Gas turbine engine flow path geometry

A flow path surface of a gas turbine engine at the location of a bladed component is disclosed in which the flow path surface includes a cylindrical upstream side and a conical downstream side. The bladed component is located at the intersection of the cylindrical upstream side and the conical downstream side. The cylindrical upstream side can extend from a leading edge of the bladed component, or a point upstream of it, to a location between the leading edge and trailing edge of the component. The conical downstream side can extend past the trailing edge of the bladed component. The bladed component can be a fan blade or a compressor blade.

TECHNICAL FIELD

The present invention generally relates to gas turbine engine flow paths, and more particularly, but not exclusively, to gas turbine engine flow path geometry.

BACKGROUND

Providing flow paths through a gas turbine engine that have acceptable performance characteristics remains an area of interest. Some existing systems have various shortcomings relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology.

SUMMARY

One embodiment of the present invention is a unique gas turbine engine flow path surface. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for directing the flow through a turbomachinery component in the vicinity of a blade. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

With reference toFIG. 1, one embodiment of a gas turbine engine50is shown having turbomachinery components52and56as well as a combustor54. During operation, a working fluid such as air is received by the gas turbine engine50and is compressed and mixed with a fuel prior to being combusted and expanded to produce work. The gas turbine engine50can be configured as an adaptive and/or variable cycle engine and can take any variety of forms in other embodiments such as a turboshaft, turbofan, or turboprop, or turbojet. Thus, the gas turbine engine50can be a single spool engine as is depicted inFIG. 1, but in other embodiments the gas turbine engine50can include additional spools.

The turbomachinery component52depicted inFIG. 1is in the form of a compressor, and although the turbomachinery component52is shown as a single component, in some forms the gas turbine engine50can include multiple turbomachinery components52. For example, in one non-limiting embodiment the gas turbine engine50can include a turbomachinery component52in the form of a fan as well as a turbomachinery component52in the form of a compressor stage. The fan can be a single or multi stage fan, and the compressor stage can be a single or multi stage compressor. In some forms the fan stage can be driven by a low pressure spool and the compressor stage can be driven by a higher pressure spool, among any variety of other possibilities. No limitation of the gas turbine engine50is hereby intended given the schematic representation illustrated inFIG. 1. As will be appreciated, the turbomachinery component52can include a plurality of rotating blades and in some forms can include a plurality of stator vanes. In some forms the turbomachinery component52can include multiple rows of blades and/or multiple rows and stator vanes. The stator vanes can be static and/or variable.

The gas turbine engine50can be used to provide power to an aircraft (not illustrated). As used herein, the term “aircraft” includes, but is not limited to, helicopters, airplanes, unmanned space vehicles, fixed wing vehicles, variable wing vehicles, rotary wing vehicles, unmanned combat aerial vehicles, tailless aircraft, hover crafts, and other airborne and/or extraterrestrial (spacecraft) vehicles. Further, the present inventions are contemplated for utilization in other applications that may not be coupled with an aircraft such as, for example, industrial applications, power generation, pumping sets, naval propulsion, weapon systems, security systems, perimeter defense/security systems, and the like known to one of ordinary skill in the art.

Turning now toFIG. 2, one embodiment is depicted of the turbomachinery component52having a blade58that rotates about the centerline and an outer wall60disposed radially outward of the blade58. As will be understood given the discussion above, the blade58can be either a compressor blade or a fan blade. The outer wall60is used to form a flow path for the working fluid62that passes through the turbomachinery component52. The outer wall60can take the form of a structural component of the gas turbine engine50, for example in some applications the structure component is a casing of the gas turbine engine50. In other forms the outer wall60can be a component used to form a flow path surface that is attached to a structural component of the gas turbine engine50, or intermediate load transferring component of the gas turbine engine50. For example, a component used to create a flow path surface can take the form of a liner that is attached to and offset from a casing of the gas turbine engine50. In some applications the liner can be a fan liner, they casing can be a fan casing or compressor casing, etc. In short, the outer wall60can take a variety of forms.

The outer wall60generally includes a cylindrical upstream portion64, a transition66, and a conical downstream portion68. The union of these two geometric shapes across the axial tip of the blade58provides at transonic flow conditions an increase in total blade area within the blade passage before the passage shock relative to a purely cone-shaped casing. This configuration provides two approximate design options: either actual flow within the blade passage is increased relative to a conventional configuration, or optionally the blade baseline airflow can be maintained via blade closure, leading to a reduction in specific flow due to the increase in blade passage area before the passage shock for the same actual flow. If, in conjunction with the casing, the baseline blade flow is maintained as per the second design approach, then due to the reduction in effective specific-flow the blade typically exhibits an improvement in efficiency at operating points such as cruise and take-off. The baseline flow rate can be maintained by increasing the stagger-angle parameter of either all or a subset of the blade airfoil sections or by reducing the camber of either all or a subset of the blade airfoil sections. In one embodiment, a baseline blade flow rate is maintained by increasing the blade tip stagger-angle and linearly blending the change in stagger-angle to zero at the blade hub.

The cylindrical upstream portion64can start at any axial location forward of a leading edge70of the blade58and generally extends aft to the transition66which is located between the leading edge70and a trailing edge72of the blade58. In the illustrated embodiment the cylindrical upstream portion64starts at location74which is forward of location76associated with the leading edge70of the blade58. In other embodiments the cylindrical upstream portion64starts at the axial location of the leading edge70, thus location74and location76are axially coincident. In one alternative and/or additional embodiment, the axial extent of the cylindrical upstream portion64, shown as distance B inFIG. 2, is approximately ¼ of the distance between location76and location73associated with the trailing edge72of the blade58, shown as distance A inFIG. 2.

As used herein the term “cylindrical” includes surfaces that have a constant radius relative to a reference axis along the entirety of the circumference and the entirety of the axial reach of the cylindrical surface. The term also includes surfaces that are substantially cylindrical, either partially or in whole, around the circumference and axial reach of the cylinder. Non-limiting examples of substantially cylindrical include surfaces that have some amount of variation introduced through design, manufacturing, wear, etc.

The outer wall60changes from the cylindrical upstream portion64to the conical downstream portion68through the transition66which is denoted for convenience as location79. The transition66can be formed as the result of a manufacturing operation such as, for example, milling, casting, molding, etc. The transition66could also represent a joint between separately constructed components fastened to reside next to one another to form the cylindrical upstream portion64and conical downstream portion68. Thus, the outer wall60can be one integral structure or can be an integrated assembly.

The transition66between the cylindrical upstream portion64and the conical portion can have any shape and can be as abrupt as desired which may take into account manufacturing considerations/tolerances, flow phenomena considerations, etc. Setting forth just a few non-limiting forms, the transition can be a sharp corner in some applications, it can include a smoothed corner, such as a rounded or filleted corner, in other applications, etc. A rounded transition can, but need not, be at a constant radius and/or be centered about a point at which the cylindrical surface meets the conical surface. Other arrangements are also contemplated, such as, but not limited to, a rounded transition that extends further in either the forward or aft direction relative to the other direction.

As the flow path changes from cylindrical to conical it transitions from a surface having very little, if any, contraction, to a surface having a constant contraction once established on the conical surface. Throughout the transition66, however, the contraction rate can be variable. As will therefore be appreciated, the flow path surface of the outer wall60experiences a rate of contraction that varies and will increase or stay the same over the entire axial length of the structure. In the particular form of a rounded corner at the transition66, the initial contraction rate is relatively low and once a transition to the conical surface is complete the contraction rate is at its highest.

The blade58in the illustrated embodiment includes a tip shape that follows the contour of the outer wall60. Thus, the blade58includes a forward portion78and an aft portion80that mimic the slopes of the cutaway view of the outer wall60. Not all embodiments need include forward portions78and/or aft portions80that precisely mimic the slopes of the outer wall60. An offset of the blade58from the outer wall60over the forward portion78can be constant, as can be an offset of the blade58from the outer wall60over the aft portion80. Furthermore, the offset over the forward portion78can, but need not, be the same as the offset over the aft portion80.

A blade transition82between the forward portion78and aft portion80can be placed at location77such that it is located axially forward, axially aft, or with any portion of the transition66. In the illustrated embodiment the location77of the blade transition82is located forward of the location79of transition66. In one non-limiting embodiment, the axis of the first torsion mode of the blade58is located with the transition66.

The conical downstream portion68begins after the transition66and generally extends aft past the trailing edge72of the blade58to location83in the illustrated embodiment. In one form the conical downstream portion68extends a fraction of the axial chord-length of the blade58past the location73. As used herein the term “conical” includes frustoconical surfaces that have a linear sloping surface around the entirety of the circumference and the entirety of the axial reach of the frustoconical surface. The term also includes surfaces that are substantially linearly sloping, either partially or in whole, around the circumference and axial reach of the surface. Non-limiting examples of substantially frustoconical include surfaces that have some amount of variation in the sloping surface introduced through design, manufacturing, wear, etc. In one non-limiting embodiment, the slope of the linear sloping surface is about nine degrees as measured relative to a reference line, such as the centerline of the engine.

Turning now toFIG. 3, one embodiment of a joint between the cylindrical upstream portion64and the conical downstream portion68is shown. The transition66is illustrated as a rounded corner that extends forward and aft of the location79of the transition66. An intersection84is illustrated and represents a location at which the cylindrical upstream portion64, if continued past the transition66, would intersect the conical downstream portion68if it continued forward of the transition66. Thus, the intersection of the upstream portion64and downstream portion68is offset from a flow surface of the transition66. The offset can be any distance depending on the nature of the transition66. In some forms the intersection may not be offset. For example, in the case of an integrated outer wall60constructed of separate upstream portion64and downstream portion68, the intersection84can be at the flow path surface.