AU2005224278A2 - Turbine and rotor therefor - Google Patents

Description

AUSTRALIA

Patents act 1990 COMPLETE SPECIFICATION STANDARD PATENT TURBINE AND ROTOR THEREFOR Technical Category: Mechanical, Electrical and electronics.

The following statement is a full description of this invention including the best method of performing it known to me.

TURBINE AND ROTOR THEREFOR OFIELD OF INVENTION This invention relates to a turbine and rotor with an axis of rotation substansially parallel to a gas fluid flow. More particularly, this invention relates to an un-enclosed wind turbine or a rotor impellor that may extract convert energy from to a moving stream of gas or fluid.

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BACKGROUND

SOn the most part, modern wind turbine rotors are of low solidity and have few long W straight blades of airfoil" section revolving around a central horizontal axis with a large proportion of their blade areas situated within the inner half of their diameters.

The very high tip speed ratios involved in obtaining maximum efficiency can greatly add V' to noisy operating conditions of these turbines.

The present inventor has realised that the outer onethird of any turbine rotor does most of the useful work in converting the kinetic energy from a moving gas fluid flow into available torque as torque is a fuction of force x radius, and also that it is more benficial in power production to have an increased gas fluid flow velocity rather than having an increase in the overall size of the turbine rotor, the present invention seeks to situate the majority of the working surface being presented to the gas fluid flow in this outer region in an effort to achieve a high mechanical efficiency within a design that remains relatively basic, un-encumbered, free flowing and does not rely on high tip speed ratios The maximum theoretical percentage of energy that can be extracted from a wind flow is 59.3 (the BETZ limit) and this invention has shown University supervised wind tunnel test results supporting of a maximum co-efficient of power above 52 STATEMENT OF THE INVENTION This invention seeks to provide a high efficiency output from any wind water, steam or gas turbines that have a rotation axis generally parallel to fluid gas flow by using a rotor design that increases through flow velocity by having a total flow outlet area formed by the gaps or voids between its blades vanes much greater than the inlet flow area pre determined by the maximum rotor diameter and also situating the majority of the working suface area in its outer extremities maximising total power output for its size, and comprises of a central hub or shaft rotatable about an axis substansially parallel to gas fluid flow supporting a plurality of integral blade vane units equi-distant and radially arranged around the said hub or shaft that each contains within, an integrally formed combination of typically short inner blade or "wing portions extending substansially outwards from the said hub or shaft and a substansially frontwardly extending outer "vane" section joined to the outer, frontward extremity of the said inner portion with the total vane blade unit being mounted onto the hub shaft so as to form a helix or pitch angle between its outer radial extremities and the said hub shaft axis centre line preferably between 0 6 degrees more than the resultant angle corresponding to the sum of the incoming gas fluid flow vector and the tangental gas fluid "headwind" component due to rotation the complete revolving rotor assembly encouraging the flow from being generally parallel to its axis to moving outwardly and rearwardly in an increasing helical" path preferably exitting in most part past the frontwardly projecting outer vane sections that preferably contain within each, an appropiate angle of incedence at any section along their longitudal axis, to the fluid/ gas flowing past that same specific section irrespective of its cross section.

0 As each blade/ vane unit is preferably balanced both in weight distribution and twisting (moment)forces due to "lift" from fluid/gas flow about its own central mounting point centerline normal to the hub or shaft, there is less or no need for an annular stiffening rim at its forwardmost perimeter or midsection connecting it to other blade/ vane unit Is, which simplifies manufacturability whilst retaining the ability to operate at much higher angular velocities as could otherwise have been been expected without excessive flexing or failure due to large bending or twist stress levels and this design also retains the 00 possibility of the inclusion of blade vane articulation to a differing "attack "angle for the purpose of speed limiting or start up situations In one form of this invention, slightly curved slots have been positioned in the outer rearward ends of the outer portions or vanes extending approximately perpendicular to the "resultant" flow in this region resembling in cross- section a "slotted wing" 0 greatly increasing the lift forces in this said region enabling the rearmost end of the Sblade I vane unit to oppose and balance large moment forces formed by the use of (N 15 extraordinarily pronounced forward projecting vane portions and if desired, to completely overcome these forces and twist the vane section to a lesser helix or "attack angle" feathering the vane further into the incoming flow enabling maximum speed limiting at a predetermined flow velocity.

To assist with understanding the invention, reference will be made to the accompaning drawings which show details of some examples of this invention however it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting the scope of the invention.

In the the drawings: Figure 1 shows a top view of the preferred embodiment.

Figure 2 shows the frontal view of the preferred embodiment and 2 being the direction of rotation in this instance.

Figure 3a 3b and Figure 4 shows various section cutaway views of the preferred integral blade vane unit with Figure 3 b also showing the preferred cross section in the vicintity of slot Figure 5 is an isometric view of the preferred embodiment.

Figure 6 A depicts a simplified multistage turbine embodiment having a second stage with a differing angle of attack and direction of rotation than the first stage to maximise resultant lift forces directed into torque at the hub.

Figure 6 B shows a method of achieving blade angle of attack adjustment with a mounting shaft protruding from the lower central mounting line 8 of the blade vane units which can be articulated by mechanical means built into the hub Figure 6 C shows an embodiment without slots, that also has an annular rim attached to the forwardmost perimeter of the blade vane units to increase rigidity.

Figure 6 D depicts a simplified 2 stage fan that may be enclosed in a duct to suit air craft I hovercraft that has a second rotor with a differing rotation direction and blade pitch angle so as to enable the flow produced by rotation to exit at a typically lesser angle.

Figure 7 shows a face on view of a blade vane unit, where maximum rotor diameter CL max the maximum lift co-efficient for a blade or wing unit area Y the total area of blade vane rearwards of the central mounting point line 8 X the total area of blade vane forward of the central mounting point line 8 A in area of flow intake rotor radius squared x phi. A circ area of flow exitting outwards at perimeter of vanes.

A thru area of flow exitting at rear of rotor 6 pitch or attack angle of blade vane units to the hub shaft axis S* the angle between the vanes leading edge 7 to the hub shaft axis #6.

the angle between the blade section leading edge to the central line 8 1 outer vane section 2 direction of rotation 3 inner blade section 6 hub shaft axis centerline 7 leading edge of vane 8 the central line passing through the centroid of areas #10 perpendicular to the hub or shaft axis.

9 the area of junction between the blade/vane and the central hub or shaft 10 the centroid of area about which the total sum areas of the blade and vane sections are considered to be centered upon 11 the actual "Resultant" flow.

12 the incoming flow direction 14 the angle between the vane blade outer trailing edge and the hub shaft axis.

15 rearward inclination of inner blade or wing section.

Figure 8 is the conclusional page to a University supervised wind tunnel test on a 765 mm Dia. rotor.

Referring to figure 1, A plurality of eqi-spaced integrally formed crooked blade vane units that consist of most _preferably an inner airfoil section blade 3 that extends substansially outwards radially from a central hub or shaft 4 at a slight rearward angle, each inner blade having a leading edge also rearwardly sloping between 5 and 60 degrees from normal and a substansially frontwardly protruding vane section 1 integrally formed with and joined to its outer frontward edge and the whole blade vane unit generally twisted in a helix or pitch angle about the hub /shaft central axis 6 that is preferably parallel to the gas fluid flow direction 12 so as to maximise the lift or deflection forces obtained from the resultant flow and converted into available torque.

rl The vane section 1 is preferable of an air foil cross section that diminishes in chord length in proportion to its distanqp away from the inner blade section 3 to form a curved outer 0 point leading into the oncoming flow.

Referring to Figure 7 The vanes 1 preferably contain slot /s 5 within their outer rear section that are set approximately normal to the resultant flow 11 past that same said section and may be curved each slot being quite narrow with a smoothly rounded exit edges so; as to direct a portion of the gas fluid flow through to the rearward face of the vane blade unit providing an increase of lift' forces in this region Figure 3 b and most preferably forming a secondary "curved "or airfoil cross section in this area and enabling a large increase in the co-efficient of lift in this rearmost vane area being useful in balancing a pronounced front section of vane area having a lesser co-efficient of lift per unit area which can allow for equilibrium to be maintained due to moment or twisting forces about the central line 8 passing through the total vane blade area centroid 10 normal to the hub axis 6.

Also, preferably, the total mass foward of the central line 8 area x -x is equal to the total mass rear of the central line 8 area y y) enabling a fully balanced blade design to be achieved as the central line 8 passes through the centriod of area 10 perpendicular to the hub axis centerline#6 The central hub 4 could be constructed in a variety of shapes and sizes but preferably has a diameter of between 0.2 and 0.4 of the total rotor diameter increasing in diameter in a smoothly curved cone shape towards its rear helping to direct flow outwards and rearwards without imparting excessive turbulence and providing a possible housing for blade articulation mechanisms, a generating unit or connection to a suitable output shaft and I or support bearings.

It can be seen from Figure 1 that the general shape of the complete rotor is designed to to impart a fluid or gas flow pattern that has a substansial outward direction as it moves further into and completely through the rotor As the total exitting flow area A thru plus" A Circ" is much larger than the total inlet flow area A In" with Volume in being equal to Volume out and Volume equal to velocity x area then it follows that from Bemuilies principle that there must be an increase in velocity inside I frontward of the rotor or a pressure drop outside rearward of the rotor all of which improving turbine rotor performance over prior art.

All the leading edges are preferably suitably rounded to minimise turbulence and a good surface finish is applied to all sections with the inner blade section being of sufficient strength to adequately transform or direct the sum of the deflection and "lift" forces from the blades, vanes and slots due to. fluid/ gas flow into torque at the hub or shaft and to be able to withstand centrifugal and bending forces due to the total mass revolving at the maximum rated speed in extreme conditions.

Claims (10)

1. 3. A turbine or rotor as claimed in claim 1 that has its integral blade vane units balanced both in weight distribution about a central line passing through their centroid perpendicular to the hub shaft axis and also the sum of moment or twist forces formed by lift or deflection forces about either side of the same said central line equal until an unbalanced situation is desired to come into effect above a given flow velocity thereby giving rise to rotational speed control.
2. 4. A turbine or rotor as claimed in claim 1 with the majority of cross sectional profiles of each specific cross sectional area of its said integral blade and vane units set at an angle of incedence of between 0 and 35 degrees from gas fluid flow past that said specific area irrespective of their cross sections or dimensions at the same specific area. A turbine or rotor with its integral "blades vanes" as in claim 1 radially displaced around a hub or shaft in an adjustable helix or pitch angle and may be articulated about their individual mounting point central lines( 8) onto the hub shaft to such an extent as to enable "speed limiting" or benefitting start up "conditions.
3. 6. A turbine or rotor with blades and vanes as claimed in claim 1 that may contain there- in one or more narrow "slots" that have at their respective rearward exits a curve radius or air -foil section also having its own incedance angle to flow, in an effort to add to the maximum lift" forces in the vicinity of the specific areas of the vane blades where they are situated.
4. 7. A rotor as claimed in claim 1 that has on its said blade vane units, a convex or air foil surface generally facing opposite the direction of rotation such that when a torque is applied in the direction of rotation as claimed in claim 1, a gas fluid flow may be imparted in the outwardly and rearwardly (toward flow exit) direction.
5. 8. A turbine or rotor as claimed in claim 1 that has the greatest proportion of its vane/ blade surface area situated between 0.3 and 0.5 of the diameter radially from the central axis of rotation.
6. 9. A turbine or rotor as claimed in claim 1 that may be used in an inline or axial multy -rotor turbine arrangement irrespective of whether the said turbine /rotor Is are revolving on the same shaft, hub or in the same direction. turbine or rotor as claimed in claim 7 that may be used in an inline or axial multy -rotor/ turbine arrangement irrespective of whether the said turbines/ rotor/s are revolving in the same direction or on the same shaft hub. NO 6
7. 11. A turbine or rotor as claimed in claim 1 that includes an annular stiffening rim joined to the blade vane sections as herin described in Figure 6c and the Statement description of the invention 00 12. A turbine or rotor as claimed in claim 6 that includes an annular stiffening rim joined (Ni to the blade vane section as herin described in Figure 6c and the Statement/ description of the invention.
8. 13. A turbine or rotor as claimed in claim 7 that includes an annular stiffening rim joined V) to the blade vane section as herin described in Figure 6c and the Statement 0 description of the invention.
9. 14. A turbine or rotor as herin before described with references to Figure 1 through to Figure 7 of the accompaning drawings Frank Daniel Lotrionte
10. 30-11-2006