AU2019100563A4

AU2019100563A4 - Method for manufacturing light weight modular blade for savonius vertical wind turbine using metal sheet and metal pipe

Info

Publication number: AU2019100563A4
Application number: AU2019100563A
Authority: AU
Inventors: Samin Ishraq Siddiquee; Mohammad Rajib Uddin
Original assignee: Uddin Mohammad Rajib Mr; Siddiquee Samin Ishraq Mr
Current assignee: Uddin Mohammad Rajib Mr; Siddiquee Samin Ishraq Mr
Priority date: 2019-05-28
Filing date: 2019-05-28
Publication date: 2019-06-27
Anticipated expiration: 2027-05-28

Abstract

Wind turbine blades need to be light, and strong. Modern blade manufacturing relies on advanced plastics, carbon fiber, or fiber glass, or Fiber-reinforced plastic (FRP). These are used due to their light weight properties, and strength. However, the use of plastics poses problems, such as high cost, requirement for complicated processes and machinery, chemical and vacuum treatments, as well as heat treatment. Metal blade manufacturing has not received success commercially, due to the fact that when compared to a plastic/fiber blade, a metal blade with the same equivalent strength becomes quite heavier, requiring higher wind speeds to start. We have invented a new method for manufacturing light weight modular blades for Savonius type vertical wind turbines using metal sheet and metal pipe. The new method results in a blade that is light weight, strong, and without radial ribs along intervals of the blade. The main feature of the blade is that since it is modular, and can be stacked vertically with other blades and bolted to get a single large blade. As a result, there is no need to produce large single blades for large turbines.

Description

COMPLETE SPECIFICATION

INNOVATION PATENT

METHOD FOR MANUFACTURING LIGHTWEIGHT MODULAR BLADE FOR SAVONIUS VERTICAL WIND TURBINE USING METAL SHEET AND METAL PIPE

The following statement is a full description of this invention, including the best method of performing it known to us:

2019100563 28 May 2019

A vertical wind turbine is a machine that converts kinetic wind energy into rotational mechanical energy, which may be used for generating electricity by driving a permanent magnet generator. There are various types of vertical wind turbine, but one of the earliest designs was the Savonius Vertical Wind Turbine. The Savonius wind turbine functions by capturing the motion of the wind using multiple directional blades, shaped as scoops.

.0 The design of the Savonius effectively makes it a ‘Drag Type’ wind turbine, which rotates at the speed of the wind, and never exceeding it. The most important part of the wind turbine is the blade. The Savonius may have 2, 3 or more blades. The blade is also one of the main cost drivers in wind turbine manufacturing. Traditionally, blades are made from carbon fiber, or fiber glass, or Fiber-reinforced plastic (FRP), or other composites.

.5 The design and manufacturing of blades is a complex process, as it requires a tradeoff between weight and strength. A blade must be light enough to be moved by the wind, but strong enough to resist very strong forces during a storm. The lighter the wind turbine blade, the lower its inertia, and the easier it is for it to rotate with the wind. Hence, light weight plastics are used for constructing blades.

Ό However, plastic blades are very expensive to build, are not environmentally friendly, require complex manufacturing techniques, and require huge energy input during manufacturing, for instance during curing in autoclave. Plastic blades are also not feasible for developing countries for the same reasons. Metal blade production offers a respite from these barriers presented by plastic blade manufacturing.

The use of metal however creates a problem of weight, as metal is heavier than plastic. Welding also adds weight, as well as reducing precision (and thereby increasing deviation). Although purely metal blades have been commercialized, they are not modular and don’t allow stacking without gap. Additionally, current designs result in an overall

2019100563 28 May 2019 turbine that has a high start-up wind speed requirement. Hence, they are disqualified from io use in low wind speed areas/countries.

We have invented a new method for manufacturing a rectangular blade for Savonius vertical wind turbine using metal sheet and metal pipe. The blade is modular, meaning they can be connected to each other to increase blade length. The new method does not require any plastics whatsoever. The new metal blade is light weight and can operate in >5 low wind speeds as low as 1.1 m/s.

The blade is assembled from two manufactured sub-components: a single piece of rectangular metal sheet and a metal frame that runs continuously along the perimeter of the sheet. The frame consists of two semi-circular horizontal crosspieces (4, 5) of equal length, and two straight vertical pieces (6, 7), of equal length as shown in Figure 2. The io two vertical pieces run parallel and attach to each end of the semi-circles, forming 90 degree angles. Parts 4, 5, 6 and 7 together form a continuously running frame (Figure 2).

The wind catching surface of the blade is formed of a rectangular metal sheet (1) drawn over the frame, and attached solidly. This results in a blade with a concave shape on the inside (Figure 1), and a convex shape on the outside (figure 2). The frame is only visible 15 on the inner side (or concave side) of the blade, as shown in Figure 2. Dark continuous line along perimeter of the frame represents the pipe frame, Figure 2. The frame is not visible on the convex side, as shown in figure 1.

The blade also has drilled flat plates attached to the frame (2, 3) as shown in Figure 1.

These enable individual blades (14, 15) to be bolted to each other longitudinally (stacked so vertically) as demonstrated in Figure 3. The blades are bolted using the aligning flat plates at points 11 and 12, as shown in Figure 3. Points 9 and 10 show exposed flat drilled plates that can be used to add more blades longitudinally to the existing stack. Thus the blade assembly can be elongated into one single structure using these modular blades.

The junction where the blades are connected has no gap, as shown in Point 13, Figure 55 3. This results in a 100% metal blade that does not use ribs or any other support within the blade structure, other than along the perimeter. This greatly increases aerodynamic

2019100563 28 May 2019 performance. Other blades use ribs along the entire width of the blade to add strength.

That reduces aerodynamic properties and increases weight.

Increasing the wind contact surface area is an important aspect of wind turbine scalability, io If more power needs to be generated, then more wind contact surface area needs to be available. However, increasing wind contact surface area usually means increasing the size of the blade to get a single continuous running structure. Increasing the size of the blade is expensive, both in terms of manufacturing and also in terms of installation. The new method of manufacturing the blade presented by us here allows for increasing the >5 blade size of a Savonius vertical wind turbine by longitudinally stacking numerous small modular blades together without any gap in between blade joints.

The new method makes manufacturing of a large turbine blade easier, as it does not require a large single blade to be manufactured at once. This means a reduced factory space requirement. Additionally, transportation and logistics is both easier and cheaper Ό as well. Installation is easier, as smaller parts are easier to handle. Maintenance and Repair is also easier with this type of blade. This is because, if there is any damage to a certain part of the blade, only that part can be removed and replaced. Thus reducing cost and burden again.

The new method of manufacturing the vertical wind turbine blade is positively beneficial '5 for the following reasons:

• The new blade allows vertical stacking, thus enabling to assemble one large blade from numerous small modular blades.

• The new method reduces manufacturing cost per blade • The new method does not require expensive Plastics/Polymers, only lightweight so metal is used.

• The new method does not require specialized blade manufacturing machines • The new method does not involve heat/pressure/vacuum treatment • The new method does not require chemical, resin/hardener treatment.

• The new method creates a product that is 100% recyclable

Claims

The claims defining the invention are as follows:

1. We lay claim to the method of manufacturing a modular Savonius vertical wind turbine blade that is made using sheet metal curved into a half-tube and reinforced using a metal perimeter frame. The metal perimeter frame runs along the perimeter of the inner concave side of the half-tube, and is without any ribs or other diagonal or radial strengthening structures. Frame is invisible on convex side of half-tube.
2. We lay claim to the method of increasing vertical wind turbine blade length by longitudinally stacking individual modular blades to form one large blade, without any gap. This invention allows a method to form one large single blade without any gap, by vertically stacking two or more modular blades. These stacked blades are connected to the same drive shaft. The blades are stacked and bolted to each other using aligning flat plates at the end of the blades with holes drilled into them for bolting with other blade plates.