Patent Application
20210172452
The present disclosure generally relates to centrifugal compressor impellers having nonlinear backwalls, and more particularly, but not exclusively, to centrifugal compressor impellers having backwalls with convex portions.
Providing improved stress and deflection performance on a centrifugal impeller 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.
One embodiment of the present disclosure is a unique centrifugal compressor impeller having at least a convex backwall. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for shaping nonlinear backwalls on centrifugal compressor impellers. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.
With reference to
The illustrated embodiment depicted in
Although not illustrated, when the impeller 56 is installed in the compressor system 50 a shroud is located outward of the compressor blades 60 such that a flow path is defined between the shroud and the hub 64 of the compressor. In this installed configuration a flow path entrance 66 at an axial end to an outlet 68 at a radial end. The entrance 66 can take the form of an inducer and the outlet 68 of an exducer. As will be appreciated, as the impeller rotates, fluid entering in an axial direction at the entrance 66 is compressed to a higher total pressure and expelled in a circumferential and a radial direction through the outlet 68. In some forms a diffuser is situated to receive the compressed fluid exiting through the outlet 68. The diffuser can take any variety of form, and is usually sized to provide minimal gap and minimal step from the hub and shroud to the diffuser.
The impeller 56 includes a central bore 70 into which can be inserted any variety of useful mechanisms to connect the impeller 56 to a driven shaft of the centrifugal compressor 52. Such connections can include a threaded rod, a shaft that captures the impeller 56 through use of a connection, etc. No limitation is hereby intended of the connection type between impeller 56 and suitable prime mover (electric, internal combustion engine, etc) used to drive the impeller 56. Though the bore 70 is shown as being formed to fully extend between the front side 58 and back side 60, in some forms the bore 70 may only extend partially between the two, with an open end at either the front side 58 or back side 60. The back side 60 includes a flat, planar backwall 72 that extends between the bore 70 and a tip 74.
Turning now to
In some embodiments the convex inner part 78 and/or concave outer part 80 are defined by curves. Such curves can be a single radius curve that extends over the length of the inner part 78 and/or outer part 80, but in other forms the convex inner part 78 and/or concave outer part 80 are defined by compound curves. In still other forms the inner part 78 and/or outer part 80 can be defined by a Bezier spline. In some forms a radius of curvature of the inner part 78 at the transition 84 can be the same radius of curvature of the outer part 80 at the transition 84, but in other forms the radii can be different. In one nonlimiting form the radius of curvature of the inner part 78 at the transition 84 is smaller than the radius of curvature of the outer part 80 at the transition 84, but other embodiments may include a higher radius of curvature of the inner part at the transition 84 than the radius of curvature of the outer part 80 at the transition 84. As will be appreciated given the description herein, in some forms the transition 84 can be an inflection point denoting a change in the direction of curvature. The inflection point can in some forms denote a discontinuous change in the direction of curvature, but other forms can denote a continuous change in the direction of curvature. As will be appreciated, many of the shapes contemplated herein can be considered to result in an S-shaped backwall 72.
Other features can be present on either embodiment of
It will be appreciated in this technical area that the centrifugal impeller is a body of revolution, and as such when discussing the “flat,” “planar,” “convex,” “concave,” “nonlinear,” “curved,” etc features of any particular part (e.g. in the illustrations the reference lines are grouped to one side) that the features are circumferentially distributed in the impeller by nature of its body of revolution.
One aspect of the present disclosure includes an apparatus comprising a centrifugal impeller having a blade side and a backwall side, the backwall side having a backwall and a hub region configured with a bore to be affixed to a rotatable shaft, the blade side including a plurality of impeller blades that extend from a first axial end to a first radial end of the centrifugal impeller, the plurality of impeller blades configured to receive a working fluid in the first axial end, compress the working, and discharge the working fluid through the first radial end when the centrifugal impeller is being operated, the backwall of the centrifugal impeller defined by: a flat area that extends inward from an outermost radial extent of the centrifugal impeller to a first location; a flat area in the hub region that extends outward from an outer diameter of the bore to a second location; and a compound curve located between the first location and the second location.
A feature of the present disclosure includes wherein the compound curve is a curve having first radius of curvature in a radial inward region of the compound curve, and a curve having a second radius of curvature in a region radial outward of the radial inward region.
Another feature of the present disclosure includes wherein the compound curve is a convex curve at the first radius of curvature, and a concave curve at the second radius of curvature.
Yet another feature of the present disclosure includes wherein the compound curve includes an inflection point between a radial inward region of the compound curve and a radial outward region of the compound curve, the inflection point denoting a change in direction of the compound curve.
Still another feature of the present disclosure includes wherein the inflection point occurs at a location greater than 50% of the distance from a rotational axis of the centrifugal impeller to the outermost radial extent of the centrifugal impeller.
Yet still another feature of the present disclosure includes wherein the inflection point also marks a discontinuity between a radius of curvature of backwall as it transitions from the radial inward region to the radial outward region.
Still yet another feature of the present disclosure includes wherein the compound curve provides a lower bore stress, lower tip deflection, and lower out of reference plane deflection than an impeller with identical geometry and mass properties but with a flat backwall instead of a compound curve.
A further feature of the present disclosure includes wherein the centrifugal impeller includes an inducer at the first axial end and an exducer at the first radial end, and wherein the compound curve is a convex curve.
A still further feature of the present disclosure includes wherein the compound curve includes a concave curve at a location radially outward of the convex curve.
Another aspect of the present disclosure includes an apparatus comprising a centrifugal impeller having a plurality of blades on a first side and a backwall on a second side, the centrifugal impeller including an intake on a first axial end of the first side and an outlet on an outer radial end of the first side, the centrifugal impeller having a bore hole and a bore hole flat area on the back side surrounding the bore hole, the backwall also defined by a tip region flat area near the outer radial end, the backwall including a convex region defined by an outward projection of material located between the bore hole flat area and the tip region flat area.
A feature of the present disclosure includes wherein the centrifugal impeller also includes a concave region located radially outward of the convex region.
Another feature of the present disclosure includes wherein at least one of the concave region and convex region is defined by a compound curve.
Still another feature of the present disclosure includes wherein the convex region and concave region have different radius of curvatures proximate an inflection point that denotes the transition between the convex region and the concave region.
Yet another feature of the present disclosure includes wherein the inflection point is located at least 50% of the distance between an axis of rotation of the centrifugal impeller and a tip at the tip region flat area of the centrifugal impeller.
Still yet another feature of the present disclosure includes wherein at least one of the bore hole flat area and tip region flat area is planar.
Yet still another feature of the present disclosure includes wherein the centrifugal impeller also includes a concave region located radially outward of the convex region, and which further includes an inflection point denoting the transition between the convex region and concave region that is located at least 50% of the distance between an axis of rotation of the centrifugal impeller and a tip at the tip region flat area of the centrifugal impeller.
A further feature of the present disclosure includes wherein at least one of the convex region and concave region is a compound curve.
A still further feature of the present disclosure includes wherein the compound curve provides a lower bore stress, lower tip deflection, and lower out of reference plane deflection than an impeller with identical geometry and mass properties but with a flat backwall instead of a compound curve.
Yet another aspect of the present disclosure includes an apparatus comprising a centrifugal compressor impeller having a plurality of blades disposed on a front side and a backwall disposed on a back side, the backwall having a central flat area surrounding a bore of the centrifugal compressor impeller and a convex shape extending from the central flat area toward a tip of the centrifugal compressor impeller.
A feature of the present disclosure includes wherein the centrifugal compressor impeller also includes a flat area at the tip of the centrifugal compressor impeller.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
