Impeller with variable sweepback angle

Abstract

An impeller for a flow device is described herein. The impeller includes a hub and a plurality of blades extending radially outward from the hub, where each of the blades is at least partially attached to an outer surface of the hub such that at least a portion of a tip end of the corresponding blade opposite the hub remains unattached to the outer surface of the hub, where the unattached portion of the blade is free to deflect based on a rotational speed of the impeller, and where the blade is free to deflect based on the rotational speed of the impeller. And the sweepback angle of the corresponding blade is correspondingly adjusted within a predefined range.

Description

Technical Field

[0001] The present invention relates to the field of impellers, and more particularly to impellers having a variable sweep angle. Summary of the Invention

[0002] An impeller for a flow device is described herein. The impeller includes a hub and a plurality of blades extending radially outward from the hub, wherein each of the blades is at least partially attached to an outer surface of the hub such that at least a portion of a distal end portion of the corresponding blade opposite the hub remains unattached to the outer surface of the hub, wherein the unattached portion of the blade is freely deflectable based on a rotational speed of the impeller and a sweep angle of the corresponding blade is correspondingly adjusted within a predefined range.

[0003] In one or more embodiments, the unattached portion of the blade extends at least partially beyond the outermost diameter of the hub.

[0004] In one or more embodiments, the predefined range of the sweep angle is in the range of 15 degrees to 60 degrees from the radial direction of the hub.

[0005] In one or more embodiments, each of the blades has a substantially curved profile extending in a predefined direction about a longitudinal axis or rotational axis of the hub such that a plurality of fluid passages are formed or defined between adjacent blades to allow fluid to flow therethrough.

[0006] In one or more embodiments, the outer surface of the hub has a substantially curved profile, wherein the outer diameter of the hub increases in a certain direction while moving from the front end of the hub toward the rear end of the hub, wherein the unattached portion of the hub extends at least partially beyond the outer diameter of the rear end of the hub.

[0007] In one or more embodiments, each of the blades includes a coupling side attached to an outer surface of the hub, a leading edge located near the leading end of the hub, a trailing edge located near the trailing end of the hub, and a curved edge opposite the coupling side and extending between the trailing edge and the leading edge of the corresponding blade.

[0008] In one or more embodiments, the trailing edges of the plurality of blades are circumferentially offset from the corresponding leading edges of the blades.

[0009] In one or more embodiments, a portion of each of the blades at the leading edge is substantially curved in a direction opposite to the predefined direction.

[0010] In one or more embodiments, each of the blades has a variable thickness between the leading edge and the trailing edge of the corresponding blade.

[0011] In one or more embodiments, the thickness of each of the blades decreases while moving in a radial direction from the coupling side toward the tip end or outer edge of the corresponding blade.

[0012] In one or more embodiments, each of the blades has a variable thickness between the coupling side and the curved edge of the corresponding blade.

[0013] In one or more embodiments, the thickness of each of the blades decreases while moving in a direction from a leading edge of the corresponding blade toward a trailing edge of the corresponding blade.

[0014] In one or more embodiments, the thickness of each of the blades increases while moving from a leading edge of the corresponding blade toward a middle portion of the corresponding blade, and further decreases while moving toward a trailing edge of the corresponding blade.

[0015] In one or more embodiments, the impeller includes a shroud surrounding the hub and the plurality of blades such that a first end of the shroud located near the leading edge of the blades remains open to allow fluid to flow in the first end, and a second end of the shroud located near the trailing edge of the blades remains open to allow fluid to flow out of the second end.

[0016] In one or more embodiments, the shroud surrounds the hub and the plurality of blades such that unattached portions of the blades remain enclosed by the shroud and unattached to the shroud.

[0017] In one or more embodiments, the shroud has a substantially curved profile, wherein the diameter of the shroud In The amount of the hub increases as it moves from the front end portion of the hub toward the rear end portion of the hub.

[0018] In one or more embodiments, the plurality of blades, the hub, and the shroud are made of a non-metallic material.

[0019] In one or more embodiments, the plurality of blades are made of a composite material having a predetermined flexural modulus.

[0020] In one or more embodiments, the impeller includes a plurality of flow splitters configured to be arranged alternately with the plurality of blades such that one of the flow splitters remains between adjacent blades, wherein the flow splitters extend radially outward from the hub such that at least a portion of a terminal end portion of a corresponding flow splitter opposite the hub remains unattached to the outer surface of the hub.

[0021] In one or more embodiments, the flow device is selected from the group consisting of a centrifugal compressor, a centrifugal pump, and a turbine.

[0022] The foregoing summary is illustrative only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, features, and techniques of the subject disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of the subject disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the subject disclosure and together with the description serve to explain the principles of the subject disclosure.

[0024] In the drawings, similar components and / or features may have the same reference number. In addition, various components of the same type may be distinguished by following the reference number with a second reference number that distinguishes between the similar components. If only the first reference number is used in the specification, the description applies to any of the similar components having the same first reference number, regardless of the second reference number.

[0025] Figures 1A to 1C An exemplary view illustrating an unshrouded impeller for a flow device (centrifugal compressor) according to one or more embodiments of the subject disclosure is shown.

[0026] Figures 2A to 2C An exemplary view illustrating a shrouded impeller for a flow device (centrifugal compressor) according to one or more embodiments of the subject disclosure is shown.

[0027] Figure 3A and Figure 3B An exemplary top view representation of an impeller according to one or more embodiments of the subject disclosure is illustrated to depict the variation in sweep angle at different rotational speeds. DETAILED DESCRIPTION

[0028] The following is a detailed description of an embodiment of the subject disclosure, as depicted in the accompanying drawings. The embodiment is detailed enough to clearly convey the subject disclosure. However, the amount of detail provided is not intended to limit the intended variations of the embodiment; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject disclosure as defined by the appended claims.

[0029] Various terms are used herein. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.

[0030] As used herein, the term "front end" refers to the upstream end of the impeller that first receives or contacts the fluid flowing through the flow device, whether the flow device is a compressor, a pump, or a turbine. Additionally, as used herein, the term "rear end" refers to the downstream end of the impeller, opposite the upstream end.

[0031] As used herein, the terms "longitudinal axis" and "axis of rotation" refer to the z-axis about which the impeller in a flow device rotates, regardless of whether the flow device is a compressor, pump, or turbine. Additionally, as used herein, the term "radial direction" refers to an axis perpendicular to the z-axis.

[0032] In the specification, reference may be made to the spatial relationships between various components, as well as the spatial orientation of various aspects of the components of the device as depicted in the accompanying drawings. However, as will be appreciated by those skilled in the art after reading this subject disclosure in its entirety, the components of the invention described herein may be positioned in any desired orientation. Therefore, the use of terms such as "above," "below," "upper," "lower," "first," "second," or other similar terms to describe the spatial relationships between various components or to describe the spatial orientation of aspects of such components should be understood to describe the relative relationships between the components described herein or the spatial orientation of aspects of such components, respectively, which may be oriented in any desired direction.

[0033] Flow devices, such as, but not limited to, centrifugal compressors, play an important role in a wide range of applications, such as HVAC systems. The efficiency, performance, and operational flexibility of these compressors can be significantly affected by the design of their impellers, particularly the geometry of the impeller blades. The sweep angle of the impeller blades is an important design parameter that can affect the performance characteristics of a centrifugal compressor. This sweep angle, defined by the orientation of the blade's trailing edge relative to the direction of rotation, can affect the compressor's operating range, efficiency, and the head it can generate.

[0034] Typically, an impeller with a larger sweep angle can have a wider operating range, but may sacrifice some head, making it suitable for applications that require varying flow conditions. Conversely, an impeller with a smaller sweep angle can produce a higher head, which is beneficial for applications where a significant increase in pressure is required at a relatively constant flow rate.

[0035] The operating point of chillers and heat pumps (HP), important components in cooling and heating systems, respectively, can often necessitate specific performance characteristics for the centrifugal compressors they employ. Adjusting the sweep angle of the impeller blades can optimize the compressor's performance to match the desired operating point, thereby enhancing the system's overall efficiency and effectiveness.

[0036] However, conventional impeller designs (whether shrouded or unshrouded) have a fixed sweep angle. These blades, which stretch from leading edge to trailing edge, are rigidly attached to the hub (and, in the case of shrouded impellers, to the shroud). As a result, once manufactured, the sweep angle of these impellers cannot be adjusted to meet changing operating requirements or optimize performance over a wide range of conditions. This inherent inflexibility can limit the adaptability of centrifugal compressors, compromising efficiency or operating range (which depends on the fixed geometry of the impeller blades).

[0037] Therefore, a solution is needed that effectively addresses the challenges associated with existing impellers used in flow devices (centrifugal compressors) by providing an improved impeller that can adjust its sweep angle in response to changing operational requirements. This can improve the overall performance and operating range of flow devices equipped with such impellers.

[0038] refer to Figures 1A to 2C , discloses an impeller 100 for use with a flow device associated with a heating, ventilation, and air conditioning (HVAC) system (not shown). In one or more embodiments, the flow device can be selected from the group consisting of, but not limited to, a centrifugal compressor, a centrifugal pump, and a turbine. Although various embodiments have been described herein with respect to the flow device being a centrifugal compressor for the sake of brevity, the impeller can also be associated with other flow devices without limitation.

[0039] In one or more embodiments, the impeller 100 may include a hub 102 having an outer surface 102A extending from a front end 102-1 (upstream end 102-1) of the hub 102 toward a rear end 102-2 (downstream end 102-2) of the hub 102 (along a flow path of a fluid in the flow device). The hub 102 may also include an inner diameter surface 102-B at one end that may be configured to receive and mate with a shaft of a drive (motor and / or gear) (not shown) associated with the flow device, such that rotation of the drive may cause the hub 102 and the impeller 100 to rotate within the flow device about a longitudinal axis or rotational axis AA' of the hub 102.

[0040] The impeller 100 may further include a plurality of blades 104 (also referred to herein as main blades 104) extending radially outward from an outer surface 102A of the hub 102. In one or more embodiments, each of the blades 104 may have a substantially curved profile that extends outward from the hub 102 and curves in a predefined (clockwise or counterclockwise) direction about the longitudinal axis or rotational axis AA' of the hub 102, such that a plurality of fluid passages 106 are formed or defined between adjacent blades 104 to allow fluid to flow therethrough. However, in other embodiments, the blades 104 may also have a substantially straight profile without limitation.

[0041] As illustrated, each of the blades 104 may include a leading edge 104A located near the leading end 102-1 of the hub 102, a trailing edge 104B located near the trailing end 102-2 of the hub 102, a coupling side extending between the trailing edge 104B and the leading edge 104A that remains attached to the outer surface 102A of the hub 102, a curved edge 104C extending between the trailing edge 104B and the leading edge 104A of the corresponding blade 104 opposite the coupling side, and a tip T defining the trailing edge 104B. The blade 104 may thus define a first face 104D (surface) and a second face 104E (opposite the first face) between the leading edge 104A, the trailing edge 104B, the coupling side, and the curved edge 104C.

[0042] In one or more embodiments, each of the blades 104 may be at least partially attached to the outer surface 102A of the hub 102 such that at least a portion or length (L) of the tip end or trailing edge 104B end of the corresponding blade 104 remains unattached to the outer surface 102A of the hub 102. Furthermore, the unattached portion L of the blade 104 may at least partially extend beyond the outermost diameter of the hub 102 (the outer periphery of the trailing end 102-2). Thus, the unattached portion L of the blade 104 may be free to deflect based on the rotational speed of the impeller 100, and the sweep angle (β) of the corresponding blade 104 may be correspondingly adjusted within a predefined range, such as Figure 3A and 3B As shown in .

[0043] In one or more embodiments, each of the blades 104 may have a variable thickness between the coupling side and the curved edge 104C of the corresponding blade 104. However, in other embodiments, each of the blades 104 may have a uniform thickness between the coupling side and the curved edge 104C of the corresponding blade 104. Furthermore, in one or more embodiments, each of the blades 104 may have a variable thickness between the leading edge 104A and the trailing edge 104B of the corresponding blade 104. However, in other embodiments, each of the blades 104 may have a uniform thickness between the leading edge 104A and the trailing edge 104B of the corresponding blade 104.

[0044] Additionally, in one or more embodiments, but not limited thereto, the width of each of the blades 104 may also decrease while moving from the leading edge 104A of the corresponding blade 104 toward the trailing edge 104B of the corresponding blade 104. However, in other embodiments, the width of each of the blades 104 may also be the same, or may increase while moving between the leading edge 104A and the trailing edge 104B of the corresponding blade 104.

[0045] In one or more embodiments, but not limited thereto, the thickness of each of the blades 104 may decrease while moving in a radial direction from the coupling side toward the distal end or outer edge of the corresponding blade 104. Furthermore, in one or more embodiments, the thickness of each of the blades 104 may increase while moving in a direction from the leading edge 104A of the corresponding blade 104 toward the trailing edge 104B of the corresponding blade 104. Furthermore, in some embodiments, the thickness of each of the blades 104 may first increase while moving from the leading edge 104A of the corresponding blade 104 toward the middle portion of the corresponding blade 104, and further decrease while moving toward the trailing edge 104B of the corresponding blade 104. However, in other embodiments, the thickness of each of the blades 104 may decrease while moving from the leading edge 104A of the corresponding blade 104 toward the trailing edge 104B of the corresponding blade 104.

[0046] In one or more embodiments, Figure 3A As shown in FIG, when the impeller 100 rotates at a lower rotational speed, the centrifugal force on the tip end or trailing edge 104B of the blade 104 may be smaller. This reduction in centrifugal force may result in less deflection in the blades 104 of the impeller 100, thereby maintaining a high sweep angle (β). In addition, in one or more embodiments, as shown in FIG. Figure 3A As shown in , when the impeller 100 rotates at a higher rotational speed, the increased centrifugal force may cause the blades 104 of the impeller 100 to straighten, thereby causing the sweep angle (β') to decrease. In one or more embodiments, the variable sweep angle (β) to (β') design of the impeller 100 may allow it to operate at rotational speeds within a range of 60% to 105% of the design (nominal) speed. Therefore, the sweep angle (β) of the blades 104 of the impeller 100 may vary within a predefined range of 15 to 60 degrees in the radial direction from the hub 102. Therefore, such variation in the sweep angle (β) in the blades 104 of the impeller 100 may improve the overall performance and operating range of the associated centrifugal compressor and HVAC system.

[0047] In one or more embodiments, the outer surface 102A of the hub 102 may extend axially at the forward (upstream) end and then extend radially outward at the aft (downstream) end such that an axial inlet to the longitudinal axis AA' may be formed at the forward end 102-1 and a radial outlet may be formed at the aft end 102-2 of the hub 102, in a housing (not shown) or shroud (not shown) associated with the flow device. Figures 2A to 2CAs a result, the outer surface 102A of the hub 102 may have a substantially curved profile, wherein the outer diameter of the hub 102 may increase in a certain direction while moving from the front end 102-1 of the hub 102 toward the rear end 102-2 of the hub 102. However, in other embodiments, the hub 102 may also have a cylindrical profile.

[0048] In one or more embodiments, a portion of the blade 104 proximate the leading end 102-1 may project generally radially outward from the hub 102, and another portion toward the trailing end 102-2 may project axially from the hub 102. In one or more embodiments, the trailing edge 104B of the blade 104 may be circumferentially offset from the corresponding leading edge 104A of the blade 104. Furthermore, a portion of each blade 104 at the leading edge 104A may be substantially curved in a direction opposite to the predefined direction. Thus, a portion of the blade 104 proximate the trailing end 102-2 may remain generally axially oriented relative to the radial outlet of the impeller 100. However, a portion of the blade 104 proximate the leading edge 104A may remain generally radially oriented or substantially parallel to the plane of the axial inlet of the impeller 100 (perpendicular to the axis of rotation AA').

[0049] In one or more embodiments, the impeller 100 may include a plurality of flow splitters 108 (also referred to herein as flow splitter blades or secondary blades) configured to be arranged in an alternating arrangement with the plurality of main blades 104 such that one of the flow splitters 108 is maintained between adjacent main blades 104. The flow splitters 108 may be configured to separate fluid flowing through the fluid passages 106 formed between adjacent blades 104. The flow splitters 108 may also have a substantially curved profile that may extend radially outward from the hub 102 and remain attached to the outer surface 102A of the hub 102. Furthermore, the length of the flow splitters 108 may be substantially less than that of the main blades 104 such that the trailing edge of the flow splitters 108 may be free to deflect and may also extend beyond the outer diameter of the hub 102. However, in one or more embodiments (not shown), the length of the flow splitters 108 may be substantially less than that of the main blades 104, wherein the flow splitters 108 do not extend beyond the outer diameter of the hub 102.

[0050] refer to Figures 2A to 2CIn one or more embodiments, the impeller 100 may include a shroud 110 that surrounds the hub 102, blades 104, and flow splitter 108, such that a first end 110-1 of the shroud 110, or the front end 102-1 of the impeller 100, located near the leading edge 104A of the blades 104, remains open to form an axial inlet 110A that allows fluid to flow therein. Furthermore, a second end 110-2 of the shroud 110, or the rear end 102-2 of the impeller 100, located near the trailing edge 104B of the blades 104, remains open to form a radial outlet 110B that allows fluid to flow therefrom. Furthermore, the shroud 110 may surround the hub 102 and blades 104 such that an unattached portion L of the blades 104 remains enclosed by the shroud 110 and is unattached thereto. Furthermore, the unattached portion L of the blades 104 may at least partially extend out of the shroud 110 via the radial outlet.

[0051] In one or more embodiments, the shroud 110 may also have a substantially curved profile based on the outer profile of the hub 102 and the blades 104. The diameter of the shroud 110 may increase while moving from the first end 110-1 of the shroud 110 toward the second end 110-2 of the shroud 110, or from the front end 102-1 of the hub 102 toward the rear end 102-2 of the hub 102. As illustrated, the axial inlet 110A of the shroud 110 or impeller 100 may have an opening of a predefined diameter extending along a plane perpendicular to the longitudinal axis AA' at the front end 102-1. Additionally, the radial outlet 110B of the shroud 110 or impeller 100 may have an opening of a predefined width that remains axially oriented and extends circumferentially around the outer diameter of the rear end 102-2 of the hub 102.

[0052] In one or more embodiments, Figures 2A to 2C In the shrouded impeller 100 shown in FIG, an integral shroud 110 may surround the blades 104 so that the blades 104 extend across the flow path between the surface of the hub 102 and the surface of the shroud 110. The shroud 110 may stiffen the blades 104 and reduce vibration. This may allow for the use of relatively thinner blade structures than in an equivalent open impeller 100 in which the blades 104 are secured only to the hub 102. Additionally, in one or more embodiments, in the embodiment shown in FIG. Figures 1A to 1C In the open impeller 100 design shown in FIG (without the shroud 110), the edges of the blades 104 may closely interface with a separate casing on the compressor. There may be position control between the impeller 100 and the casing to balance the efficiency loss due to leakage with the risk of damage from the impeller contacting the casing.

[0053] refer to Figures 1A to 2CIn one or more embodiments, the blades 104, hub 102, splitter 108, and shroud 110 of the impeller 100 may be made of non-metallic, non-corrosive materials. Additionally, the blades 104, hub 102, splitter 108, and shroud 110 of the impeller 100 may be made of an alloy. However, in other embodiments, the flow device and impeller 100 may be constructed using any standard or newly developed materials and methods, and all such embodiments are within the scope of the present subject disclosure. In one or more embodiments, the impeller 100 or components of the impeller 100 may be manufactured using an additive manufacturing process and / or 3D printing technology. However, the impeller 100 or components thereof may also be manufactured using any standard or newly developed methods, and all such embodiments are within the scope of the present subject disclosure.

[0054] Furthermore, in one or more embodiments, the plurality of blades 104 may be made of a composite material having a predetermined flexural modulus, which may be coated with a layer(s) of a non-corrosive material(s). This may provide the blades 104 with inherent flexibility, allowing them to deflect and adjust their sweep angle based on the rotational speed of the impeller 100.

[0055] Thus, the present invention overcomes the challenges associated with existing impellers by providing an improved impeller that is capable of adjusting its sweep angle in response to varying operating speeds without the need for any external control mechanism. It will be appreciated that when the compressor (flow device) is operated at lower rotational speeds typical of part-load conditions in an HVAC system (refrigerator or heat pump), the centrifugal forces are lower. This reduction in force results in less deflection in the blades of the impeller, thereby maintaining a high sweep angle. Furthermore, when the compressor is operated at higher rotational speeds typical during full-load conditions in an HVAC system (refrigerator or heat pump), the increased centrifugal forces cause the blades of the impeller to straighten, resulting in a reduction in the sweep angle. This improves the overall performance and operating range of the associated centrifugal compressor and HVAC system.

[0056] Although the subject disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the subject disclosure as defined by the appended claims. Modifications may be made to adapt a particular situation or material to the teachings of the subject disclosure without departing from the scope of the subject disclosure. Therefore, it is intended that the subject disclosure is not limited to the particular embodiments disclosed, but that the subject disclosure includes all embodiments falling within the scope of the subject disclosure as defined by the appended claims.

[0057] In interpreting this specification, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "comprise" and "include" should be interpreted as referring to elements, parts, or steps in a non-exclusive manner, indicating that the referenced elements, parts, or steps may be present, utilized, or combined with other elements, parts, or steps not explicitly referenced. In the event that the specification claims refer to at least one element selected from the group consisting of A, B, C, ..., and N, the text should be interpreted as requiring only one element from that group, rather than A plus N or B plus N, etc.

Claims

1. An impeller for a flow device, the impeller comprising: hub; as well as a plurality of blades extending radially outward from the hub, wherein each of the blades is at least partially attached to an outer surface of the hub such that at least a portion of a terminal end portion of the corresponding blade opposite the hub remains unattached to the outer surface of the hub, The unattached portion of the blade is freely deflectable based on the rotation speed of the impeller, and the sweep angle of the corresponding blade is correspondingly adjusted within a predefined range.

2. The impeller according to claim 1, wherein: The unattached portion of the blade extends at least partially beyond an outermost diameter of the hub.

3. The impeller according to any one of claims 1 and 2, wherein: The predefined range of the sweep angle is within a range of 15 degrees to 60 degrees from a radial direction of the hub.

4. The impeller according to any one of claims 1 to 3, wherein: Each of the blades has a substantially curved profile extending in a predefined direction about a longitudinal axis or rotational axis of the hub such that a plurality of fluid passages are formed or defined between adjacent blades to allow fluid to flow therethrough.

5. The impeller according to any one of claims 1 to 4, wherein: The outer surface of the hub has a substantially curved profile, wherein the outer diameter of the hub increases in a certain direction while moving from the front end of the hub toward the rear end of the hub, wherein the unattached portion of the hub at least partially extends beyond the outer diameter of the rear end of the hub.

6. The impeller according to any one of claims 1 to 5, wherein: Each of the blades includes a coupling side attached to the outer surface of the hub, a leading edge located near the leading end of the hub, a trailing edge located near the trailing end of the hub, and a curved edge opposite the coupling side and extending between the trailing edge and the leading edge of the corresponding blade.

7. The impeller according to any one of claims 1 to 6, wherein: The trailing edges of the plurality of blades are circumferentially offset from the corresponding leading edges of the blades.

8. The impeller according to any one of claims 1 to 7, wherein: A portion of each of the blades at the leading edge is substantially curved in a direction opposite to the predefined direction.

9. The impeller according to any one of claims 1 to 8, wherein: Each of the blades has a variable thickness between the leading edge and the trailing edge of the corresponding blade.

10. The impeller according to claim 9, wherein: The thickness of each of the blades decreases while moving in a radial direction from the coupling side toward the tip end or outer edge of the corresponding blade.

11. The impeller according to any one of claims 1 to 10, wherein: Each of the blades has a variable thickness between the coupling side and the curved edge of the corresponding blade.

12. The impeller according to claim 11, wherein: The thickness of each of the blades decreases while moving in a direction from the leading edge of the corresponding blade toward the trailing edge of the corresponding blade.

13. The impeller according to claim 11, wherein: The thickness of each of the blades increases while moving from the leading edge of the corresponding blade toward a middle portion of the corresponding blade, and further decreases while moving toward the trailing edge of the corresponding blade.

14. The impeller according to any one of claims 1 to 13, wherein: The impeller includes a shroud surrounding the hub and the plurality of blades such that a first end of the shroud located near the leading edge of the blade remains open to allow fluid to flow in the first end, and a second end of the shroud located near the trailing edge of the blade remains open to allow the fluid to flow out of the second end.

15. The impeller according to claim 14, wherein: The shroud surrounds the hub and the plurality of blades such that the unattached portions of the blades remain enclosed by the shroud and unattached to the shroud.

16. The impeller according to any one of claims 14 and 15, wherein: The shroud has a substantially curved profile, wherein a diameter of the shroud increases while moving in a direction from a front end portion of the hub toward a rear end portion of the hub.

17. The impeller according to any one of claims 1 to 16, wherein: The plurality of blades, the hub, and the shroud are made of a non-metallic material.

18. An impeller according to any one of claims 1 to 17, wherein: The plurality of blades are made of a composite material having a predetermined flexural modulus.

19. The impeller according to any one of claims 1 to 18, wherein: The impeller includes a plurality of flow splitters configured to be arranged alternately with the plurality of blades such that one of the flow splitters is retained between adjacent blades, wherein the flow splitters extend radially outward from the hub such that at least a portion of a terminal end portion of a corresponding flow splitter opposite to the hub remains unattached to the outer surface of the hub.

20. An impeller according to any one of claims 1 to 19, wherein The flow device is selected from the group consisting of a centrifugal compressor, a centrifugal pump, and a turbine.

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