Hydraulic turbine

Abstract

A hydraulic turbine impeller includes a hub and a plurality of pivotable blades extending from the hub. Each of the plurality of pivotable blades includes a root located on the hub, a tip opposite the root, and a leading edge. Each of the plurality of pivotable blades is pivotable relative to the hub about its respective pivot axis. For at least one blade, the leading edge at the root is positioned along the radial axis of the impeller, and the leading edge at the tip is cantilevered across the radial axis in the circumferential direction of the impeller.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims the interests of U.S. Provisional Patent Application No. 63 / 536,266, filed on 1 September 2023, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a hydroelectric turbine impeller. Specifically, the present invention relates to a turbine impeller configured to achieve high efficiency over a wide operating range while simultaneously facilitating the safe downstream passage of fish or other aquatic organisms through the turbine. [Background technology]

[0003] There is a growing need for hydroelectric power plants with minimal environmental impact. To reduce environmental impact, it is desirable that hydroelectric power plants have minimal impact on fish and other aquatic organisms (for example, by not harming aquatic life and not hindering the movement or migration of aquatic organisms). It is also desirable to construct hydroelectric power plants that are highly efficient and have relatively low installation, operation, and maintenance costs. Furthermore, it may be desirable to retrofit existing hydroelectric power plants with new turbines to reduce environmental impact and / or improve efficiency.

[0004] Therefore, in this field of technology, there is a continuing need for turbines that enable the safe downstream passage of fish and other aquatic organisms through the turbine, have high efficiency, relatively low installation, operation, and maintenance costs, and can be used in a wide range of applications, including retrofit installations. [Overview of the project]

[0005] A turbine impeller for a hydraulic turbine may include a hub and a plurality of pivotable blades extending from the hub. Each of the plurality of pivotable blades may include a root located at the hub, a tip opposite the root, and a leading edge. Each of the plurality of pivotable blades may be pivotable relative to the hub about its own pivot axis. Leading edge T LE Impeller D of thickness RThe ratio of the impeller to the diameter may range from approximately 0.03 to approximately 0.35. For at least one blade, the leading edge at the root may be positioned along the radial axis of the impeller, and the leading edge at the tip may be cantilevered beyond the radial axis in the circumferential direction of the impeller. The impeller may include a ratio of impeller shaft length to impeller diameter of less than 0.55. The impeller may include a ratio of chord length at the tip of each pivotable blade to impeller diameter of less than 0.9. The impeller may be configured such that each pivot axis is angled with respect to the impeller shaft axis at an angle between approximately 8 degrees and approximately 155 degrees. The impeller may be configured such that each pivot axis is angled with respect to the impeller shaft axis at an angle between approximately 30 degrees and approximately 100 degrees. The impeller may be configured such that each pivot axis is angled with respect to the impeller shaft axis at an angle between approximately 90 degrees. The outer surface of the hub can be swept by the root of each pivotable blade during the rotation of the blade from maximum pitch to minimum pitch, and can be shaped spherically. The root of each pivotable blade can conform to the shape of the outer surface of the hub during the rotation of the blade from maximum pitch to minimum pitch. The tip of each pivotable blade can have a generally spherical sweep shape over the pivot range of the blade from maximum pitch to minimum pitch. The thickness of the leading edge of each pivotable blade can be about 100 mm to about 700 mm. A portion of the leading edge at the tip of each pivotable blade can be inclined with respect to the radial axis of the impeller at an angle between about 20 degrees and about 90 degrees. A portion of the leading edge at the tip of each pivotable blade can be inclined with respect to the radial axis of the impeller at an angle between about 25 degrees and about 45 degrees. The leading edge of each pivotable blade can be arc-shaped when viewed along an axis perpendicular to the shaft axis of the impeller. When viewed along an axis perpendicular to the impeller shaft, the leading edge of each pivotable blade can curve away from the upstream end of the impeller at its root and then curve back toward the upstream end of the impeller towards its tip. The radius of curvature of one or more faces may be greater than the radius of curvature of the rounded edge of the hub. The first portion of the trailing edge may be concave, the second portion of the trailing edge may be convex, and the first portion of the trailing edge may be positioned closer to the hub than the second portion of the trailing edge.The ratio of the chord length at the tip of each pivotable blade to the chord length at the base of each pivotable blade can be approximately 1.6 to 2.5.

[0006] An impeller can be used within a turbine, and the impeller is located within a housing that defines an inlet and outlet for the flow of fluid. The tip of each pivotable blade can conform to the shape of the housing's discharge ring during the rotation of the blade from maximum pitch to minimum pitch. The inner surface of the housing's discharge ring, swept by the tip of each pivotable blade during the rotation of the blade from maximum pitch to minimum pitch, can be shaped into a spherical form. The housing's discharge ring may have removable segments assembled to be removable from either the outside or inside of the turbine. The housing's discharge ring can be divided axially. The housing's discharge ring can be divided radially. The turbine may include a generator operably coupled to the impeller, such as a fixed-speed generator or a variable-speed generator.

[0007] Some embodiments of the hydraulic turbine impeller described herein may include a hub and a plurality of pivotable blades extending from the hub. Each of the plurality of pivotable blades may include a root located on the hub, a tip opposite the root, and a front end opposite the rear end. Each of the plurality of pivotable blades may be pivotable relative to the hub about its respective pivot axis. For at least one blade, the leading edge at the root may be positioned along the radial axis of the impeller, and the leading edge at the tip may be cantilevered across the radial axis in the circumferential direction of the impeller. Thickness T of the leading edge LE The diameter of the impeller D R The ratio to is in the range of approximately 0.03 to approximately 0.35. The thickness of the leading edge can be greater than the thickness of the trailing edge. In the meridian section, the trailing edge at the root of the blade can be located further downstream than the trailing edge at the tip of the blade.

[0008] In any of the various embodiments described herein, the trailing edge can extend behind the downstream end of the hub for at least one of the plurality of pivotable blades. In some examples, at least one of the plurality of pivotable blades has a cross-section with a surface curvature having a first shape and a second shape at the root, the first shape being concave and the second shape being convex.

[0009] In any of the various embodiments described herein, the hub can include a plurality of faces that can be planar, and the plurality of faces are radially spaced around the longitudinal axis of the hub. In some embodiments, the trailing edge of one of the plurality of pivotable blades can be arcuate upstream between the tip and the root of the pivotable blade.

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the present disclosure and, together with the description of the specification, further serve to explain the principles and to enable one of ordinary skill in the art to make and use it.

Brief Description of the Drawings

[0011] [Figure 1] A perspective view of an impeller for a hydraulic turbine according to an embodiment. [Figure 2] Another perspective view of the impeller of FIG. 1. [Figure 3] Another perspective view of the impeller of FIG. 1. [Figure 4] An upstream view of the impeller of FIG. 1. [Figure 5] A downstream view of the impeller of FIG. 1. [Figure 6] A side view of the impeller of FIG. 1. [Figure 7] Another side view of the impeller of FIG. 1. [Figure 8] Another side view of the impeller of FIG. 1. [Figure 9] Another side view of the impeller of FIG. 1. [Figure 10]This is a cross-sectional view of the impeller in Figure 1, taken along the line X-X' in Figure 6. [Figure 11] Another side view of the impeller in Figure 1, which has blades adjusted to a 5-degree angle. [Figure 12] Another side view of the impeller in Figure 1, which has blades adjusted to a 10-degree angle. [Figure 13] Another side view of the impeller in Figure 1, which has blades adjusted to a 17-degree angle. [Figure 14] Figure 1 shows an impeller installed in a hydraulic turbine according to one embodiment, having blades adjusted to a 5-degree angle. [Figure 15] Figure 1 shows an impeller installed in a hydraulic turbine according to one embodiment, which has blades adjusted to a 10-degree angle. [Figure 16] Figure 1 shows an impeller installed in a hydraulic turbine according to one embodiment, having blades adjusted to a 17-degree angle. [Figure 17] This shows an impeller installed in a hydraulic turbine according to one embodiment. [Figure 18] An impeller for a hydraulic turbine according to one embodiment is shown. [Figure 19] An impeller for a hydraulic turbine according to one embodiment is shown. [Figure 20] This is a partial cross-sectional view of a hydraulic turbine impeller according to one embodiment. [Figure 21] This is a top view of a hydraulic turbine impeller according to one embodiment. [Figure 22] This is a perspective view of a hydraulic turbine impeller according to one embodiment. [Figure 22A] This is a perspective view of a hydraulic turbine impeller according to one embodiment having a segmented surface discharge ring. [Figure 23] This shows a side view of a hydraulic turbine impeller according to one embodiment, which has blades adjusted toward the closed position. [Figure 24] This shows a side view of a hydraulic turbine impeller according to one embodiment, which has blades adjusted toward the open position. [Figure 25A]This shows a side view of a hydraulic turbine impeller according to one embodiment, which has blades adjusted toward the open position. [Figure 25B] Figure 25A shows cross-sections of the blade taken at the base, middle span, and tip of the blade. [Figure 26] This shows a rearward perspective view of a hydraulic turbine impeller according to one embodiment, which has blades adjusted toward the closed position. [Figure 27] A perspective view of a hydraulic turbine impeller according to one embodiment is shown. [Figure 28] A graph comparing the normalized chord distribution of a conventional blade and the blade of this disclosure is shown. [Modes for carrying out the invention]

[0012] In the embodiments for carrying out the following inventions, many specific details are given in order to provide a complete understanding of the embodiments of this disclosure. However, it will also be apparent to those skilled in the art that embodiments, including structures, systems, and methods, can be practiced without such specific details. The descriptions and expressions herein are common means used by those skilled in the art to communicate their work to others skilled in the art in the most effective way. In other examples, well-known methods, procedures, components, and circuits are not described in detail in order to avoid unnecessarily obscuring the aspects of the disclosure.

[0013] References to "one embodiment," "an embodiment," "an exemplary embodiment," etc., indicate that the described embodiment(s) may include certain features, structures, or characteristics, but not all embodiments necessarily include those features, structures, or characteristics. Furthermore, such wording does not necessarily refer to the same embodiment. Moreover, when certain features, structures, or characteristics are described in relation to an embodiment, achieving such features, structures, or characteristics in relation to other embodiments is considered to be within the knowledge of those skilled in the art, whether explicitly stated or not.

[0014] As used herein, the terms “about” or “approximately” may mean a range of + / - 5% of the stated quantity or value.

[0015] The following examples are illustrative and not limiting of the disclosure. Other suitable modifications and adaptations of various conditions and parameters are generally accepted in the art and will be apparent to those skilled in the art as being within the spirit and scope of the disclosure.

[0016] Modern hydroelectric power plants often have to meet stringent standards for environmental sustainability. Hydroelectric plants operating with heads of approximately 60 meters or less often disrupt natural ecosystems, particularly by hindering the upstream and downstream movement of fish and other aquatic life. However, the relatively high availability of such installation sites makes hydroelectric development in this range still desirable. Use at medium heads (e.g., heads exceeding 30 meters) is particularly desirable because the power density at these sites is relatively higher compared to low-head sites.

[0017] Several embodiments described herein provide impellers for hydraulic turbines for applications of various sizes, including high-head, medium-head, and low-head applications. Some embodiments include impellers for use in low-head to medium-head applications (e.g., ranging from a head of about 3 meters to about 40 meters), which allow for a safe downstream passage of fish through the turbine incorporating the impeller. Some embodiments described herein also achieve high efficiency and have relatively low costs for installation, operation, and maintenance. Some embodiments described herein also achieve high efficiency over a wide range of flows. Some embodiments described herein can be used in a wide range of applications, including retrofitting, rehabilitation, modernization, and upgrade implementations.

[0018] In some embodiments, the impeller has adjustable pitch blades. This can help achieve high efficiency over a wide range of flow, for example.

[0019] In some embodiments, the pivot axis of the blade is angled relative to the shaft axis of the impeller. An angled pivot axis allows, for example, adjustable pitch blades and simultaneously enables blade features described below (e.g., thick leading edge or cantilevered leading edge). An angled pivot axis can also allow substantially oblique flow through the impeller blade, as seen in delias turbines. In some embodiments, the pivot axis of the blade is selected to minimize the size of the turbine required to accommodate the pivot range of the blade. In one embodiment, the pivot axis of the blade may be perpendicular to the shaft axis.

[0020] In some embodiments, the impeller blades have a thick leading edge relative to the size of the fish that can pass through the turbine. Fish survival after a blade strike event is sensitive to the ratio of the fish's body length to the thickness of the turbine blade leading edge and the speed. For example, a blade with a ratio of fish length to blade thickness < 1 can allow for approximately 100% fish survival after a blade strike at a strike speed of 7 m / s and over 90% at a strike speed of 12 m / s. Consequently, fish that encounter a blade with a thick leading edge are more likely to survive a blade impact compared to fish that encounter a blade with a thinner leading edge.

[0021] In some embodiments, the leading edge of the impeller blade is arc-shaped when viewed along the shaft axis of the impeller. As a result, the orthogonal component w of the strike velocity N= w*sin(a) decreases, which reduces the mortality rate of fish due to impact with the blade.

[0022] In some embodiments, the leading edge of the impeller blade is arc-shaped when viewed along an axis perpendicular to the impeller shaft axis (i.e., from the side of the impeller).

[0023] In some embodiments, the leading edge of the impeller blade is twisted. Such a shape results in an orthogonal component of the strike probability along the entire leading edge wN By minimizing this, it is possible to achieve the maximum possible accumulated fish survival rate along the entire leading edge while simultaneously minimizing the cantilever required by the leading edge tip.

[0024] In some embodiments, the impeller is incorporated into the turbine.

[0025] In some embodiments, the impeller is a Kaplan-type turbine impeller. In some embodiments, the impeller is a Delias-type turbine impeller.

[0026] These and other embodiments will be described in more detail below with reference to the drawings.

[0027] Figures 1 to 13 show impellers 100 according to several embodiments. Figure 1 shows a perspective view of impeller 100, Figure 2 shows another perspective view of impeller 100, Figure 3 shows another perspective view of impeller 100, Figure 4 shows an upstream view of impeller 100, Figure 5 shows a downstream view of impeller 100, Figure 6 shows a side view of impeller 100, Figure 7 shows another side view of impeller 100, Figure 8 shows another side view of impeller 100, Figure 9 shows another side view of impeller 100, Figure 10 shows a cross-sectional view of impeller 100 along line X-X', Figure 11 shows another side view of impeller 100 with blades adjusted to 5 degrees, Figure 12 shows another side view of impeller 100 with blades adjusted to 10 degrees, and Figure 13 shows another side view of impeller 100 with blades adjusted to 17 degrees.

[0028] The impeller 100 may be configured to rotate circumferentially 170 around the shaft axis 150 during use to drive a load, such as in a generator that may have a fixed-speed shaft. In the embodiment shown in Figure 4, for example, the circumferential direction 170 is counterclockwise when viewed from the upstream side of the impeller 100. However, in other embodiments, the circumferential direction 170 may be clockwise when viewed from the upstream side of the impeller 100.

[0029] The impeller 100 may include a hub 110 and a plurality of blades 120 extending from the hub 110. In some embodiments, the blades 120 are evenly spaced around the outer circumference of the hub 110. In some embodiments, the blades 120 are arranged spirally on the hub 110.

[0030] In some embodiments, each of the multiple blades 120 of the impeller 100 has the same shape and dimensions.

[0031] In the embodiment shown in Figure 1, the impeller 100 includes five blades 120. However, in other embodiments, the impeller 100 may include two blades, three blades, four blades, or more than five blades.

[0032] Each blade 120 of the impeller 100 may include a root 122 located on the hub 110, a tip 124 facing the root 122 and defining the outermost range of the blade 120, a leading edge 126 on the upstream portion of the impeller 100, a trailing edge 128 on the downstream portion of the impeller 100, an upstream pressure surface 130 of the blade 120, and a downstream suction surface 132 of the blade 120.

[0033] In some embodiments, the blades 120 are adjustable pitch blades. For example, this can help achieve high efficiency over a wide range of flow (for example, when the impeller 100 drives a generator with a fixed-speed shaft). In some such embodiments, for example, as shown in Figure 10, the blades 120 of the impeller 100 include pivot ends 123 that are pivotably coupled to blade links 111 of the hub 110 within the hub 110. The coupling between the pivot ends 123 and the blade links 111 may allow the blades 120 of the impeller 100 to pivot relative to the hub 110 about their respective pivot axes 180. In some embodiments, the control system of the impeller 100 can control the pivoting of the blades 120 relative to the hub 110 by pivoting the pivot ends 123 and / or the blade links 111.

[0034] In some embodiments, the blade 120 can pivot over a pivot range starting from 0 degrees when fully open, ranging from a blade angle of 5 degrees to a blade angle of 25 degrees. For example, as shown in Figures 11 to 13, the blade 120 can pivot up to an angle of 5 degrees (Figure 11), up to an angle of 10 degrees (Figure 12), or up to an angle of 17 degrees (Figure 13), to obtain high efficiency over a range of flow. In some embodiments, the blade 120 can pivot over a pivot range of about 15 degrees. In some embodiments, the blade 120 can pivot over a pivot range of about 20 degrees. In some embodiments, the blade 120 can pivot over a pivot range of about 25 degrees.

[0035] In some embodiments, the blade 120 can be pivoted to close the impeller and prevent water from passing through it.

[0036] In some embodiments, the pivot axis 180 of the blade 120 is angled with respect to the shaft axis 150 of the impeller 100. The pivot axis 180 may be perpendicular to the shaft axis 150 or not. For example, the pivot axis 180 of the blade 120 can be angled with respect to the shaft axis 150 of the impeller 100 at an angle β greater than 90 degrees, such that the pivot axis 180 of the blade 120 is angled downstream. In Figure 10, for example, the pivot axis 180 is angled at approximately 97 degrees with respect to the shaft axis. In other embodiments, the pivot axis 180 can be angled at an angle of approximately 8 to 45 degrees with respect to the shaft axis.

[0037] The position of the pressure center relative to the blade pivot axis 180 and the position of the blade's center of mass (see, for example, Figures 19-20) significantly affect the mechanical load of the blade pivot system and, similarly, the operating behavior of the turbine. Generally, a choice must be made as to whether a pivotable turbine blade exhibits self-closing or self-opening behavior. The decision to choose self-closing or self-opening must involve various considerations, and both options can commonly be found in practice. For example, it may be preferable to choose a self-opening design that limits the maximum unrestrained speed to protect associated equipment such as generators. On the other hand, self-closing behavior can be beneficial as it facilitates blade adjustment during load tracking. Under maximum power output conditions, the pressure center may be located near the radial direction of the blade's mid-span and closer to the trailing edge than the leading edge, for example, at approximately 60-80 percent of the mid-span chord length. Typically, the blade pivot axis may be located at approximately 20-30 percent of the mid-span chord length. Thus, the water pressure distribution tends to form a moment of closure around the blade pivot axis. The position of the blade's center of mass can be selected considering the hydraulic load, as well as the allowable stress of the operating system components and the available space. Generally, if the blade's center of mass is located downstream of the blade pivot axis, the blade exhibits self-closing behavior when the impeller rotates around the shaft axis. In contrast, if the blade's center of mass is located upstream of the blade pivot axis, the blade exhibits self-opening behavior. Positioning the blade's center of mass closer to the blade pivot axis tends to reduce the magnitude of the moment of inertia. The position of the blade's center of mass can be determined by both the thickness distribution and positioning of the blade geometry, as well as the mass distribution within the blade. For example, a hollow blade can be constructed with variable wall thickness to facilitate positioning the blade's center of mass at a desired location relative to the blade's pivot axis.

[0038] In some embodiments, the blade pivot axis may be perpendicular to the shaft axis. This configuration can simplify the operating system compared to embodiments that utilize a blade pivot axis that is not perpendicular to the shaft axis. For example, the blade pitch angle adjustment system utilizes a set of mechanical links, and a ball joint can be used when the blade pivot axis is not perpendicular to the shaft axis, as shown in Figure 20. However, when the blade pivot axis is perpendicular to the shaft axis, a cylindrical bushing or bearing can be used.

[0039] For example, as shown in Figures 1 and 10, the shape of the root 122 of each pivotable blade 120 can conform to the shape of the outer surface of the hub 110 during the rotation of the blade 120 from the maximum pitch of the blade 120 to the minimum pitch of the blade 120. For example, in some embodiments, the outer surface of the hub 110 swept by the root 122 from the maximum pitch of the blade 120 to the minimum pitch of the blade 120 is shaped spherically, and the root 122 in the hub 110 may have a generally spherical sweep shape over the pivot range of the blade 120 from the maximum pitch of the blade 120 to the minimum pitch of the blade 120. This can reduce the gap between the hub 110 and the root 122 over the pivot range of the blade 120 from the maximum pitch of the blade 120 to the minimum pitch of the blade 120. The gap between the hub 110 and the root 122 can be dangerous to fish, as they may get caught in the gap and then cut or otherwise injured. The gap can also lead to a loss of hydraulic efficiency, as well as localized regions of turbulence, increased fluid shear forces associated with accelerated flow, and potential cavitation.

[0040] In some embodiments, the impeller 100 is integrated with the turbine 200 (for example, as shown in Figures 14 to 16). In some embodiments, the shape of the tip 124 of each pivotable blade 120 may conform to the inner surface shape of the turbine 200 housing during the rotation of the blade 120 from its maximum pitch to its minimum pitch. For example, in some embodiments, the inner surface of the turbine 200 housing swept by the tip 124 from its maximum pitch to its minimum pitch is shaped spherically, and the tip 124 may have a generally spherical sweep shape over the pivot range of the blade 120 from its maximum pitch to its minimum pitch. For example, this reduces the gap between the blade tip 124 and the turbine 200 housing over the pivot range of the blade 120 from its maximum pitch to its minimum pitch. The gap between the blade tip 124 and the turbine housing 200 can be dangerous to fish, as they may get trapped in the gap and subsequently cut or otherwise damaged. The gap can also lead to a loss of hydraulic efficiency, as well as localized areas of turbulence and potential cavitation.

[0041] In some embodiments, the spherical hub D sph_h The diameter of the impeller and the diameter of the impeller D R The ratio is approximately 0.4 to 0.5, for example, about 0.42 to 0.45.

[0042] In the embodiments shown in Figures 10 to 16, the gap is reduced at the hub 110 (due to the generally spherical shape of the hub 110 at the root 122 and the generally spherical sweep shape of the root 122 at the hub 110), and the gap is reduced at the blade tip 124 (due to the generally spherical sweep shape of the blade tip 124 over the pivot range of the blade 120 and the generally spherical shape of the turbine 200 housing at the blade tip 124). However, in some embodiments, the gap is reduced at the hub 110 but not at the blade tip 124. For example, in some embodiments, the trailing edge 128 can overhang (i.e., extend beyond the spherical portion of the turbine 200 housing, as shown in Figure 17) so that the gap is not minimized at the blade tip 124. This allows for more flow through the turbine 100 while maximizing the blade surface area to reduce the risk of cavitation (compared to an impeller without a trailing edge overhang). In some examples, the leading edge 126 may not overhang or extend upstream of the discharge ring of the turbine housing, but may be parallel to or below the upstream end of the discharge ring. This is because an overhang at the leading edge could increase the risk of injury to fish entering the turbine impeller. However, in some embodiments, the leading edge of the impeller may overhang or extend upstream of the discharge ring of the housing. This can occur when an impeller with spherical geometry is placed in a turbine housing having a cylindrical shape, which can result in improved fish safety compared to conventional turbine impellers.

[0043] In some embodiments, the turbine 200 housing includes an exhaust ring (e.g., a spherical exhaust ring). In some embodiments, the exhaust ring has a removal segment, which is assembled removably from either outside or inside the turbine. In some embodiments, the exhaust ring is axially split (e.g., for removal along the shaft axis 150). In some embodiments, the exhaust ring is radially split (e.g., for removal perpendicular to the shaft axis 150).

[0044] For example, as shown in FIG. 6, the blade 120 may have a thick leading edge 126 having a thickness T LE and may have a thickness T.

[0045] In some embodiments, the thickness T of the leading edge of the blade 120 LE can be at least about 50 mm. In some embodiments, the thickness T of the leading edge of the blade 120 LE can be the same as or greater than the length of the fish species of interest in the area where the turbine including the impeller 100 is installed. For example, smolt salmon have an average length of about 100 - 200 mm. Thus, the thickness T of the leading edge of the blade 120 intended for use in an area where smolt salmon are present LE can be 100 mm - 200 mm or more. The leading edge thickness intended for use in an area where adult eels are moving needs to be 75 mm - 200 mm or more, and it can be important to avoid gaps such as between the leading edge and the hub or between the leading edge and the exhaust ring that might catch and cut slender fish such as eels. In some examples, the leading edge thickness can be between about 100 mm and about 700 mm.

[0046] In some embodiments, the ratio of the thickness T of the leading edge LE to the diameter D of the impeller R (i.e., T LE / D R ) can be from about 0.03 to about 0.35, for example, from about 0.06 to about 0.25, for example, from about 0.08 to about 0.14.

[0047] In some embodiments, the thickness of the blade 120 may be tapered from the leading edge 126 to the trailing edge 128. The thickness of the blade 120 may be tapered such that the pressure surface 130 and the suction surface 132 intersect at the trailing edge 128 of the blade 120.

[0048] In some embodiments, the blade 120 may have a consistent thickness from the root 122 to the tip 124. In other embodiments, the thickness of the blade 120 may be variable. In some embodiments, the thickness of the blade 120 may be greater at the tip 124 of the blade 120 than at the hub 110. The tangential velocity of the blade 120 increases from the root 122 to the tip 124. As a result, the orthogonal component of the strike velocity of the blade 120 encountering a fish near the tip 124 may be greater than the orthogonal component of the strike velocity of the blade 120 encountering a fish near the root 122. To reduce the risk of mass mortality in the region where the fish 300 are most likely to experience high strike velocities, the blade may have a thick leading edge, as discussed, and in addition, or alternatively, a sloped leading edge.

[0049] For example, as shown in Figure 4, the blades 120 of the impeller 100 may have a leading edge 126, which is inclined at an angle θ at one or more locations along the leading edge 126 (e.g., locations t, m, h). (The curve can be drawn along the vertex of the blade's stationary region from the hub to the tip, defining the leading edge of the blade. A tangent drawn at any point along this curve can be measured with respect to a cylindrical surface coaxial with the rotation axis of the turbine impeller, intersecting the point. The inclination angle is measured between the tangent and a vector that lies on the cylindrical surface, is perpendicular to the leading edge, and coincides with the leading edge intersection.)

[0050] The mortality rate of fish is the normal component of the strike velocity at the time of impact. N It is a function of . Therefore, the normal component w of the strike velocity at the time of collision N Reducing the angle of inclination reduces fish mortality. Therefore, compared to a blunt blade at the leading edge where the inclination angle θ is other than 90 degrees, fish mortality is reduced.

[0051] In some embodiments, the leading edge 126 at a certain location can be inclined at an angle θ of about 25 to about 45 degrees. In some embodiments, the leading edge 126 at a certain location can be inclined at an angle θ of about 30 degrees.

[0052] In some embodiments, the leading edge 126 may be inclined at the tip 124. As described above, the strike velocity increases from the base 122 of the blade 120 to the tip 124 of the blade 120, with the tip 124 of the blade 120 having the maximum strike velocity. Therefore, by providing a leading edge 126 with an inclination angle θ at the tip 124 of the blade 122, the mortality rate, at which the fish 300 are more likely to experience a fatal impact, can be reduced. Providing a leading edge 126 inclined at the tip 124 can also help prevent, for example, the accumulation or buildup of debris at the tip 124.

[0053] In some embodiments, the leading edge 126 may be inclined at a location between the base 122 and the tip 124. For the same reasons described above with respect to providing a leading edge 126 with an inclination angle at the tip 124, providing a leading edge 126 with an inclination angle θ in the region between the base 122 and the tip 124 can reduce the mortality rate, which may be relatively high for the fish 300 to experience a fatal impact.

[0054] In some embodiments, for example as shown in Figure 4, the inclination angle θ at the tip 124 of the blade 922 can be smaller than the inclination angle θ at the base 120 and / or between the base 122 and the tip 124.

[0055] In some embodiments, the leading edge 126 may be inclined at the base 122. The inclination angle of the leading edge 126 of the blade 120 at the base 122 can be about 10 to about 90 degrees, for example, about 25 to about 45 degrees. In addition to improving the survival of fish 300 that collide with the blade 120 at the base 122, providing an inclined leading edge 126 at the base 122 helps to prevent the accumulation or buildup of debris at the point where the base 122 of the blade 120 contacts the hub 110.

[0056] In some embodiments, for example, as shown in Figure 4, the leading edge 126 of the blade 120 can be inclined so that the leading edge 126 is arc-shaped. In other embodiments, the leading edge 126 may have a C-shape, a semicircular shape, a parabolic shape, a conical shape, a saddle shape, or any other shape.

[0057] In some embodiments, for example as shown in Figure 4, the leading edge 126 of the blade 120 can be curved toward the trailing edge 128 of the blade 120 near the hub 110, such that the leading edge 126 has a concave shape. This makes it possible, for example, to achieve a smaller angle at the tip 124 while minimizing the cantilevered tip.

[0058] In some embodiments, the leading edge 126 of the blade 120 at the root 122 can be inclined at a first angle θ, and the leading edge 126 of the blade 120 at the tip 124 can be inclined at the same angle θ.

[0059] In some embodiments, the root 122 of the leading edge 126 of the blade 120 is positioned along the radial axis 160 of the impeller 100, and the tip 124 of the leading edge 126 extends beyond the radial axis 160 in the circumferential direction 170. Thus, the leading edge 126 of the blade 120 can be cantilevered.

[0060] Since the tip 124 at the leading edge 126 extends beyond the radial axis 160 in the circumferential direction 170, a smaller angle can be achieved. This allows for a smaller strike velocity w during impact. NThe normal component of the angle may decrease. However, as the angle continues to decrease, the structural stiffness of the blade may also decrease. This could increase the manufacturing cost required to maintain the minimum structural stiffness requirements of the blade. Structural stiffness may be required, for example, to keep the tip 124 of the blade 120 within the tight tolerances of the turbine housing.

[0061] In some embodiments, the root 122 of the leading edge 126 of the blade 120 and the tip 124 of the leading edge 126 of the blade 120 may both be positioned along the radial axis 160.

[0062] For example, as shown in Figure 6, the blades 120 of the impeller 100 may have a curved leading edge 126 when viewed along an axis perpendicular to the shaft axis 150 (i.e., from the side of the impeller 100). For example, as shown in Figure 6, when the blades 120 are viewed from the side of the impeller 100, the leading edge 126 of the blades 120 (from the root 122 to the tip 124) may curve away from the upstream end of the impeller 100 and then curve back toward the upstream end of the impeller 100.

[0063] In some embodiments, the cross-section at the root can have substantially greater thickness near the leading edge than any other cross-section taken through the blade at any other radius. Its size and location can cause the blade surface to intersect the hub at an obtuse angle along the entire leading edge. This is important to allow for a uniform pressure distribution on the blade's suction surface (i.e., the downstream surface). Alternatively, if the downstream blade surface near the leading edge intersects the spherical hub at a near-perpendicular or acute angle, a localized area of ​​low pressure can form near the intersection of the blade surface and the spherical hub at this location, resulting in an undesirable reduction in the margin against cavitation.

[0064] In some embodiments, for example, as shown in Figures 4 and 6, the blades 120 of the impeller 100 may have an arc-shaped leading edge 126 when viewed along the shaft axis 150 and along an axis perpendicular to the shaft axis 150 (i.e., from the side of the impeller 100). However, in some embodiments, the leading edge 126 may be arc-shaped only when viewed along the shaft axis 150 or only when viewed along an axis perpendicular to the shaft axis 150.

[0065] For example, as shown in Figure 6, the blade 120 of the impeller 100 may have a curved leading edge 126. That is, the stacking line along the leading edge of the blade may have a non-zero angle with respect to the radial line at the intersection with the end wall. In some embodiments, the blade may have a leading edge with negative curvature, meaning that the dihedral angle between the blade suction surface and the end wall is acute. In some embodiments, the blade may have a leading edge with positive curvature, meaning that the dihedral angle between the blade pressure surface and the end wall is acute. In some embodiments, the dihedral angle between the blade pressure wall and the hub may differ from the dihedral angle between the blade pressure wall and the housing. In some examples, the leading edge 126 has a curvature between approximately -25°-(90~75)° at the hub and approximately -15°-(90~75)° at the tip. The blade may have a variety of stagger angles, where stagger angle refers to the angle between the blade chord line and the axial flow direction.

[0066] In some embodiments, the trailing edge 128 may have an S-shape, as shown in Figures 6 and 18, for example. The first portion 133 of the trailing edge may be concave, and the second portion 135 of the trailing edge (for example, the portion of the trailing edge located further from the hub than the first portion) may be convex. For example, this can result in a desirable pressure distribution across the blade 120 and help form a desirable fluid velocity distribution leaving the impeller and entering the draft tube or diffuser.

[0067] In some embodiments, for example, as shown in Figure 6, the trailing edge 128 may have a similar arc shape to the leading edge when viewed along the shaft axis. This maximizes the blade surface area, which can be important for achieving cavitation-free operation. Fish-safe impellers can utilize fewer blades compared to conventional designs. For example, a conventional Kaplan turbine operating at a 10-meter drop and positioned 3 meters above the discharge (i.e., drawing a 3-meter suction) can utilize five blades. Fish-safe impellers with thicker blades can be designed to replace conventional impellers without altering the conventional water flow path, but these fish-safe impellers may benefit from a reduction in the number of blades, such as four blades, while still enabling the same flow rate and power output as conventional impellers. To achieve a similar pressure distribution, each of the remaining blades may need to have a larger surface area than in conventional impellers. To achieve the required surface area, the trailing edge may intersect the discharge ring surface and the hub at an acute angle. In some embodiments, the trailing edge intersects the discharge ring at an inclusive angle between 5 and 110 degrees, such as between 10 and 45 degrees.

[0068] The cross-section of the blade 120 may be taken at the root 122, at the tip 124, or at a location between the root 122 and the tip 124. Each cross-section is measured along a straight line from the leading edge 126 to the trailing edge 128, with respect to the chord length L. C It may have a chord length L at the tip 124. In some embodiments, the chord length L at the tip 124 is C The chord length L at the root 122 is C It is longer than that. For example, in some embodiments, the chord length L at the tip 124 is longer. C The chord length L at the root 122 is C It is approximately 1.6 to 2.5 times longer than [another product].

[0069] In some embodiments, the chord length L at the tip 124 C Impeller diameter D R The ratio to (i.e., L C,t / D R ) may be less than approximately 0.9.

[0070] By providing an inclined leading edge 126, the orthogonal component of the strike velocity is effectively reduced, allowing the impeller 100 to rotate at a higher speed, improving the power-to-speed ratio and economic competitiveness of the impeller 100 while maintaining safe passage for fish. In some embodiments, the impeller 100 is configured to rotate such that the orthogonal component of the strike velocity is about 7 m / s or less to allow safe passage for fish (e.g., for salmonid fish). In some embodiments, the impeller 100 is configured to rotate such that the orthogonal component of the strike velocity is about 11 m / s or less to allow safe passage for fish (e.g., for eels). In some embodiments, even higher orthogonal strike velocities of up to about 20 m / s result in very high survival rates for aquatic organisms, such as survival rates exceeding 98%. In some embodiments, the impeller has a tangential velocity of up to 20-40 m / s at the tip, while still achieving very high survival rates for aquatic organisms.

[0071] The impeller 100 and / or blade 120 can be made of any suitable material and can be formed by any suitable process. In some embodiments, the impeller 100 and / or blade 120 are made of molded carbon / fiberglass and resin. In such embodiments, the blade 120 may include a core made of lightweight foam. In some embodiments, the impeller 100 may be made of a metal such as bronze or stainless steel and can be formed by casting, including hollow casting which is machined into a final shape. In some embodiments, the impeller 100 and / or blade 120 are hollow. In some embodiments, the impeller 100 is made of a composite material and is manufactured via conventional methods of composite construction. For example, the impeller 100 may have a sandwich composite structure, or it may include a shear web inside the structure, or it may be made as a monocoque structure with thick walls. In some embodiments, the impeller 100 is made of an elastomer or polymer and has reinforcing materials dispersed locally or throughout its interior.

[0072] The blade 120 may have a hybrid structure. In some embodiments, the leading edge 126 of the blade 120 is armored. The leading edge 126 may include a coating. The tip 126 may be made of metal. In some embodiments, the blade tip 124 is formed using a thick layer of ablative material so that the blade tip 124 can wear inward within the inner diameter of the turbine housing (for example, as shown in Figures 14–16). One or more blades 120 may include an anti-cavitation lip. The anti-cavitation lip may include a lip extending from the blade tip 124 along at least a portion of the length of the blade tip 124 between the leading edge 126 and the trailing edge 128. The anti-cavitation lip may be in the form of a flat plate. The anti-cavitation lip may help control the flow around the tip of the blade.

[0073] In some embodiments, the diameter D of the impeller 100 R It can be at least about 1.5 meters. In some embodiments, the diameter D of the impeller 100 R This can range from approximately 1.5 meters to approximately 7 meters, for example, from approximately 2 meters to approximately 5 meters. The diameter can correspond to the spherical diameter measured from the outer radius of the turbine blade.

[0074] Axial length L of impeller 100 R Diameter D of the impeller 100 downstream of the impeller 100 R The ratio to can be less than approximately 0.55, or it can be between approximately 0.25 and approximately 0.55. The impeller 100 has an axial tip length L defined as the distance between the tip 124 of the leading edge 126 and the tip 124 of the trailing edge 128. t It may have the following characteristics: In some examples, the size of the housing is such that the axial tip length L t It can be determined by...

[0075] Figure 20 shows that the pressure center 1930 and mass center 1940 of blade 1920 can be offset. For example, the pressure center 1930 may be located closer to the trailing edge 1928 of blade 1920 than the mass center 1940. The pressure center 1930 may also be closer to the top 1924 of blade 1920 than the mass center 1940 of blade. In some examples, the trailing edge 1928 overhangs or extends downstream of the spherical or cylindrical portion of the turbine housing. The mass center 1940 of the blade may be close to the pivot axis 1950 of the blade. Blade material can be one variable that influences the locations of the pressure center 1930 and mass center 1940 of blade 1920. Other variables may be axial tip length, leading edge thickness, and trailing edge overhang.

[0076] Blades with a trailing edge overhang may have a larger blade surface area compared to blades without a trailing edge overhang. However, blades with a trailing edge overhang may distribute more of the blade's weight downstream of the pivot axis compared to blades without a trailing edge overhang, potentially putting stress on the pivot axis. To mitigate the downstream weight distribution problem, blades may have a forward-sloping and thickened leading edge that helps optimize mass distribution.

[0077] Figure 20 shows an example of components for acting the blade 1920. However, as will be understood by those skilled in the art, other components and devices may also be used for acting the blade. The acting mechanism may include an oil-filled hub, an oil-free hub, or directional actuation of each blade.

[0078] As mentioned above, in some embodiments, the impeller 100 is integrated into the turbine 200 (for example, as shown in Figures 14 to 16). In Figures 14 to 16, the shaft axis 150 is perpendicular to the ground. However, in other embodiments, the shaft axis 150 can be horizontal to the ground, or at an angle between horizontal and perpendicular to the ground. In some embodiments, the impeller drives the shaft upstream of the impeller. In other embodiments, the impeller drives the shaft downstream of the impeller.

[0079] In some embodiments, the turbine 200 may include commonly known inlet and outlet elements. The inlet element may include, for example, a helical or semi-helical shape. In some embodiments, the inlet of the turbine 200 is intended to be connected to a pressure pipe, a penstock, or the discharge of a scroll case. The outlet element may include, for example, a draft tube. The draft tube may have a change in cross-sectional area suitable for recovering the velocity head. The draft tube may be straight or curved, as is appropriate given characteristics of the hydroelectric plant.

[0080] During operation, water flows into the turbine 200, passes through the stages of guide vanes (which may be fixed in a pitch as needed depending on the application, or adjustable as needed) if guide vanes are present, passes through the impeller 100, and is discharged into a diffuser or draft tube, from which it can enter a discharge channel or an outlet pipe that sends the discharged water to the discharge channel.

[0081] In some embodiments, the turbine 200 operates at a head of at least 1 meter. In some embodiments, the turbine 200 operates at a head of at least 10 meters. In some embodiments, the turbine 200 operates at a head of at least 20 meters. In some embodiments, the turbine 200 operates at a head of at least 30 meters. In some embodiments, the turbine 200 operates at a head of at least 40 meters.

[0082] In some embodiments, the impeller 100 can be incorporated into a turbine 200, and the turbine 200 can be part of a hydroelectric power plant that includes several turbines.

[0083] In some embodiments, the impeller 100 is retrofitted to an existing turbine or hydroelectric facility, and in retrofits, it is often important to minimize changes to the existing civil engineering and electrical infrastructure. For example, retrofits may have strict constraints on using an existing generator operating at a fixed shaft speed, all of which strictly limit the design envelope within which a fish-safe impeller is formed, with the impeller installed at a predetermined height relative to the water discharge height.

[0084] Referring to Figures 21 and 22, a hydraulic turbine impeller 2100 is introduced. The impeller 2100 may have the features described above with respect to the impeller 100. For example, the impeller 2100 may have blades pivotably connected to a hub.

[0085] The impeller 2100 in Figures 21-22 differs in that it has a non-circular or non-spherical hub 2110. The impeller 2100 may have a pseudo-polygonal hub 2110. The hub 2110 generally has a spherical shape, but may have multiple faces 2112. The faces 2112 may not correspond to the spherical shape of the hub 2110. In some embodiments, the multiple faces may have a curved or convex shape. The faces 2112 may have a spherical shape with a larger radius of curvature compared to other parts of the hub 2110. In other words, the multiple faces 2112 may have a smaller curvature than the other parts of the hub 2110. In some examples, the multiple faces 2112 are generally flat or planar. Each face 2112 may have a circular region or perimeter. As shown in Figure 21, the hub 2110 may have a cubic shape with a rounded portion. The hub 2110 may have four or more faces 2112, each face 2112 may have a circular shape. The faces 2112 may be spaced radially apart with respect to the longitudinal axis of the hub 2110. The faces 2112 may be configured to be coupled to blades 2120. In some examples, portions of the blades 2120 coupled to the faces 2112 may have a different shape or size relative to the faces 2112. According to some examples, each face 2112 may be flat or planar when viewed at an angle perpendicular to the face 2112. In some examples, the remaining parts of the hub 2110 other than the faces 2112 may be rounded. In some examples, the hub 2110 may have four blades 2120, and the root 2122 of each blade 2120 may be coupled to the hub 2110 at a face 2112. The hub may have a face 2112 for each impeller blade. Some examples may include more than four faces 2112 and more than four blades 2120, such as 6 to 10 faces and 6 to 10 blades 2120. The pseudo-polygonal hub 2110 can generate an increased cross-sectional area flow area compared to hubs of other shapes. For example, the periphery of a virtual spherical hub 2114 is shown in Figure 21. As seen in this example, space 2116 may exist between the virtual spherical hub 2114 and the periphery of the pseudo-polygonal hub 2110.These spaces 2116 can provide additional flow area, and increasing the cross-sectional flow area may reduce the average flow velocity for a given power output.

[0086] According to some embodiments, as shown in Figure 21, the leading edge 2126 of one or more blades 2120 may have a forward inclination in the rotational direction. For example, the root 2122 may be positioned on the radial axis 2160 of the impeller 2100, and the tip 2124 of the leading edge 2126 may extend beyond the radial axis 2160 in the circumferential direction 2170. The leading edge 2126 may have a concave shape, as shown in Figures 21 and 22.

[0087] The turbine may have a discharge ring 2153 as shown in Figure 22A. The discharge ring 2153 may be a segmented discharge ring having two or more segments connected along one or more planes perpendicular to the shaft axis 150. Two or more segments may also be connected along one or more planes parallel to the shaft axis 150. In some examples, two segments are connected along a single plane. In some embodiments, three or more wedge-shaped segments are connected along multiple planes. The segments can be connected via bolt holes 2152, among other fastening methods. As shown in Figure 22A, each segment of the discharge ring 2153 may have segmented surfaces for which a portion of its parts abuts and connects to one or more other parts in order to form the discharge ring 2153.

[0088] Figures 23-24 show embodiments in which the impeller 2100 has a trailing edge 2128 extending behind the downstream end 2180 of the hub 2110. In some examples, the leading edge 2126 cannot extend forward of the discharge ring or dome portion 2192 of the housing 2190, but the trailing edge can extend behind the dome portion 2192. The hub 2210 may have an upstream end 2178 and a downstream end 2180. As shown in Figure 23, the downstream end 2180 may be the surface of the hub 2110 that is furthest downstream in the longitudinal direction 2150. According to some examples, the root 2122 of the trailing edge 2128 may extend behind the downstream end 2180 in the longitudinal direction 2150. The distance by which the root 2122 extends behind the downstream end 2180 in the longitudinal direction 2150 may define the trailing edge overhang 2182.

[0089] As shown in Figure 24, the entire trailing edge 2128 may extend behind the downstream end 2180 of the hub 2110. In these examples, in addition to, or instead of, the trailing edge root overhang 2182, there may be a trailing edge tip overhang 2184. In some embodiments, the trailing edge root overhang 2182 may be larger than the trailing edge tip overhang 2184. In some examples, the root 2122 of the trailing edge 2128 may extend rearward or further downstream relative to the rest of the blade 2120.

[0090] During operation, the impeller 2100 may be enclosed by the turbine housing 2190, as shown in Figures 23 and 24. The housing 2190 may have an exhaust ring or a dome portion 2192. In some examples, the dome portion 2192 may surround a portion of the impeller 2100, as shown in Figure 24. According to some examples, the rear of the dome portion 2192 may be aligned radially with the downstream end 2180 of the hub 2110, i.e., along the axis 2130.

[0091] In some embodiments, the trailing edge 2128 of the blade 2120 may extend downstream of the dome portion 2192. In some embodiments, the trailing edge root overhang 2182 and the trailing edge tip overhang 2184 may be measured relative to the rear end 2194 of the dome portion 2192, rather than relative to the downstream end 2180. As shown in Figure 23, in some embodiments, the root 2122 of the trailing edge 2128 may extend behind the dome portion 2192, while the tip 2124 of the trailing edge 2128 may not extend behind the dome portion 2192. In some examples, the tip 2124 may be positioned forward relative to the rear of the dome portion 2192. In other embodiments, as shown in Figure 24, both the tip 2124 and root 2122 of the trailing edge may overhang the dome portion 2192 or extend behind the dome portion 2192. In some examples, the entire trailing edge 2128 may be positioned behind the dome portion 2192.

[0092] An impeller 2100 having a trailing-edge root overhang 2182 may have similar advantages regardless of whether the root overhang 2182 is measured from behind the hub 2110 or from behind the dome portion 2192. For example, the trailing-edge root overhang 2182 increases the chord length compared to a blade without an overhang, thereby increasing the surface area of ​​the blade 2120. This increased surface area can be achieved without increasing the spherical outer diameter of the impeller 2100. Additionally, extending the trailing edge 2128 downstream can reduce suction pressure and allow for a longer chord length, minimizing cavitation.

[0093] According to the exemplary embodiments shown in Figures 24 to 25B, the cross-section through the blade 2120 can be obtained along the line 25H-25H. The cross-section along line 25H-25H may correspond to the cross-section of the blade 2120 obtained at the root 2122. The cross-sectional shapes of the blade obtained at the root, mid-span, and tip are shown as an example in Figure 25B.

[0094] As shown in Figure 25B, the cross-section of the blade 2120 at line 25H-25H can have varying thicknesses. The thickness obtained near the trailing edge 2128 may be smaller than the thickness at the leading edge 2126. First root thickness t 1h The second root thickness t 2h It may be positioned closer to the trailing edge 2128 than the first root thickness t 1h The second root thickness t 2h It can become smaller. (ratio of chord length (t)) h First root thickness t as (chord length) 1h The second root thickness t may be approximately 0.03 to 0.1 at the root, approximately 0.01 to 0.05 in the middle span or midline of the blade 2120, and 0.01 to 0.05 at the tip. 2h The coefficient of gravity may be approximately 0.1 to 0.2 at the base, approximately 0.08 to 0.16 in the middle span or midline of blade 2120, and 0.05 to 0.11 at the tip.

[0095] According to some examples, the surface curvature of the cross-section at 25H–25H can have a first shape 2136 and a second shape 2138. The first shape 2136 may be rearward relative to the second shape 2138, and both the first shape 2136 and the second shape 2138 may be defined by a surface 2132 or a surface 2134. The first shape 2138 may be positioned closer to the trailing edge 2128 than the second shape 2136, and the second shape 2138 may be positioned closer to the leading edge 2126. In some embodiments, the minimum thickness of the second shape 2138 may be greater than the maximum thickness of the first shape 2136. In other examples, the maximum thickness of the second shape 2138 may be greater than the maximum thickness of the first shape 2136.

[0096] In some embodiments, the first shape 2136 may be convex, and the second shape may be concave. In some examples, the leading edge 2126 may have a concave shape, which may correspond to the thick leading edge 2126 of the blade 2120. In some examples, the leading edge 2126 may have an arc shape when viewed along an axis perpendicular to the shaft axis of the impeller 2100. A thick leading edge 2126 can enhance fish safety. Conversely, the trailing edge 2128 may be narrower than the leading edge 2126. In some examples, the trailing edge 2128 may be tapered. A narrow trailing edge 2128 can improve the efficiency of the impeller 2100 compared to an impeller without a narrow trailing edge. In some examples, the thickness distribution at the intersection of the root 2122 and the hub 2110 may be steep.

[0097] In some examples, a blade 2120 having a root 2122 that extends further downstream than the rest of the trailing edge 2128 and has a thickness distribution with a steep positive slope at the intersection of the root 2122 and the hub 2110 may result in an improved pressure distribution compared to a conventional blade. This can be shown, for example, in Figure 27, where the downstream surface 2118 near the root 2122 curves away from the radial line 2160. For example, pressure may be distributed more evenly across the entire surface of the blade 2120 compared to a conventional blade. An optimal pressure distribution may help reduce barotropic trauma in captured fish. Barotropic trauma refers to injuries caused by changes in atmospheric or hydrostatic pressure. An optimal pressure distribution may reduce other injuries caused by locally severe and uneven pressure distribution.

[0098] In the exemplary examples shown in Figures 26-27, the impeller 2100 may include a blade 2120 with a trailing edge 2128 that is curved or bent in the upstream direction. In other words, a portion of the trailing edge 2128 between the tip 2124 and the root 2122 may be positioned longitudinally upstream with respect to the trailing edge 2128 at the tip 2124 and the root 2122. A virtual line 2129 may be drawn from the tip 2124 to the root 2122 of the trailing edge 2128. The trailing edge 2128 may be positioned upstream with respect to the virtual line 2129, except at the tip 2124 and the root 2122. In some examples, a portion of the trailing edge 2128 may be positioned upstream with respect to the virtual line 2129. According to some embodiments, the entire trailing edge 2128 may be positioned upstream with respect to the virtual line 2129, except at the tip 2124 and the root 2122.

[0099] The upstream-curved trailing edge 2128 helps reduce the risk of cavitation on the downstream surface of the leading edge 2126 at the tip 2124 when the blade 2120 is inclined toward a closed or nearly closed position. In other words, when the blade 2120 is inclined toward a closed position, the upstream curvature of the trailing edge 2128 can create a gap between adjacent blades 2120, reducing the risk of cavitation. The upstream curvature of the trailing edge 2128 can mitigate high velocities and low pressures near the trailing edge 2128.

[0100] Figure 28 is a graph 2800 showing a comparison of the normalized chord distribution of the blade 2842 of this disclosure with that of conventional Kaplan blades 2844 and 2846. The x-axis 2810 is defined as the ratio of the blade radius to the blade's maximum radius (radius / maximum radius). The ratio at the tip is 1 because the maximum radius is at the blade tip. The y-axis represents the ratio of the chord length to the maximum chord length (chord / maximum chord). The maximum chord length is 1 at the blade tip because the tip section 2842 for the turbine of this disclosure has the maximum chord length. There are two sets of lines for each blade; the upper set of lines 2840 corresponds to the leading edge, or upstream region, of each blade, and the lower set of lines 2830 corresponds to the trailing edge, or downstream region, of each blade. This graph shows, among other features, that the turbine blades of this disclosure have a forward inclination, or tip inclination, in contrast to conventional blades that curve toward the longitudinal axis of the turbine.

[0101] It should be understood that the interpretation of the claims is intended to be based on the section describing embodiments for carrying out the invention, rather than the section describing the summary and abstract of the invention. The section describing the summary and abstract of the invention may describe, but not all, one or more exemplary embodiments of the invention(s) contemplated by the inventor, and is therefore not intended to limit the invention(s) and the appended claims in any way.

[0102] The present invention(s) have been described above using functional foundational elements that exemplify the realization of specific functions and their relationships. The boundaries of these functional components are defined as appropriate in this specification for explanatory purposes. Other boundaries may be defined, as long as the specific functions and their relationships are properly implemented.

[0103] The foregoing descriptions relating to specific embodiments are intended to fully illustrate the general nature of the invention(s) and will allow those skilled in the art to readily modify and / or adapt such specific embodiments to various uses without excessive experimentation and without departing from the general outline of the invention(s) by applying knowledge within the scope of the art. Such adaptations and modifications are therefore intended to be within the meaning and scope of equivalent embodiments disclosed herein, based on the teachings and guidance provided herein. It should be understood that the expressions and terms herein are for illustrative purposes only and not for limitation. Therefore, the terms and expressions herein should be interpreted by those skilled in the art in light of the teachings and guidance.

[0104] The scope and breadth of the present invention should not be limited by any of the exemplary embodiments described above, but should be defined solely in accordance with the following claims and their equivalents.

[0105] Further embodiments of the present invention can be further illustrated by the following numbered clauses.

[0106] 1. A hydraulic turbine impeller comprising a hub and a plurality of pivotable blades extending from the hub, wherein each of the plurality of pivotable blades comprises a root located on the hub, a tip opposite the root, and a leading edge opposite the trailing edge, and each of the plurality of pivotable blades is pivotable relative to the hub about its respective pivot axis, and for at least one blade, the leading edge at the root is positioned along the radial axis of the impeller, and the leading edge at the tip is cantilevered beyond the radial axis in the circumferential direction of the impeller, and the leading edge thickness is greater than the trailing edge thickness.

[0107] 2. The impeller according to Clause 1, wherein the trailing edge is positioned downstream of the downstream end of the hub with respect to at least one of the plurality of pivotable blades.

[0108] 3. The impeller according to Clause 2, wherein the tip of the trailing edge is located downstream of the downstream end of the hub.

[0109] 4. The impeller according to Clause 2, wherein the root of the trailing edge extends further downstream than the rest of the trailing edge.

[0110] 5. An impeller according to any one of the plurality of pivotable blades, wherein at least one pivotable blade has a cross section having a surface curvature having a first shape and a second shape at its base, and optionally the first shape is concave and the second shape is convex.

[0111] 6. The impeller according to Clause 5, wherein the maximum root thickness of the second shape is greater than the maximum root thickness of the first shape, and the first shape is positioned closer to the trailing edge than the second shape.

[0112] 7. The hub is an impeller as described in any one of clauses 1 to 6, comprising a plurality of planar surfaces.

[0113] 8. The impeller according to Clause 7, wherein one of the plurality of surfaces has a circular shape.

[0114] 9. The impeller according to clause 7 or 8, wherein each of the plurality of faces is coupled to the base of the pivotable blades of the plurality of pivotable blades.

[0115] 10. The impeller according to any one of the clauses 1 to 9, wherein the trailing edge of the pivotable blade of the plurality of pivotable blades curves upstream between the tip and root of the pivotable blade.

[0116] 11. An impeller according to any one of the clauses 1 to 10, wherein the thickness of the leading edge of the plurality of pivotable blades is greater than about 100 mm.

[0117] 12. A hydraulic turbine impeller comprising a hub and a plurality of pivotable blades extending from the hub, each of the plurality of pivotable blades comprising a root located in the hub, a tip opposite the root, and a leading edge opposite the trailing edge, each of the plurality of pivotable blades being pivotable relative to the hub about its respective pivot axis, and for at least one blade, the leading edge being arc-shaped when viewed along an axis perpendicular to the shaft axis of the impeller, and at least one of the plurality of pivotable blades having a cross-section in the hub having a surface having a first shape and a second shape, the first shape being concave and the second shape being convex.

[0118] 13. The impeller according to Clause 12, wherein the hub is shaped into a cube having rounded edges and one or more faces having a circular shape, the faces being radially spaced around the longitudinal axis of the hub.

[0119] 14. The impeller according to clause 12 or 13, wherein the root of the trailing edge extends further downstream than the rest of the trailing edge.

[0120] 15. A turbine comprising a housing defining an inlet and outlet for a flow of liquid, and an impeller positioned within the housing, wherein the impeller comprises a hub and a plurality of pivotable blades extending from the hub, each of the plurality of pivotable blades comprising a root positioned in the hub, a tip opposite the root, and a leading edge opposite the trailing edge, each of the plurality of pivotable blades being pivotable relative to the hub about its respective pivot axis, and for at least one blade, the leading edge at the root is positioned along the radial axis of the impeller, and the leading edge at the tip is cantilevered beyond the radial axis in the circumferential direction of the impeller, and at least one of the plurality of pivotable blades having a cross-section in the hub having a surface having a first shape positioned closer to the leading edge than a second shape, the first shape being concave, the second shape being convex, and the thickness of the leading edge being greater than the thickness of the trailing edge.

[0121] 16. The turbine according to Clause 15, wherein the hub is shaped into a cube having rounded edges and one or more faces.

[0122] 17. The turbine according to Clause 16, wherein each of the one or more surfaces has a circular shape.

[0123] 18. The turbine according to either clause 15 or 17, wherein the surfaces are radially spaced about the longitudinal axis of the hub.

[0124] 19. The turbine according to any one of the clauses 15 to 18, wherein the root of the trailing edge, the tip of the trailing edge, or both the root of the trailing edge and the tip of the trailing edge extend behind the downstream end of the hub.

[0125] 20. The turbine according to any one of the clauses 15 to 19, wherein the trailing edge of the plurality of pivotable blades is curved upstream between the tip and the root.

Claims

1. Hub and, The hub comprises a plurality of pivotable blades, each of the plurality of pivotable blades being The base located at the hub, The tip opposite the aforementioned base, The leading edge and, Includes, Each of the plurality of pivotable blades is pivotable relative to the hub about its own pivot axis. The aforementioned front edge thickness T ＬＥ The diameter D of the impeller Ｒ The ratio to is in the range of approximately 0.03 to approximately 0.

35. A hydraulic turbine impeller, wherein for at least one blade, the leading edge at the root is positioned along the radial axis of the impeller, and the leading edge at the tip is cantilevered across the radial axis in the circumferential direction of the impeller.

2. The impeller according to claim 1, wherein the ratio of the axial length of the impeller to the diameter of the impeller is less than approximately 0.

55.

3. The impeller according to claim 1, wherein the ratio of the chord length at the tip of each pivotable blade to the diameter of the impeller is less than about 0.

9.

4. The impeller according to claim 1, wherein each pivot shaft is angled with respect to the shaft axis of the impeller at an angle between approximately 8 degrees and approximately 155 degrees.

5. The impeller according to claim 1, wherein the outer surface of the hub, swept by the root of each pivotable blade during rotation from the maximum pitch to the minimum pitch of the blades, is shaped into a spherical form.

6. The base of each pivotable blade conforms to the shape of the outer surface of the hub during rotation from the maximum pitch to the minimum pitch of the pivotable blade. The impeller according to claim 1, wherein the tip of each pivotable blade has a generally spherical sweep shape over the pivot range from the maximum pitch to the minimum pitch of the pivotable blade.

7. The impeller according to claim 1, wherein the thickness of the leading edge of each pivotable blade is between approximately 100 mm and approximately 700 mm.

8. The impeller according to claim 1, wherein a portion of the leading edge at the tip of each pivotable blade is inclined at an angle between approximately 20 degrees and approximately 90 degrees with respect to the radial axis of the impeller.

9. The leading edge of each pivotable blade is arc-shaped when viewed along an axis perpendicular to the shaft axis of the impeller. The impeller according to claim 1, wherein the leading edge of each pivotable blade, when viewed along an axis perpendicular to the shaft axis of the impeller, curves away from the upstream end of the impeller at the root and curves back toward the upstream end of the impeller toward the tip.

10. The impeller according to claim 1, wherein the radius of curvature of one or more of the surfaces is greater than the radius of curvature of the rounded edge of the hub.

11. The impeller according to claim 1, wherein the first portion of the trailing edge is concave, the first portion of the trailing edge is convex, and the first portion of the trailing edge is positioned closer to the hub than the second portion of the trailing edge.

12. A housing that defines an inlet and outlet for the flow of liquid, Hub, and Multiple pivotable blades extending from the hub Including, a turbine impeller for a hydraulic turbine, Includes, Each of the aforementioned plurality of pivotable blades is The base located at the hub, The tip opposite the aforementioned base, The leading edge on the opposite side of the trailing edge, Includes, Each of the plurality of pivotable blades is pivotable relative to the hub about its own pivot axis. The aforementioned front edge thickness T ＬＥ The diameter D of the impeller Ｒ The ratio to is in the range of approximately 0.03 to approximately 0.

35. A turbine in which, for at least one blade, the leading edge at the root is positioned along the radial axis of the impeller, and the leading edge at the tip is cantilevered in the circumferential direction of the impeller, extending beyond the radial axis.

13. The tip of each pivotable blade conforms to the shape of the discharge ring of the housing during the rotation of the blade from the maximum pitch to the minimum pitch. The turbine according to claim 12, wherein the inner surface of the discharge ring of the housing, which is swept by the tip of each pivotable blade during the rotation of the pivotable blade from the maximum pitch to the minimum pitch, is shaped into a spherical form.

14. The turbine according to claim 12, wherein the discharge ring of the housing has a removable segment configured to be assembled so as to be removable from either the outside or the inside of the turbine, and the discharge ring of the housing is divided.

15. The turbine according to claim 12, wherein the root of the trailing edge extends further downstream than the rest of the trailing edge.

16. Hub and, Multiple pivotable blades extending from the hub, Including, each of the plurality of pivotable blades is The base located at the hub, The tip opposite the aforementioned base, The leading edge on the opposite side of the trailing edge, Includes, Each of the plurality of pivotable blades is pivotable relative to the hub about its own pivot axis, and for at least one blade, the leading edge at the root is positioned along the radial axis of the impeller, and the leading edge at the tip is cantilevered in the circumferential direction of the impeller, extending beyond the radial axis. A hydraulic turbine impeller wherein, in the meridian section, the trailing edge at the root of the blade is located further downstream than the trailing edge at the tip of the blade.

17. The impeller according to claim 16, wherein the trailing edge of at least one of the plurality of pivotable blades extends downstream of the downstream end of the hub.

18. The impeller according to claim 16, wherein at least one of the plurality of pivotable blades has a cross section having a surface curvature having a first shape and a second shape at its base, the first shape being concave and the second shape being convex.

19. The impeller according to claim 16, wherein the hub includes a plurality of planar surfaces, the surfaces being radially spaced around the longitudinal axis of the hub.

20. The impeller according to claim 16, wherein the trailing edge of one of the plurality of pivotable blades is curved upstream between the tip and root of the pivotable blade.

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