WO2016090422A1

WO2016090422A1 - A blade for a vertical axis turbine, a turbine comprising the blade and a method of operation of the turbine

Info

Publication number: WO2016090422A1
Application number: PCT/AU2015/050760
Authority: WO
Inventors: Edward Howard SPICER
Original assignee: Spicer Edward Howard
Priority date: 2014-12-11
Filing date: 2015-12-02
Publication date: 2016-06-16
Also published as: GB2547872B; NZ732950A; AU2015362077A1; GB201709934D0; GB2547872A; AU2015362077B2

Abstract

There is provided a blade for a vertical axis turbine, wherein the blade defines a tubercled leading edge and a trailing edge and is twisted through approximately 60° for rotating about the axis of the turbine in use, the blade defining a series of landmarks as described herein for increasing operational efficiency as compared to conventional turbine blades

Description

A BLADE FOR A VERTICAL AXIS TURBI NE, A TURBIN E COMPRISING TH E BLADE AND A M ETHOD OF OPERATION OF THE TURBIN E

Field of the Invention

[1] The present invention relates to a turbine blade and in particular to a blade for a vertical axis turbine.

[2] The blade has been developed primarily for use in a helical (Gorlov) turbines and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

Background

[3] The need for off-grid power generation is increasing, especially for reducing dependence on fossil fuels, providing power to rural areas and the like.

[4] As such, existing arrangements employ turbines to harness naturally abundant wind and water power for the purposes of electricity generation.

[5] These turbines utilise blades for the generation of rotational forces. In one application, submerged turbine assemblies are used for the purposes of harnessing power from multidirectional water flow, such as from river, tidal flows and the like.

[6] Various turbine assemblies suitable for submerged use are known, such that the Wells, Darrieus, McGormick, Savonis and the Gorlov Helical turbine, each having certain advantages and disadvantages.

[7] The present invention seeks to provide a blade for a vertical axis turbine, a turbine comprising the blade and a method of operation of the turbine, which will provide superior performance characteristics as compared to conventional blade and turbine arrangements.

[8] It is to be understood that, if any prior art information is referred to herein, such reference does not constitute an admission that the information forms part of the common general knowledge in the art, in Australia or any other country.

Summary of the Disclosure

[9] There is provided herein a blade for a vertical axis turbine mimicking the pectoral fin of a humpback whale. The Inventor, intrigued by the turning ability of humpback whales, modified the long-standing vertical axis Gorlov helical turbine design to mimic the pectoral fin of the humpback whale. [10] Through extensive computational fluid dynamic (CFD) simulation design adjustment iterations the specific blade design, comprising the specific dimension as disclosed herein (especially with reference to the Best Mode given below), has been shown through CFD modelling to provide power percentage improvements of 53.8, 62.9 and 74.7% for revolutions per minute of 10, 20 and 30 respectively.

[11] These CFD results are disclosed in the report entitled "CFD modelling of Gorlov helical turbine blade" prepared by the CSI O under commission from the Inventor, of which, the entire contents of this report or incorporated herein by reference.

[12] This consultancy performed by the CSIRO generated and assessed the performance of a Gorlov turbine featuring biomimetic turbine blades inspired by the pectoral fin of a humpback whale.

[13] Two different turbine designs were considered - the first featuring 3 blades with a 60° downward twist with each blade having a constant airfoil section along its entire length - the second similarly 3 blades with a 60° downward twist, but with each blade taking on the appearance of the whale's pectoral fin including featuring tubercles.

[14] The CFO investigation indeed shows the turbine having the new blade design to achieve superior performance; at various operating speeds tested, with improved power outputs of 48-74 percent as compared to the normal-blade Gorlov turbine equivalent, as is shown in Table 1 below.

[15] The inventor subsequently performed the above extensive CFD simulation design adjustments to arrive at the best mode, a blade having the dimensions substantially as given in Table 2 below entitled "Best Mode Dimensions", cross referencing table 10.

[16] With the foregoing in mind, in accordance with a preferred embodiment, there is provided a blade for a vertical axis turbine, wherein the blade defines: a tubercled leading edge and a trailing edge; and is twisted through approximately 60° for rotating about the axis of the turbine in use, wherein the blade defines a series of landmarks, each landmark having: a twist of plane about the axis of the turbine from 0° to 60°; and a percentage width of the maximum width of the blade from 0% to 100%, wherein the landmarks (numbered with Z numbering for convenience), comprise: Z03 having a twist of approximately 18° and a percentage width of approximately 100% and Z09 having a twist of approximately 36° and a percentage width of approximately 80%

[17] The landmarks may further comprise landmark Z00 having a twist of approximately 0° and a percentage width of approximately 60%

[18] The landmarks may further comprise landmark Z01 having a twist of approximately 6° and a percentage width of approximately 60%

[19] The landmarks may further comprise landmark Z02 having a twist of approximately 12° and a percentage width of approximately 80% [20] The landmarks may further comprise landmark Z04 having a twist of approximately 24° and a percentage width of approximately 84%

[21] The landmarks may further comprise landmark Z05 having a twist of approximately 26.4° and a percentage width of approximately 88%

[22] The landmarks may further comprise landmark Z06 having a twist of approximately 28.8° and a percentage width of approximately 80%

[23] The landmarks may further comprise landmark Z07 having a twist of approximately 31.2° and a percentage width of approximately 82%

[24] The landmarks may further comprise landmark Z08 having a twist of approximately 33.6° and a percentage width of approximately 76%

[25] The landmarks may further comprise landmark Z10 having a twist of approximately 40.5° and a percentage width of approximately 68%

[26] The landmarks may further comprise landmark Zll having a twist of approximately 43.5° and a percentage width of approximately 64%

[27] The landmarks may further comprise landmark Z22 having a twist of approximately 45° and a percentage width of approximately 52%

[28] The landmarks may further comprise landmark Z13 having a twist of approximately 46.5° and a percentage width of approximately 48%

[29] The landmarks may further comprise landmark Z14 having a twist of approximately 48° and a percentage width of approximately 44%

[30] The landmarks may further comprise landmark Z15 having a twist of approximately 49.5° and a percentage width of approximately 40%

[31] The landmarks may further comprise landmark Z16 having a twist of approximately 51° and a percentage width of approximately 34%

[32] The landmarks may further comprise landmark Z17 having a twist of approximately 52.5° and a percentage width of approximately 36%

[33] The landmarks may further comprise landmark Z18 having a twist of approximately 54° and a percentage width of approximately 32%

[34] The landmarks may further comprise landmark Z19 having a twist of approximately 55.5° and a percentage width of approximately 32%

[35] The landmarks may further comprise landmark Z20 having a twist of approximately 57° and a percentage width of approximately 28%

[36] The landmarks may further comprise landmark Z21 having a twist of approximately 58.5° and a percentage width of approximately 28% [37] The landmarks may further comprise landmark Z22 having a twist of approximately 60° and a percentage width of approximately 24%

[38] The tubercled edge may define a plurality of tubercles.

[39] The plurality of tubercles define widthwise dominant tubercles and widthwise subservient tubercles.

[40] The widthwise dominant tubercles and widthwise subservient tubercles are interposed.

[41] The blade may further define a non-tubercled trailing edge.

[42] The trailing edge may define a non-linear trailing edge.

[43] The non-linear trailing edge may comprise an intermediate trailing edge bounded by respectively laterally adjacent superior and inferior trailing edges.

[44] The intermediate trailing edge may be substantially lateral.

[45] The superior trailing edge may be substantially concave.

[46] The inferior trailing edge may be substantially convex.

[47] At least a subset of the plurality of tubercles may have breadthwise prominence.

[48] The plurality of tubercles may define breadthwise dominant tubercles and breadthwise subservient tubercles.

[49] The breadthwise dominant tubercles may be widthwise dominant tubercles

[50] The at least a subset of the plurality of tubercles may define a foil having a leading-edge breadth and a respectively narrower trailing edge breadth.

[51] The foil may be tapered.

[52] The blade may be adapted for a helical poise.

[53] The blade may be twisted for helical poise.

[54] The blade may comprise distal ends adapted for helical poise.

[55] The helical poise blade may be left-handed helical poise

[56] The helical poise may be pitched at substantially 60°

[57] The blade may define a non-linear width profile.

[58] The non-linear width profile may define a supine width and a respectively narrower inferior width.

[59] The non-linear width profile further may define an intermediate width being greater than the supine width and the inferior width.

[60] The blade may be dimensioned such that when used in a three-blade vertical axis turbine placed in a flow rate and rotating at a rotational speed, the three blade vertical axis turbine may be able to produce greater than a threshold of power. [61] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 10 rpm and the power may be greater than substantially 40 W.

[62] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 20 rpm and the power may be greater than substantially 100 W.

[63] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 30 rpm and the power may be greater than substantially 160 W.

[64] The flow rate may be greater than substantially 7 m/s, the rotational speed may be greater than substantially 10 rpm and the power may be greater than substantially 450 W.

[65] The flow rate may be greater than substantially 7 m/s, the rotational speed may be greater than substantially 30 rpm and the power may be greater than substantially 1500 W.

[66] According to another aspect, there is provided a turbine comprising at least one blade as described herein.

[67] The turbine may be a helical turbine.

[68] The at least one blade may be three blades.

[69] The at least one blade may be pitched at substantially 60°.

[70] When in a flow rate and rotating at a rotational speed, the turbine may be able to produce greater than a threshold of power.

[71] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 10 rpm and the power may be greater than substantially 40 W.

[72] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 20 rpm and the power may be greater than substantially 100 W.

[73] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 30 rpm and the power may be greater than substantially 160 W.

[74] The flow rate may be greater than substantially 7 m/s, the rotational speed may be greater than substantially 10 rpm and the power may be greater than substantially 450 W.

[75] The flow rate may be greater than substantially 7 m/s, the rotational speed may be greater than substantially 30 rpm and the power may be greater than substantially 1500 W.

[76] According to another aspect, there is provided method of using a vertical axis turbine comprising a blade as described herein.

[77] The method may comprise placing the turbine in a medium having a flow rate such that the turbine rotates at a rotational speed wherein the turbine may be able to produce greater than a threshold of power.

[78] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 10 rpm and the power may be greater than substantially 40 W. [79] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 20 rpm and the power may be greater than substantially 100 W.

[80] The flow rate may be greater than substantially 2 m/s, the rotational speed may be greater than substantially 30 rpm and the power may be greater than substantially 160 W.

[81] The flow rate may be greater than substantially 7 m/s, the rotational speed may be greater than substantially 10 rpm and the power may be greater than substantially 450 W.

[82] The flow rate may be greater than substantially 7 m/s, the rotational speed may be greater than substantially 30 rpm and the power may be greater than substantially 1500 W.

[83] Other aspects of the invention are also disclosed.

Brief Description of the Drawings

[84] Notwithstanding any other forms which may fall within the scope of the present invention, a preferred embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:

[85] Figure 1 shows an outer view of blade for a vertical axis turbine in accordance with a preferred embodiment of the present disclosure;

[86] Figure 2 shows an inner view the blade in accordance with a preferred embodiment of the present disclosure;

[87] Figure 3 shows a trailing view the blade in accordance with a preferred embodiment of the present disclosure;

[88] Figure 4 shows a leading view the blade in accordance with a preferred embodiment of the present disclosure;

[89] Figure 5 shows a superior view the blade in accordance with a preferred embodiment of the present disclosure;

[90] Figure 6 shows an inferior view the blade in accordance with a preferred embodiment of the present disclosure;

[91] Figure 7 shows a perspective view of a vertical axis helical turbine comprising the blade in accordance with a preferred embodiment of the present disclosure;

[92] Figure 8 shows an elevation view of the turbine in accordance with a preferred embodiment of the present disclosure;

[93] Figure 9 shows power output test results comparing a conventional vertical axis helical turbine against the turbine of the present disclosure;

[94] Figure 10 shows various landmarks of the blade in accordance with the Best Mode embodiment of the present disclosure; and [95] Figure 11 shows a graph of the approximate dimensions of the landmarks of Figure 10 in accordance with the Best Mode embodiment of the present disclosure.

Description of Embodiments

[96] For the purposes of promoting an understanding of the principles in accordance with the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the disclosure as illustrated herein, which would normally occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the disclosure.

[97] Before the structures, systems and associated methods relating to the a blade for a vertical axis turbine, a turbine comprising the blade and a method of operation of the turbine are disclosed and described, it is to be understood that this disclosure is not limited to the particular configurations, process steps, and materials disclosed herein as such configurations, process steps, and materials may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the disclosure will be limited only by the claims and equivalents thereof.

[98] In describing and claiming the subject matter of the disclosure, the following terminology will be used in accordance with the definitions set out below.

[99] It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[100] As used herein, the terms "comprising," "including," "containing," "characterised by," and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps.

[101] It should be noted in the following description that like or the same reference numerals in different embodiments denote the same or similar features.

Introduction

[102] In the embodiment that follow, and as is presented in the accompanying drawings, there will be described a blade 100 for a vertical axis turbine and a vertical axis turbine 200 comprising the blade 100.

[103] As will become apparent from the ensuing description, the blade 100 advantageously employs bio-mimicry in substantially mimicking the pectoral fan of a humpback whale. Specifically, the blade 100 is primarily characterised in comprising a tubercled leading-edge 125 which, as can be appreciated from the empirical test data provided below, contributes to increasing the torque produced by the turbine 200 by between 48 and 74%.

[104] The blade 100 further comprises other characteristics enhancing the lift and the like of the blade 100 and therefore increasing the torque produced by the vertical axis turbine 200.

Orientation

[105] Turning now to Figure 1, there is shown and outer view of the tubercled blade 100. For the purposes of orientation, reference will be made to the orientational axes comprising the substantially heightwise superior-inferior axis, breadthwise outer-inner axis and lengthwise leading-trailing axis.

[106] In places, the superior-inferior axis may be referred to interchangeably as the height, the outer-inner axis as the breadth and the leading-trailing axis as the width.

[107] It should be noted that this orientation nomenclature is for orientation description convenience only and no technical limitations should necessarily be imputed to the blade 100 or turbine 200 accordingly.

[108] In this regard, in use, the blade 100 generally travels with the leading-edge 125 forwards, that is, from right to left as is substantially provided in Figure 1.

[109] Furthermore, the blade 100 is generally vertically orientated in the orientation provided in Figure 1 with the inferior portion being beneath the superior portion. However, it should be noted that the blade 1 need not necessarily be orientated in this manner and in embodiments may be orientated upside down also.

[110] Considering the other drawings, whereas Figure 1 shows an outer view of the blade, Figures 2-6 show inner, trailing, leading, superior and inferior respective views.

Blade for a vertical axis turbine

[111] As alluded to above, Figure 1 shows a blade 100 for a vertical axis turbine. In the embodiments described herein, the blade 100 will be described with reference to the blade 100 preferably being employed in a vertical axis turbine and especially a helical vertical axis turbine. However, it should be appreciated that the blade 100 may not necessarily be limited to this particular application and may offer superior performance characteristics for other hitherto untested turbine types including propeller turbine types.

[112] As is apparent from the figure, the blade 100 comprises a tubercled leading-edge 125. Furthermore, the blade 100 is twisted so as to be suited for rotating about the vertical axis of the vertical axis turbine 200 in use, as will be described in further detail below.

Tubercled leading edge

[113] The leading edge 125 comprises a plurality of tubercles 105. [114] As is apparent, the tubercles 105 comprise tubercles 105 of differing prominence. Specifically, the plurality of tubercles 105 comprises widthwise dominant tubercles 105a and widthwise subservient tubercles 105b.

[115] In the embodiment shown, the widthwise subservient tubercles 105b are interposed the widthwise dominant tubercles 105a. Specifically, in the particular embodiment provided in Figure 1, the leading-edge comprises two widthwise dominant tubercles 105a, two widthwise subservient tubercles 105b located between the two widthwise dominant tubercles 105a and a further five widthwise subservient tubercles 105b located beneath the two widthwise dominant tubercles 105a.

[116] It should be noted that while the blade 100 preferably comprises the tubercle 105 configuration as shown in figure 1, variations may be made to the tubercle 105 configuration within the scope of the embodiments described herein.

[117] Reference is also made to figure 4 showing the leading view of the blade 100 showing the arrangement of the tubercles 105 in further detail.

Non-tubercled trailing edge

[118] The blade 100 further comprises a non-tubercled trailing edge 130.

[119] Figure 3 shows the trailing edge 130 in further detail wherein, as is apparent, the trailing edge 130 is devoid of tubercles 105.

[120] Referring again to Figure 1, the trailing edge 130 is substantially non-linear.

[121] Specifically, the non-linear trailing edge 130 comprises an intermediate trailing edge 115b bounded by respectively laterally adjacent superior 115a and inferior 155c trailing edges. The intermediate trailing edge 115b and the superior trailing edge 115a transition at outward junction 110a whereas the intermediate trailing edge 115b and the inferior trailing edge 115c transition at inward junction 110b.

[122] As is also apparent, in one embodiment, the intermediate trailing edge 115b is substantially straight, the superior trailing edge 115a is substantially concave and the inferior trailing edge 115c is substantially convex.

Tubercle foil

[123] Considering specifically now the leading-edge 125 as is shown substantially in figure 4, it is apparent that, in a preferred embodiment, at least a subset of the plurality of tubercles 105 have breadthwise prominence.

[124] Specifically, as is shown, the plurality of tubercles 105 defined breadthwise dominant tubercles 105a and breadthwise subservient tubercles 105b. [125] It should be noted that these breadthwise subservient tubercles 105 may comprise a breadth of no greater than the breadth of the blade 100 or alternatively comprise a breadth between the breadth of the blade 100 and the breadth of the breadthwise dominant tubercles 105a. In this regard also, in less preferred embodiments, the tubercles 105, or subsets thereof, may comprise widthwise or breadthwise prominence only.

[126] In the embodiment shown, the breadthwise dominant tubercles 105a are also the widthwise dominant tubercles 105 described above.

[127] As such, these breadthwise dominant tubercles define a foil having a leading-edge breadth and a respectively narrower trailing edge breadth. In this regard, the foil is preferably tapered.

Helical poise

[128] In embodiments, and as alluded to above, the blade 100 is suited for use in a vertical axis turbine. In this regard, the blade 100 could be employed in a Darrieus turbine wherein the blade 100 as substantially vertically orientated.

[129] However, in a preferred embodiment, including for torque pulse reduction, and as will be described in further detail below with reference to the turbine 200, the blades 100 are adapted for helical poise so as to provide a modified Gorlov turbine.

[130] The blade 100 is adapted for helical poise either by being twisted for helical poise or comprising distal ends adapted for helical poise, or a combination of both.

[131] In a preferred embodiment, the helical poise is a left-handed helical poise. Furthermore, the helical poise is preferably pitched at substantially 60°.

Twist

[132] Referring specifically now to the superior view as substantially shown in Figure 5, in a preferred embodiment, the blade 100 is twisted so as to be suited for rotating about the vertical axis of a vertical axis turbine in use.

[133] In a preferred embodiment, the blade 100 is twisted through an angle 0 of substantially 60°. Such a twist favours a turbine 200 comprising three blades 100.

[134] However, it should be noted that in other embodiments, the blade 100 could be twisted through other angles 0 especially for turbines 200 comprising a differing number of blades 100.

Non-linear Width profile

[135] Referring again to Figure 1, it is apparent that the blade 100, in accordance with a preferred embodiment, defines a non-linear width profile. In other words, the width of the blade 100 changes along the superior-inferior axis. [136] Specifically, the blade 100 defines a superior width 120a and a respectively narrower inferior width 120c.

[137] Furthermore, the blade 100 may define an intermediate width 120b being greater than the supine width 120a and the inferior width 120c.

Dimensions

[138] In a preferred embodiment, the blade 100 is sized and dimensioned for use in a vertical axis helical turbine 200 for placement in flowing water such as rivers, esturies, tidal inlets and the like for the purposes of generating power.

[139] In a yet further preferred embodiment, the blade 100 is sized and dimensioned so as to be able to provide a helical vertical axis turbine 200 providing sufficient torque such that when coupled to an electromechanical generator, is able to provide enough electrical power to boil a litre of water.

Power output test results comparison

[140] The below table shows the power output test results from the above mentioned CSI O report showing the differences in power output between the tubercled blade 100 and conventional blade design:

Table 1 Percentage improvements when compared to conventional hiades

[141] Furthermore figure 9 shows a further comparison from the report showing the differences in power output between the tubercled blade 100 and conventional blade design.

[142] As is apparent from the data, the blade 100, when used in a three blade helical vertical axis turbine 200 and the flow rates of between 2 and 7 m/s is able to produce power output percentage improvements of between 48.9 and 74.7%.

[143] As such, in a preferred embodiment, the blade 100 is dimension such that when used in a three blade vertical axis turbine 200 placed in a flow rate and rotating at a rotational speed, the three blade vertical axis turbine 200 is able to produce greater than a threshold of power.

[144] In one embodiment, the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 40 W. [145] In a further embodiment, the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 20 rpm and the power is greater than substantially 100 W.

[146] In a yet further embodiment the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 160 W.

[147] In another embodiment the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 450 W.

[148] In another embodiment the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 1500 W.

[149] In one particular embodiment, the blade 100 comprises a height of substantially 1 m, a width of substantially .75 m and a breadth of substantially 15 cm.

A vertical axis turbine

[150] Turning now to Figures 7 and 8, there is shown a vertical axis turbine 200 comprising the blade 100 as described above.

[151] Specifically, Figure 7 shows a perspective view of the turbine 200 and Figure 8 shows a side elevation view of the turbine 200.

[152] Referring to Figure 7, in the embodiment shown, the turbine 200 would rotate clockwise such that the blades 100 present a forwards facing tubercled leading edge 125.

[153] In a preferred embodiment, the turbine 200 is a helical vertical axis turbine. However, as alluded to above, in other less preferred embodiments especially on account of torque pulse problems, the turbine 200 could be a non-helical vertical axis turbine. Yet further, and as also alluded to above, in other embodiments, other types of hitherto untested non-vertical axis turbines 200 may employ the blade 100, including propeller turbines such as, for example, for power generation wind turbines or powered boat propeller turbines.

Best Mode

[154] As described above, extensive CFD modelling design adjustments have resulted in the approximate dimensions described in this section as the Best Mode.

[155] Specifically, the best mode dimensions, discovered through the extensive CFD modelling by the Inventor, are provided in the table below, making cross-reference to the landmarks given in Figure 10:

[156] As can be seen from the above table and figure 10, various landmarks have been identified for illustrative purposes. Generally, these landmarks, numbered Z00-Z22 for convenience, define various widthwise profiles of the blade 100 such as the peaks and troughs of the tubercles 105.

[157] Figure 10 shows the exemplary locations of the landmarks for illustrative convenience purposes. It should be noted that the placement of these landmarks is approximately only.

[158] As can be seen from the above table, each landmark may be defined by a percentage length along the length of the blade 100 from 0 to 100%. Alternatively, each landmark may be defined by a percentage twist about the turbine axis from 0 to 60%.

[159] Furthermore, the leading and trailing edges may be defined by x-axis coordinates from 0 to 22 cm.

[160] Specifically, each landmark may be defined by X_start, being the x-coordinate within the local blade plane coordinate system for the start of the trailing edge in cm. Similarly, X_end is for the leading edge in the same plane.

[161] As dimensions may vary, the above table shows the width in centimetres and also in a dimension invariant percentage width from 0 to 100%.

[162] Finally, the t_NAClOTH AI RE55n, been the maximum thickness for a NACA a file profile in centimetres.

[163] Figure 11 shows a graph showing the X_start and X_e„d values, for various twist percentages of the blade from the above table.

Interpretation

Embodiments:

[164] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[165] Similarly it should be appreciated that in the above description of example embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description of Specific Embodiments are hereby expressly incorporated into this Detailed Description of Specific Embodiments, with each claim standing on its own as a separate embodiment of this invention.

[166] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Different Instances of Objects

[167] As used herein, unless otherwise specified the use of the ordinal adjectives "first", "second", "third", etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

Specific Details

[168] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. Terminology

[169] In describing the preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "forward", "rearward", "radially", "peripherally", "upwardly", "downwardly", and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

Comprising and Including

[170] In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

[171] Any one of the terms: including or which includes or that includes as used herein is also an open term that also means including at least the elements/features that follow the term, but not excluding others. Thus, including is synonymous with and means comprising.

Scope of Invention

[172] Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

[173] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Industrial Applicability

[174] It is apparent from the above, that the arrangements described are applicable to the turbine industries.

Claims

1. A blade for a vertical axis turbine, wherein the blade defines:

a tubercled leading edge and a trailing edge; and

is twisted through approximately 60° for rotating about the axis of the turbine in use, wherein the blade defines a series of landmarks, each landmark having:

a twist of plane about the axis of the turbine from 0° to 60°; and

a percentage width of the maximum width of the blade from 0% to 100%, wherein the landmarks (numbered with Z numbering for convenience), comprise:

Z03 having a twist of approximately 18° and a percentage width of approximately 100%; and Z09 having a twist of approximately 36° and a percentage width of approximately 80%.

2. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z00 having a twist of approximately 0° and a percentage width of approximately 60%.

3. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z01 having a twist of approximately 6° and a percentage width of approximately 60%.

4. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z02 having a twist of approximately 12° and a percentage width of approximately 80%.

5. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z04 having a twist of approximately 24° and a percentage width of approximately 84%.

6. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z05 having a twist of approximately 26.4° and a percentage width of approximately 88%.

7. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z06 having a twist of approximately 28.8° and a percentage width of approximately 80%.

8. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z07 having a twist of approximately 31.2° and a percentage width of approximately 82%.

9. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z08 having a twist of approximately 33.6° and a percentage width of approximately 76%.

10. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z10 having a twist of approximately 40.5° and a percentage width of approximately 68%.

11. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Zll having a twist of approximately 43.5° and a percentage width of approximately 64%.

12. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z22 having a twist of approximately 45° and a percentage width of approximately 52%.

13. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z13 having a twist of approximately 46.5° and a percentage width of approximately 48%.

14. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z14 having a twist of approximately 48° and a percentage width of approximately 44%.

15. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z15 having a twist of approximately 49.5° and a percentage width of approximately 40%.

16. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z16 having a twist of approximately 51° and a percentage width of approximately 34%.

17. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z17 having a twist of approximately 52.5° and a percentage width of approximately 36%.

18. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z18 having a twist of approximately 54° and a percentage width of approximately 32%.

19. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z19 having a twist of approximately 55.5° and a percentage width of approximately 32%.

20. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z20 having a twist of approximately 57° and a percentage width of approximately 28%.

21. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z21 having a twist of approximately 58.5° and a percentage width of approximately 28%.

22. A blade as claimed in claim 1, wherein the landmarks further comprise landmark Z22 having a twist of approximately 60° and a percentage width of approximately 24%.

23. A blade as claimed in any one of claims 1 to 22, wherein the blade is dimensioned such that when used in a three-blade vertical axis turbine placed in a flow rate and rotating at a rotational speed, the three blade vertical axis turbine is able to produce greater than a threshold of power. 25. A blade as claimed in claim 23, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 40 W.

25. A blade as claimed in claim 23, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 20 rpm and the power is greater than substantially 100 W.

26. A blade as claimed in claim 23, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 160 W.

27. A blade as claimed in claim 23, wherein the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 450 W. 28. A blade as claimed in claim 23, wherein the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 1500 W.

29. A blade for a vertical axis turbine, wherein the blade defines:

a tubercled leading edge and a trailing edge; and

a twist of plane about the axis of the turbine from 0° to 60°; and

Z00 having a twist of approximately 0° and a percentage width of approximately 60%

Z01 having a twist of approximately 6° and a percentage width of approximately 60%;

Z02 having a twist of approximately 12° and a percentage width of approximately 80%;

Z03 having a twist of approximately 18 land a percentage width of approximately 00%;

Z04 having a twist of approximately 24° and a percentage width of approximately 84%;

Z05 having a twist of approximately 26.4° and a percentage width of approximately 88%;

Z06 having a twist of approximately 28.8° and a percentage width of approximately 80%;

Z07 having a twist of approximately 31.2° and a percentage width of approximately 82%;

Z08 having a twist of approximately 33.6° and a percentage width of approximately 76%;

Z09 having a twist of approximately 36° and a percentage width of approximately 80%;

Z10 having a twist of approximately 40.5° and a percentage width of approximately 68%;

Zll having a twist of approximately 43.5° and a percentage width of approximately 64%;

Z22 having a twist of approximately 45° and a percentage width of approximately 52%;

Z13 having a twist of approximately 46.5° and a percentage width of approximately 48%;

Z14 having a twist of approximately 48° and a percentage width of approximately 44%;

Z15 having a twist of approximately 49.5° and a percentage width of approximately 40%;

Z16 having a twist of approximately 51° and a percentage width of approximately 34%;

Z17 having a twist of approximately 52.5° and a percentage width of approximately 36%;

Z18 having a twist of approximately 54° and a percentage width of approximately 32%;

Z19 having a twist of approximately 55.5° and a percentage width of approximately 32%;

Z20 having a twist of approximately 57° and a percentage width of approximately 28%;

Z21 having a twist of approximately 58.5° and a percentage width of approximately 28%; and

Z22 having a twist of approximately 60° and a percentage width of approximately 24%. 30. A turbine comprising at least one blade is defined in any one of claims 1 to 29.

31. A turbine as claimed in claim 30, wherein the turbine is a helical turbine.

32. A turbine as claimed in claim 31, wherein the at least one blade is three blades.

33. A turbine as claimed in claim 32, wherein the at least one blade is pitched at substantially 60°.

34. A turbine as claimed in claim 32, wherein, when in a flow rate and rotating at a rotational speed, the turbine is able to produce greater than a threshold of power.

35. A turbine as claimed in claim 34, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 40 W.

36. A turbine as claimed in claim 34, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 20 rpm and the power is greater than substantially 100 W.

37. A turbine as claimed in claim 34, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 160 W.

38. A turbine as claimed in claim 34, wherein the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 450 W.

39. A turbine as claimed in claim 34, wherein the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 1500 W.

40. A method of using a vertical axis turbine comprising a blade as defined in any one of claims 1 to 29.

41. A method as claimed in claim 40, wherein the method comprises placing the turbine in a medium having a flow rate such that the turbine rotates at a rotational speed wherein the turbine is able to produce greater than a threshold of power.

42. A method as claimed in claim 41, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 40 W.

43. A method as claimed in claim 41, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 20 rpm and the power is greater than substantially 100 W. 44. A method as claimed in claim 41, wherein the flow rate is greater than substantially 2 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 160 W.

45. A method as claimed in claim 41, wherein the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 10 rpm and the power is greater than substantially 450 W.

46. A method as claimed in claim 41, wherein the flow rate is greater than substantially 7 m/s, the rotational speed is greater than substantially 30 rpm and the power is greater than substantially 1500 W.