drum. The wall  24  and the device  26  are spaced from the axis of rotation of the drum. 
     The device generally comprises a core  28 , about which is located a chamber  30  as will be described in further detail below. 
     In  FIG. 4 , it can be seen that the wall  24  to which the device  26  is mounted comprises an opening  32 , in which the core member  28  is received. The core member  28  and opening  32  are correspondingly shaped such that the core fits closely within the opening  32 . 
     The core member  28  comprises a generally cylindrical body having a head portion  34  which takes the form of a flange which may be circular in plan. The flange serves as an abutment against the wall  24  which helps to ensure correct fixing of the device  26  to the wall  24 . The core member  28  extends through the wall  24  and terminates at its free end  36  a distance form the wall surface. 
     An anti-rotation formation  38  is provided towards the free end  36  of the core member. The formation  38  comprises an end portion of the core member which is generally rectangular in section as opposed to the generally cylindrical remainder of the core. 
     A passageway in the form of a bore  35  extends part-way into the body of the core member  28  from the head portion  34 . The bore  35  is open ended at the head end such that it opens into the interior of the drum wall  24 . 
     The core member is mounted such that it is in a radial orientation with respect to the rotational axis of the drum, with the head on the inside of the drum. The core may be considered to be similar to a modified bolt which may have a diameter of approximately 0.25″ (6.35 mm). 
     A chamber wall member  40  is located about the core member  28  so as to define in part the chamber  30 . The chamber wall member  40  comprises a base  42  and an upstanding wall  44  about the periphery of the base. The base is generally circular in plan and has an opening which may be located at its centre for reception of the core member  28 . In this embodiment the base  42  and side wall  44  are integrally formed as a unitary chamber wall member. The wall  44  is circumferential or annular in shape and defines a cavity  46  therein. Save for the opening at its centre, the chamber wall member has a shape akin to a pan or dish. 
     A closure  48  is located about the core member  28  and is seated on the chamber wall  44  so as to form a face of the closed chamber  30  as shown in  FIGS. 3 and 4 . The closure  48  has a closure portion  50  which is disc shaped having a central opening for reception of the core member  28 . The closure portion  50  is circular in plan and has a diameter slightly greater than that of the chamber wall  44  such that the closure lies over the wall. 
     The closure  48  in this embodiment has a supporting formation  52  disposed about the central opening in the form of an annular wall. The wall  52  is closely located about the core member  28  and is spaced from the outer periphery of the closure portion  50 . 
     The sectional shape of the wall  52  is profiled such that it defines a cavity  54  about the core member  28  when mounted for use. Thus the cavity  54  provides an inner cavity between the inner wall  52  and the core member  28 . This inner cavity  54  is generally annular and is formed in this embodiment by an inwardly-facing annular groove or recess in the inner wall  52 . In other embodiments, the wall may be otherwise tapered, shaped or oriented to provide a suitable inner chamber. 
     The wall  52  has one or more ports therein in the form of slots  56  to allow fluid communication between the inner chamber  54  and outer chamber cavity  46 . A pair of slots is provided in this embodiment, each slot being on opposing sides of the wall  52 , each spaced by 180°. The height and length of the slots are greater than the width thereof. This may assist in controlling the rate of flow there-through. 
     The closure portion  50  and wall  52  are integrally formed. The closure portion  50  is intended to function as a disc spring during operation such that it can be deflected upon application of a force thereto in a reversible manner. Thus once the deflection force is removed, the closure portion will return to its initial undeflected state. Various options for metal disc spring materials are known in the art and will not be described in detail here for conciseness. The closure  48  may be considered to be analogous to a washer with extra thickness around the central opening, the increased thickness forming a short tube which fits closely over the core member. 
     The core member  28  is provided with one or more ports  55  which pass into the passage  35 . The ports  55  may be radially aligned with respect to the axis of the core member and may be located towards the closed end of the passage  35 . A pair of opposing ports  55  may be provided, which may be offset from the slots  56  in the closure wall  52 . 
     The closure  48  and chamber wall member  44  are held in place against the drum wall  24  by way of a fixing member, which in this embodiment takes the form of a collar or nut  57 . A portion of the core member  28  is threaded in a manner to correspond with the nut  57 . 
     The nut clamps the assembly together. It screws on the end of the core member and bears against the outer face of the spring disc. As the nut is tightened, it provides a tension in the core member  28  which is opposed by the flange  34  so as to securely hold the chamber wall member  40  and closure  48  against the drum wall  24 . For aerospace turbomachinery applications it is expected that the nut would be an AS standard 0.250″ (or 6.35 mm) self locking nut although other sizes of nut and core member are also possible dependent on requirements. 
     In order to assemble the device according to the present invention, the core member  28  is first inserted through opening  32 . The chamber wall member  40  is then located on about the core member against the drum wall  24 . The closure  48  is then located about the core member  28  and slid into contact with the chamber wall member  40 . The nut is then applied to the assembly. The anti-rotation feature  38  on the core member enables full tightening torque to be applied to the nut. For easy access this would best be situated at the free end of the core member but could also be incorporated at the opposing end if access is available. 
     When the nut is sufficiently tightened, the closure is preferably pressed into contact with the upper edge of the wall  44 . Either the closure or wall may be shaped or otherwise provided with a seal-promoting formation to ensure an adequate seal is formed. 
     During operation, the compressor drum rotates and is maintained at an elevated pressure such that fluids contained in the drum will be forced through the passage  35  which is open to the drum interior. The head is as shallow as possible, bearing in mind its strength requirements, so that the minimum amount of liquid accumulates on the inside surface of the wall  24  prior to passage through the device. 
     The chamber  30  will normally be closed and will not allow any significant amount of air to pass through it. 
     The fluids entering the device may comprise one or more phases. Any or any combination of gas and/or liquid may enter the device through passage  35 . The relevant fluids in the case of a gas turbine will typically include air, water and/or oil. 
     The fluids entering the device pass along passage  35  and through port(s)  55  into the inner chamber  54 . The fluid then passes around the inner chamber until it passes through a slot  56  into the main chamber cavity  46 . When in the main cavity  46 , any liquid will tend to be forced against the inside surface of closure portion  50  under centrifugal force, whereas any gas in the chamber will tend to collect against the radially inner base  42 . Thus the gas and liquid phases will tend to separate by virtue of their different densities. 
     The liquid phase collecting against the closure portion  50  exerts a centrifugal force thereon by virtue of the rotation of the system. Once the force acting on the closure portion exceeds the resistive force of the closure material, the closure portion will move from its at rest state (shown in  FIG. 4 ) into a deflected state, wherein the circumferential edge of the closure is deflected away from the chamber wall  44 , leaving a small gap therebetween. The gap is generally uniform about the periphery of the chamber. 
     Liquid can then exit the device through the gap between the chamber wall  44  and the closure  48 , when deflected. As liquid escapes from the chamber, the centrifugal force on the closure will diminish until the spring force of the closure will return the closure portion  50  to its at rest state, thus preventing escape of further fluid from the device. The opening and closing of the chamber can be repeated under the action of fluid pressure to allow escape of liquid whilst substantially avoiding or minimising unwanted loss of gas from the drum interior. 
     It will be appreciated that the resistance of the closure  48  is important to the correct functioning of the present invention and may be tailored, for example by altering the thickness or profile thereof, in order to accommodate different applications in which the device may be used. Thus the spring characteristics of the closure  48  can be modified as required. The tensile strength of the closure is typically much greater than the force exerted on it during use such that the closure can be repeatedly deflected back and forth without yielding or permanently deforming. 
     The invention is scalable to suit a range of pressures, flow rates and/or rotational speeds, but except for very small or very large turbomachinery, the normal size for the invention would be designed to suit attachment to the engine with a single AS standard 0.250″ self locking nut (or metric equivalent). In addition the size of the chamber can be varied to suit particular applications. 
     A typical value for the centrifugal force acting upon the liquid in the main chamber for a gas turbine compressor would be in the region of 15000 G. Thus a large chamber volume of only 4 CC would generate a force the equivalent of 60 Kg (assuming the liquid to be water) acting uniformly on the area of the spring disc. This factor enables the invention to be compact. The chamber would optimally be configured to be relatively large in diameter and low in depth to accommodate the necessary volume of liquid. 
     Turning now to  FIG. 5 , there is shown a further embodiment of the invention which is substantially the same as the embodiment of  FIG. 3  save for the differences described below. 
     In  FIG. 5 , the form of the chamber wall member  60  and closure  162  are slightly different to that of  FIG. 4 . In particular the wall portion  52  of the closure has been omitted such that the closure  62  takes the form of a simple disc spring member which is generally planar in form. Instead of wall  52  in  FIG. 4 , the embodiment of  FIG. 5  has a supporting formation  64  which depends from the base  66  of the chamber wall member  60 . Thus the closure  62  is seated on the supporting formation  64  when the device is assembled for use. This may help reduce the manufacturing tolerance required for the closure. 
     The supporting formation  64  takes the form of a wall which may be integrally formed with the chamber wall member  60  and has slots  68  therein. In this embodiment, the slots are disposed adjacent the closure  62 , that is at a location spaced from the base  106 . 
     The assembly and operation of the device of  FIG. 5  are the same as that for  FIG. 4  and will not be repeated for conciseness. Any other features described in relation to  FIG. 4  may also apply to the embodiment of  FIG. 5 . 
     According to a further embodiment, an optional feature on the invention is the inclusion of an air/liquid release ports within the large chamber  40  or  60 . Such ports could be provided in the closure portion  50  or  62  or in the wall of the large chamber  44  or  100  and may take the form of one or more holes of diameter 0.5-2.0 mm. The function of such ports would be to allow gas such as air already in the chamber to be expelled when liquid is first forced in the large chamber and also to allow all liquid in the chamber to be expelled by centrifugal force even when there is insufficient liquid in the large chamber to actuate the spring disc into its ‘open’ state. 
     Whilst such a feature would allow a flow of air through the device in normal engine operation, the loss would be very small compared with conventional designs. 
     The preferred position for an air release hole may be at the base of the large chamber as indicated by numeral  58 . This is because air already present in the large chamber will be forced radially inwards due to liquid entering the large chamber which is flung outwards. If this is the case, liquid remaining after the valve has been activated (i.e. the amount of liquid just below the quantity that will open the valve), could remain trapped in the large chamber. This will not pose a serious problem to the operation of the device, but an additional port in the disc spring or rim of the large chamber would allow this liquid to escape. Thus a suitable port may be provided towards the free end of the chamber wall  44  or in the closure  50  in addition to, or instead of, the port  58 . 
     In a further alternative embodiment, the head portion of the core member may be modified in shape so as to provide fluid communication channels therein. This is to prevent the depth of the head portion inhibiting liquid entering the chamber of the fluid release device. Alternatively, the head portion may be unmodified and a washer having fluid channels therein, for example by way of undulations or the like, may be provided between the head and the drum wall  24 . 
     The invention as described above can prevent significant loss of air during normal engine operation and thus improve engine efficiency whilst allowing liquid to escape when liquid is present. The invention is lightweight even if all components are manufactured from steel and is reliable due to its simplicity of design and minimised number of moving parts. 
     Whilst the above description of the working embodiments shown in  FIGS. 1 to 5  is with reference to compressors for gas turbine engines in particular, it is to be noted that the device according to the present invention is not limited to such applications only. Instead the device of the present invention is broadly applicable to any applications in which it is desirable to release a fluid from a rotating and/or highly pressurised body. Instance in which the invention may be used could extend to other compressor or turbine arrangements, such as, for example in marine or power generation applications, other engine applications, such as internal combustion engines, separators, collectors or fluid handling equipment in other areas of industry.

Technology Classification (CPC): 5