DE102013016085A1 - Slit turbine for generating energy at waterfalls in the small power range - Google Patents

Abstract

The water velocity from the drop height and the amount of water according to Bernoulli give a defined area size for the flow (6). The water velocity and the speed of a propeller blade (15) form the tangential angle of attack. For this angle of attack, the propeller blade (15) must be turned on. The employment of propeller blades (15) changes by the given design along the radius of very steep to flat. If one forms the surface for the flow (6) as an annular opening, ie as a slot (2), this slot (2) can be arranged so that the mechanical angle of attack of the propeller blade (15) and the tangential angle of attack from the speed of the flowing through water and the speed of the propeller blade under the slot form the best working angle for power extraction.

Description

State of the art

There are turbines for the utilization of hydropower in very different designs. A good overview is shown in Figure 1 from Regenerative Energy Systems, Quaschning, Volker.

The white spot in the low power area is the area that is not usually covered by the turbines.

This used to be the area of the waterwheel. Used as a mill drive, the requirement was: slow running with high torque.

These requirements require very expensive construction methods.

With the introduction of electric drives, water wheels became unprofitable.

The attempt to build the large turbines in small dimensions, has failed the cost. However, you can even visit pelton wheels in old mills at about 2 m drop height.

In a special turbine for the small power range has the problem that height and amount of water are each different.

In addition, small power means little return and thus low investment opportunities. Virtually every turbine of the dimensions is a unique piece.

As a business solution remains only a modular system, variably adaptable to fall height, amount of water and the spatial Vorauesstzungen.

task

With the present invention, the aim is to use the water at a barrage or at a mill weir for energy.

The requirement is to find a basic turbine shape that can be adapted to the height of fall and the amount of water.

The production cost must be in reasonable proportion to the yield.

The turbine must be easily and inexpensively installed or installed at very different local conditions.

The drop height is fixed by the local conditions.

The amount of water is subject to natural fluctuations over the course of the year.

solution

To achieve the above object, the invention specified in the characterizing part of claim invention is proposed.

Explanation of the invention

An amount of water flows through an area depending on the flow rate.

A free falling amount of water is accelerated by the attraction and the speed increases with the fall height. This reduces the size of the area through which it flows.

The dependence between velocity and surface area is formulated as a physical law by Bernoulli.

With this relationship, you can calculate the area required for the flow in the turbine for each amount of water and drop height.

This surface can be formed as an annular opening, ie as a slot.

For a given area, the radius determines the slot width.

The radius of the slot determines the speed of the propeller blade under the slot.

From the speed of the water and the speed of the propeller blade below the slot, the local speed of operation and the tangential angle of attack under the slot are calculated.

Each blade of a propeller needs certain basic forms of strength.

This results in the design of a changing angular position of the propeller blade to the tangent along the radius.

With a small radius, the employment is strong, with a larger radius, the angle of attack of the propeller blade becomes flatter.

The speed of the propeller gives the basic measure of the blade speed.

From speed and radius then results in the local blade speed. It has its minimum at the axle and the maximum at the blade tips.

The speed of the water and the speed of the propeller blade at a defined point give the tangential angle of attack.

At this angle of attack, the propeller blade must be in the proper position for good performance.

For the angle of attack so the appropriate angle must be assigned by the choice of the slot radius.

This selection determines the arrangement, i. H. the mean radius of the slot.

The water speed depends only on the height of the fall and is always the same in the turbine.

Although the slit surface in the turbine is just right for one volume of water, smaller amounts of water are practically the same speed, and so the angles fit in the design.

If the amount of water z. B. is significantly less in the summer over a longer period, an adjustment may be necessary.

As soon as the water in the slit is mainly distributed in drops, there is no real flow on the propeller blade and the efficiency drops very sharply.

In such an egesetztetzten system, it may be appropriate to provide the slot narrowings interchangeable to adjust the slot width to the amount of water.

From the above considerations, it follows that the flow in the turbine must be directed into a slot between an inner and an outer tube exactly to the optimum operating point of the propeller blades.

The unaffected parts of the propeller blades theoretically rotate in free space.

It is ideal if pipe widths to DIN fit exactly as inner and outer pipe.

In practice, however, you have two options for correction.

It can be attached to the inner and outer tube or wedge-shaped elements as a slot narrowing to reduce the slot, which impede the flow only insignificantly.

There are also propellers, where the leaves are attached individually.

The attachment then makes the blade adjustment by a few degrees possible.

This is then a fixed position, matching the case height and is not changed in the Betrib.

This allows a turbine over the Anströmschlitz be designed in a wide range exactly.

To integrate a generator, there is no room for this type of turbine.

From the turbine so an axis must be guided to the generator. This gives the possibility for easy adaptation of the generator in stages of construction according to speed and power.

Ideal as a generator is a mains-driven asynchronous machine, because it has a very soft characteristic in the synchronous range and depending on the number of poles predetermined speeds.

This machine is available in the appropriate power ranges, and there are capacitors for reactive power when it is necessary for the grid.

For an island operation other load rules would have to be defined, because unloaded increases the speed of the turbine until the working angle no longer fit.

Image 1

• shows a diagram from the book Regenerative Energiesysteme (L1).

You can see the working areas of the turbines currently used and, as a white tip, the area in which the slitting turbine can work.

picture 2

• shows a propeller ( 1 ) from a catalog for marine propulsion (L2).

The slits are marked ( 2 ) for the smallest drop height ( 4 ) and the largest drop height ( 3 ).

The speed of the generator ( 14 ) is the same.

If these limits are exceeded, then another generator speed must be selected.

Each slot ( 2 ) then moves to another position and then has a different radius and a different width, but the same area.

As an alternative, a propeller remains within a narrow range ( 1 ) with mechanical blade adjustment or a propeller ( 1 ) with a different design, ie with a different mechanical adjustment against the tangent.

picture 3

• shows in section the essential elements of the turbine.

The turbine inlet ( 6 ) is annularly divided into a slot ( 2 ).

A short straight inflow section ( 11 ) gives a uniform flow.

The slot ( 2 ) is here by an outer ring as a slot narrowing ( 10 ) narrows slightly and positions the flow with it.

In the propeller housing ( 12 ) it can be seen that slot ( 2 ) and propellers ( 1 ) have different sizes.

The turbine outlet ( 7 ) is open over a large area, so that the slot ( 2 ) in all sizes and locations of the turbine outlet ( 7 ) is not affected.

An axis ( 5 ) leads to the generator ( 14 ) through the inner tube ( 9 ). So does the rotation ( 13 ) of the axis ( 5 ) the inflow ( 6 ) in the slot ( 2 ) Not.

Because the generator ( 14 ) is arranged outside the turbine, it has no influence on the turbine design.

Due to this modular construction and with an appropriate assembly platform, the turbine can also be installed in a narrow space and without any local construction work.

On a longer, free-standing framework, z. B. a ladder, then water inlet, downpipes as inflow ( 6 ), Turbine and generator ( 14 ) are attached as individual elements.

LIST OF REFERENCE NUMBERS

1

propeller

2

slot

3

Slot largest drop height, off-axis slot

4

Slot smallest drop height, near-axis slot

5

axis

6

Inflow

7

outlet

8th

outer tube

9

inner tube

10

slit throat

11

Einströmstrecke

12

propeller housing

13

direction of rotation

14

generator

15

propeller blade

bibliography

• L1 Regenerative Energy Systems, Quaschning, Volker, 978.3.446-43526.1
• L2 allpa marine equipment catalog 2012

Claims (1)

Slit turbine, characterized in that a calculated from Bernoulli amount of water and drop height as slot area or annular opening is arranged at a distance from the axis, that the speed of the flowing water and the speed of the propeller blade under the slot form the tangential angle of attack, the design-related tangential angle of attack of the rotating propeller blade under the slot gives the working angle necessary for optimum performance.

Images