NZ264780A - Vertical axis (savonius type) wind rotor: wind passes through duct with s-shaped side portions - Google Patents

Description

-V / 26 4 7 80 NEW ZEALAND PATENTS ACT, 1953 No: 264780 Date: 26 October 1994 COMPLETE SPECIFICATION WIND POWERED APPARATUS I kjah We, ARTHUR JOHN RENDLE, a British subject, of 44 Redwood Avenue, Tawa, _ Wellington; and FRANCIS BRIAN SHORLAND, a New Zealand citizen, of 267 Karaka -| Bay Road, Seatoun, Wellington; both of New Zealand, do hereby declare the invention ~ for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 26 4 7 8 0 This invention relates to a rotor operable in a fluid flow and preferably an airflow to generate mechanical energy.

Wind power principles and their applications are well recognised. One class of rotor used to generate mechanical energy through wind power is commonly identified as a vertical rotor. A vertical rotor may be multidirectional principally relying upon the magnus force to initiate motion. An example of such a rotor is the Savonius wing rotor which is composed of a cylinder split longitudinally and the two sides given relative displacement. The wing rotor could exert large torque at low speeds but had low intrinsic power.

There are many advantages particularly for small domestic installations in the application of an efficient vertical rotor. It has low operating noise and the ability to perform safely at high wind speeds and invariable velocities wind conditions.

We have therefore sought to create a vertically operable rotor which has higher intrinsic efficiency.

Accordingly, the invention may broadly be said to consist in a rotor comprising an S-shaped duct incorporating mounting means to enable symmetrical support on an axis of rotation with the curvature within the duct designed in use for the passage of a fluid through the duct with no or minimum turbulence.

In a further aspect, the invention consists in wind power apparatus including a rotor according to the preceding paragraph.

One preferred form of the invention will now be described with reference to the accompanying drawings in which; Fig. 1 is a plan view of a single duct rotor according to the present invention, Fig. 2 is a side elevation of Fig. 1, Fig. 3 is a diagrammatic plan illustrating the wind path through a wing rotor according to the prior art, Fig. 4 is a diagrammatic illustration of the wind path through the rotor according to the present invention, Fig. 5 is a multi-ducted rotor with the single ducts offset along a single axis of rotation in a spiral formation, 86 A 7 80 Fig. 6 is a'side view of Fig. 5 but with the direction along the axis of rotation significantly compressed, and Fig. 7 is a diagrammatic view of the rotor in application in wind powered apparatus.

The rotor according to die present invention is initially described as a single duct rotor but practically it would be applied as a more complex rotor having a plurality of the single ducts offset one from the other along a common axis of rotation. The single rotor 1 illustrated in Figs. 1 and 2 has generally a shallow S configuration with a central mounting 2 to enable the rotor to be symmetrically supported on an axis of rotation. The duct has openings 3 and 4 at the extremities with curved surfaces 5 and 6 arranged to change the direction of the fluid flow as it passes from one opening to the other. The confining surfaces 7 and 8 complete the duct.

It is important to ensure that the curved surfaces 5 and 6 changing the direction of the fluid flow are not too acute. While the rotor would act in any fluid flow, it is principally designed for use in an airflow and it would be important to ensure that the airflow is not stalled but moves smoothly through the duct without turbulence.

Achieving this type of flow enhances the efficiency by creating a lifting effect as the air passes about the larger curved surface and minimising turbulence as the airflow is discharged through the outlet opening.

The rotor can operate at any angle to the airflow but ordinarily would be arranged on a vertical axis of rotation effectively having the airflow at right angles thereto. The rotor operates with the airflow in either direction and in the complex rotor described here below will operate with an airflow from any direction.

To achieve the maximum efficiency, it is preferable to cause the change in direction of the fluid flow over a flat or substantially flat surface. Thus at least the surfaces 5 and 6 should be flat and from a practical point of view, the duct will be constructed with surfaces 5, 6, 7 and 8 all flat either producing a square or rectangular surface preferably with the width of the surfaces 5 and 6 substantially the same as or greater than the width of the surfaces 7 and 8. 26 4 7 8 0 The impact on fluici flow is diagrammatically illustrated in Figs. 3 and 4. Fig. 3 represents the air movement through the wing rotor according to the prior art. At the sharp bridge generated at 9 and 10 in the wing rotor, there is considerable turbulence induced that reduces the efficiency in the rotor and leads to its lower intrinsic power. On the other hand in the duct according to the present invention illustrated in Fig. 4, the fluid flow preferably an airflow passes from the inlet 3 to the outlet 4 with no or minimum turbulence and because of the smooth airflow, is able to create an increased power output.

While the single rotor illustrates the principal of the invention for this principal to be reduced to practical effect, a more complex rotor will be required. The complex rotor is produced by arranging a plurality of the single rotors on a common axis of rotation. A preferred configuration is illustrated in Fig. 5 where a plurality of single ducts are offset to create a spiral formation along the axis of rotation with each duct arranged at an angle of substantially 30° to the other so that the six ducts complete an evenly foimed spiral. The six ducts are identified with letters A to F, and these are shown also in Fig. 6 although for space, the distance along the axis of rotation has been significantly compressed.

The rotor according to the present invention may have application in other fluid flows but it is principally designed for use as a rotor in wind generating apparatus and this apparatus is diagrammatically illustrated in Fig. 6. The complex rotor 11 is supported on a shaft 12 that is mounted on a top bearing block 13 designed to support the weight of the rotor and a lower locating bearing block 14. The shaft ha- a take off pulley 15 with a belt drive 16 to a pulley 17 driving a shaft 18 connected to a transmission 19 which in turn is connected to a generating unit 20 produce a power output at 21. This equipment will, of course, be appropriately located in a suitable structure and housing, and controlled to achieve the outputs desired in accordance with technology that is well recognised by those skilled in the art.

In the present invention, different configurations of complex rotors can be produced, and the duct section varied. The duct curvature can be optimised by mounting opposing ducts on a single axis of rotation. The more efficient duct will dominate and allow by reasonable experimentation the most effective parameters to be selected using the teaching of the present invention.

An operating model of the complex rotor in wind generating apparatus has been mounted to operate 4m above ground level. The six ducts as described above are offset at 30° to 264780 each other in spiral formation. Each duct is 1.2m long from tip to tip to describe a circle of 1.2m diameter when turning. Wind conditions experienced at the site of installation have been variable with the typography to cause violent fluctuations in the wind n locity. A typical example would be for the velocity to vary from 3m per second to 13 n per second every 10 to 15 seconds. During the operation, lower velocities excsede i higher velocities even in these conditions very encouraging power output resuhs have been achieved. Also, this efficiency has been achieved with a relatively noiseless operation of the rotor and with the rotor able to function at higher wind velocities • San would be acceptable with more conventional wind generating rotors.

Claims (11)

WHAT WE CLAIM IS: - 6- 264780

1. A rotor comprising an S-shaped duct formed by two S-shaped side wall said duct incorporating mounting means to enable symmetrical support on an axis of rotation with the curvature within the duct designed in use for the passage of a fluid through the duct with no or minimum turbulence.

2. A rotor as claimed in claim 1 wherein the cross-sectional shape of the duct is regular and selected to enhance a substantially turbulence free flow of fluid directed through the duct.

3. A rotor as claimed in claim 2 wherein the duct has flat or substantially flat surfaces in the curved faces of the S duct changing the direction of the fluid flow.

4. A rotor as claimed in claim 3 wherein the distance acrosr. the curved surfaces changing the fluid flow in the duct is greater than the distance between the confining walls adjoining such surfaces.

5. A rotor as claimed in any one of the preceding claims having a plurality of ducts arranged offset one from the other about the same axis of rotation.

6. A rotor as claimed in claim 5 wherein the plurality of ducts are offset to create a helical formation along the axis of rotation.

7. A rotor as claimed in claim 6 wherein six rotors offset substantially 30° one to other create the completed helical rotor.

8. A rotor when constructed arranged and operable substantially as herein described with reference to Figs. 1 and 2 and 4 to 7 of the accompanying drawings.

9. Wind powered apparatus including a rotor according to any one of the preceding claims.

10. Wind powered apparatus..accordu^-to^a|gH9-|including transmission, generation and control means to convert thi^echamcal-enefgy- created by the rotor into electrical energy. J ~ 3 JUL "1997 'i-r' Ixio 264766 -7- — I

11. Wind powered apparatus when constructed arranged and operable substantially as herein described with reference to Figs. 1 and 2 and 4 to 7 of the accompanying drawings. DATED THIS 1&**1 DAY OF J a* 19 % A. J. PARK & SON if mi* PER AGENTfe FOR THE APPLICANTS £1® OF* ClAWS