Abstract:
A turbine engine compressor design utilizing multiple component integration, thereby reducing the number of required engine components. In conventional compressor designs, a multiple component system makes it difficult to predict the structural behaviors due to thermal and mechanical loading during transient conditions. The compressor design of the present invention has three main parts: a forward bearing housing, a bell-mouth (heat shield) and a coupled impeller shroud/diffuser. Such a design achieves the design objectives of the present invention, including reducing weight, reducing cost, minimizing tolerance build up and improving aerodynamic performance by utilizing multiple component integration for multiple modes of engine operation.

Description:
This invention was made with Government support under contract number N00019-01-C-3002 with outside funding from Lockheed Martin—U.S. government under the Joint Strike Fighter (JSF) program. The Government has certain rights in this invention 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates an engine compressor and, more specifically, to a turbine engine compressor utilizing multiple component integration, thereby reducing the number of required engine components. 
     Referring to  FIG. 1 , there is shown a conventional small gas turbine engine  100 . Intake air is taken into engine  100  as shown by arrows  102 . The intake air passes through a compressor wheel  104 . As air passes through the compressor section  106 , it is accelerated outwards at high speeds. The accelerated air is slowed down in a diffuser  108 , which comprises a ring of static vanes. A portion of the accelerated air may be used in a combustion chamber  110 , and a portion of the accelerated air may be used to drive other cold turbines or to pressurize aircraft cabins. Engine  100  is powered by burning fuel in combustion chamber  110 , heating the air flowing into engine  100 , causing it to expand and gain kinetic energy. The hot gases generated by the combustion process drive one or more turbine wheels  112  to create mechanical power that may be used, for example, to drive compressor wheel  104 . 
     Conventional compressor design includes multiple components, including an inner housing  114  to hold bearing requirements, an outer housing  116  to carry the carcass load, an inlet plenum  118 , a separate bell mouth  120 , a diffuser  108  and compressor wheel  104 . A multiple component system makes it difficult to predict the structural behaviors due to thermal and mechanical loading during transient conditions. Holding tighter clearances between components becomes impossible due to the manufacturing tolerance build up among the various components. Such a multiple component approach will not meet the light weight requirements of high-performance aircraft engines, such as typical fighter jet engines. 
     The power and thermal management system (PTMS) of high-performance aircraft has technical challenges that require a novel approach in the design of the compressor module. The turbine engines of these high-performance aircraft operate as a typical auxiliary power unit (APU) on the ground in an open-loop, fired mode and transitions to a closed-loop mode using main propulsion engine bleed air for power. These two modes of operation both require optimal clearance control between the rotating group and the static structure of the engine. 
     As can be seen, there is a need for a new design concept for a compressor housing of a gas turbine engine that minimizes weight, cost and tolerance build up by utilizing multiple component integration to maintain the optimum engine performance under both the open-loop, fired mode and the closed-loop mode of operation. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a compressor module for a turbine engine comprises an external housing having a forward end and an aft end; having multiple inlets such as an open mode inlet duct and a closed mode inlet duct in the external housing; a forward bearing housing conically extending from the forward end of the external housing and into the external housing; and a bell mouth circumferentially disposed within the external housing. 
     In another aspect of the present invention, a compressor for a gas engine comprises an external housing having a forward end and an aft end, an open mode inlet duct and a closed mode inlet duct in the external housing, a forward bearing housing conically extending from the forward end of the external housing and into the external housing, a bell mouth circumferentially disposed within the external housing, a forward flange on the forward end, and an aft flange on the aft end; a compressor wheel rotatably disposed at the aft end on a shaft; and a compressor shroud/diffuser disposed circumferentially about the compressor wheel; wherein the bell mouth and the compressor wheel provide an air path for air to flow to the rotatable compressor wheel and to be discharged into a compressor discharge scroll at an increased pressure from a pressure at the inlet duct. 
     In yet another aspect of the present invention, a compressor for a gas turbine engine of an aircraft comprises an external housing having a forward end and an aft end, an open mode inlet duct and a closed mode inlet duct in the external housing, a forward bearing housing conically extending from the forward end of the external housing and into the external housing, a bell mouth circumferentially disposed within the external housing, a forward flange on the forward end, and an aft flange on the aft end; a compressor wheel rotatably disposed at the aft end on a shaft; a compressor shroud/diffuser disposed circumferentially about the compressor wheel, wherein the bell mouth and the compressor wheel provide an air path for air to flow to the rotatable compressor wheel and to be discharged into a compressor discharge scroll at an increased pressure from a pressure at the inlet duct; a hole in an apex portion of the conically extending forward bearing housing, wherein the shaft extends from the compressor wheel through the hole; a forward bearing disposed within the forward bearing housing, the forward bearing providing axial and radial support of the shaft extending through the hole of the forward bearing housing; a speed sensor for measuring the speed of rotation of the shaft; a generator housing attached to the single forward flange; and a generator within the generator housing, the generator converting rotational energy of the shaft into electrical energy. 
     In a further aspect of the present invention, a gas turbine engine comprises a compressor module having an external housing with a forward end and an aft end, an open mode inlet duct and a closed mode inlet duct in the external housing, a forward bearing housing conically extending from the forward end of the external housing and into the external housing, a bell mouth circumferentially disposed within the external housing, a forward flange on the forward end, and an aft flange on the aft end; a combustion section attached at the aft end of the external housing; a generator housing attached at the forward end of the external housing; and a generator within the generator housing. 
     In still a further aspect of the present invention, a gas turbine engine used as an auxiliary power unit for an aircraft comprises a compressor module having an external housing with a forward end and an aft end, an open mode inlet duct and a closed mode inlet duct in the external housing, a forward bearing housing conically extending from the forward end of the external housing into the external housing, a bell mouth circumferentially disposed within the external housing, a single forward flange on the forward end, and a single aft flange on the aft end; a compressor scroll attached at the aft end of the external housing; a generator housing attached at the forward end of the external housing; a generator within the generator housing; a shaft extending from the combustion section, through the compressor module and into the generator housing; a compressor wheel rotatably disposed at the aft end on the shaft; a compressor shroud/diffuser disposed circumferentially about the compressor wheel; a hole in an apex portion of the conically extending forward bearing housing, wherein the shaft extends from the compressor wheel through the hole; a forward bearing disposed within the forward bearing housing, the forward bearing providing axial and radial support of the shaft; and a speed sensor for measuring the speed of rotation of the shaft; wherein the bell mouth and the compressor wheel provide an air path for air to flow to the rotatable compressor wheel and to be discharged into a compressor discharge scroll at an increased pressure from a pressure at the inlet duct. 
     In yet a further aspect of the present invention, a method of providing auxiliary power with a gas turbine engine comprises 1) providing a compressor module having an external housing with a forward end and an aft end, an open mode inlet duct and a closed mode inlet duct in the external housing, a forward bearing housing conically extending from the forward end of the external housing into the external housing, and a bell mouth circumferentially disposed within the external housing; 2) attaching a generator housing at the forward end of the external housing; 3) providing a generator within the generator housing; 4) attaching a combustion section attached at the aft end of the external housing; 5) extending a shaft from a turbine in the combustion section, through the compressor module and into the generator housing; 6) rotatably disposing a compressor wheel at the aft end on the shaft; 7) circumferentially disposing a compressor shroud/diffuser about the compressor wheel; 8) rotating the shaft to provide mechanical rotational power to the generator; and 9) converting the mechanical rotational power to electrical power. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially cut-away cross-sectional view of a conventional gas turbine engine; 
         FIG. 2  is a schematic cross-sectional view of a high-performance gas turbine engine of the present invention; 
         FIG. 3  is an isometric view of a compressor module according to the present invention; and 
         FIG. 4  is a cross-sectional view showing the compressor module of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. 
     Broadly, the present invention provides for a compressor of a gas engine, such as a gas turbine engine, having the number of components reduced, as described below, by at least one component and up to four components. Such a design allows for a reduction in weight. A reduced number of components allows the components to be arranged in close tolerance. In conventional compressor designs, the components may vary in material and, thus, vary in heat capacities. Such variation requires additional component tolerances because one material may thermally expand differently as compared to another component. Further, manufacturing variances between the components require additional component tolerances in order to account for these manufacturing variations. 
     More specifically, the present invention provides a compressor having three main parts, whereas prior designs typically employ seven main parts: an inner housing to hold the bearing requirements, an outer housing to carry the carcass load, an inlet plenum with a single inlet, a separate bell mouth, an impeller shroud, a diffuser and an impeller. As will be discussed in more detail below, the compressor of the present invention includes a forward bearing housing, a bell-mouth (heat shield), and an impeller shroud/diffuser. The forward bearing housing integrates the functions of the conventional inner housing, outer housing and inlet plenum. As is described in more detail below, this single part will carry engine carcass loads between the generator housing and the compressor discharge scroll. Such a design achieves the objectives of the present invention, including reduced weight, reduced cost, minimized tolerance build up, and improved aerodynamic performance by utilizing multiple component integration. 
     Referring to  FIG. 2 , there is shown a cross-sectional view of a gas turbine engine  10  according to the present invention. Broadly, engine  10  may include a combustion module  12 , a compressor module  14 , a generator housing  16 , and a cool turbine  18 . Engine  10  can be especially useful when used as a typical auxiliary power unit (APU) in a high-performance jet aircraft. When the aircraft is on the ground, engine  10  may operate in an open-loop, fired mode. In such mode, combustion module  12  may provide hot combustion gases which, in a manner similar to the conventional gas turbine engine previously described, may drive a generator  20  and a compressor wheel  22 . During aircraft flight, engine  10  may operate in a closed-loop mode, using main propulsion engine bleed air for power in such mode, bleed air from the main propulsion engine (not shown) can be routed to drive turbine wheel  23  which, in turn, can rotate a shaft  24  that drives generator  20 . 
     Referring to  FIGS. 3 and 4 , there are shown multiple views of compressor module  14 . A single aft flange  30  may connect compressor module  14  to combustion module  12  (FIG.  2 ). A single forward flange  32  may connect compressor module  14  to generator housing  16 . 
     Compressor module  14  can include an external housing  34  having an open mode inlet duct  36  for air inlet during operation of engine  10  in the open-loop mode as described above. A closed mode inlet duct  38  can be provided in external housing  34  for inlet air feed during operation of engine  10  in the closed-loop mode as described above. The inlet air feed during the closed-loop mode may be engine bleed air from the main propulsion engine (not shown). The outer surface of external housing  34  may provide mounting for various external control devices and ancillary installation hardware, such as a speed sensor  42 , as described below. 
     A speed sensor insertion manifold  40  may also be formed as a cylinder through both wall of external housing  34  and forward bearing housing  52  to prevent oil leakage into the flow path and in external housing  34  for insertion of speed sensor  42  to measure the speed of rotation of a shaft  24 . Preferably, during operation of the high-performance aircraft, engine  10  is powered by main propulsion engine bleed air. 
     An inlet bell mouth  48  may be disposed within external housing  34  of compressor module  14 . Temperature differentials in compressor module  14  may result in different parts having different thermal expansion characteristics, thus requiring additional clearances and, therefore, resulting in a larger engine size. Bell mouth  48  is preferably formed circumferentially around compressor wheel  22 . 
     Forward bearing housing  52  may be formed within compressor module  14 . Forward bearing housing  52  may be formed in a conical shape with an apex  56  directed toward aft flange  40 . Apex  56  may have an opening  58  through which shaft  24  may be inserted. A forward bearing  54  may be housed within forward bearing housing  52 . Forward bearing  54  can provide axial and radial support where shaft  24  meets non-rotating components, such as generator  20  and compressor module  14 . Forward bearing housing  52  can integrate the functions of the inner housing with multiple inlet ducts  36  and  38 , outer housing and inlet plenum as found on conventional compressor modules as previously described. A second speed sensor manifold  41  can be formed in forward bearing housing  52 , in line with speed sensor manifold  40 , thereby permitting speed sensor  42  simultaneous insertion through both speed sensor manifold  40  and second speed sensor manifold  41 . 
     Shaft  24  may terminate at generator  20 . Generator  20  may be used as a typical APU or for starting larger engines. Generator  20  may employ a typical power turbine governing system (not shown) to regulate the speed of shaft  24  to drive loads requiring more consistent shaft speeds, such as AC generators. 
     A compressor shroud and/or diffuser  60  is provided downstream, as indicated by arrows  50 , of compressor wheel  22 . 
     The components of compressor module  14  may be made through typical manufacturing processes. For example, compressor shroud/diffuser  60  may be formed from a forged ring by machining and brazing. Forward bearing housing  52  may be made from investment casting. Bell mouth  48  may be made from sheet metal welded to a machined ring. The materials may be chosen from any metal suitable for the physical and mechanical stresses of compressor module  14 . For example, the components may be made from titanium, steel, aluminum composites, or stainless steel. Preferably, the components are made of titanium. 
     Compressor wheel  22  can be rotated either via rotating shaft  24  or via combustion and turbine expansion of pressurized air entering compressor module  14  via closed-mode inlet duct  38 . In either case, impeller blades  62  can be rotated, causing air to be pressurized as it moves along the path shown by arrows  50 . Compressed air can then be allowed to exit into a compressor discharge scroll  64 . This compressed air may be used to feed a combustor chamber, cool aircraft avionics system or to pressurize aircraft cabins. 
     In a method of providing auxiliary power with a gas turbine engine according to the present invention, it can be seen that compressor module  12  may be used to provide a source of auxiliary power. Generator  20  may be attached at forward flange  32  of external housing  34 . Combustion module  12  may be attached at aft flange  30  of external housing  34 . Shaft  24  may be extended from combustion module  12 , through compressor module  14  and into generator  20 . Compressor wheel  22  is rotatably disposed at the end of shaft  24 , opposite combustion module  12 . A compressor shroud and/or diffuser  60  may be circumferentially disposed about compressor wheel  22 . Shaft  24  may be rotated by turbine wheel  23  in the combustion module  12  to provide mechanical rotational power to generator  20 , which converts this mechanical rotational power to electrical power. 
     It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention.