DE29617306U1 - Jacketed wind turbine - Google Patents

Description

The invention relates to a counter-rotating ducted wind turbine, consisting of an octagonal, funnel-shaped ring casing (in the inflow and outflow areas) made of aerodynamically shaped wind deflectors, the nozzle-shaped casing of which as a whole forms a turbine-like flow channel.

The accelerated air flow through the jet turbine, forced by the flow, creates kinetic lift on the two rotors (which rotate in opposite directions). In order to ensure a constant speed ratio for the two counter-rotating two-blade rotors, the speed is regulated by an electronic speed controller, which compensates for and adjusts any possible differences in generator output. An optimized speed range of the rotors noticeably increases the overall efficiency of the wind turbine due to the improved flow.

Disadvantages of this design arise when only one rotor rotates in one direction; because the increased swirl formation caused by high speeds of the rotor body means, in terms of flow physics, a reduction in the throughput of the air masses and thus a reduction in the flow speed. The result is a deterioration in the efficiency of the rotor performance.

The object of the invention is to construct an arrangement of the type mentioned at the beginning, which is intended to eliminate the disadvantage described.

The solution to the problem according to the invention consists in providing the wind turbine with a second rotor body (with an opposite direction of rotation in relation to the first rotor body). The opposite arrangement of the two turbine rotors causes a massive reduction in the formation of swirl that reduces performance.

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From the following description and the schematic and
perspective view of the jet wind turbine is intended to
invention will be explained in detail.

ffig.1 : Overall perspective view of the ducted wind turbine;

Fig.2 : Perspective view of the ducted wind turbine with generator/rotor combination;

gig.3 : Front view of the ducted wind turbine;

gig.4· ; Schematic side view of the ducted wind turbine;

As can be seen from the four illustrations, the
Ducted wind turbine consisting of an octagonal, funnel-shaped
Turbine housing.; on the inflow and outflow side in the form of eight fixed wind deflectors 1a,b,c,d,e,f,g,h with proportionally increasing flow cross-section constriction in the inflow area and with the same cross-section expansion in the outflow area. Two permanent magnet generators 2,3 are also installed in the turbine housing. On the two horizontally counter-rotating generator shafts there are two two-blade rotors 4,5" which are aligned fluidically on the windward and leeward sides. The turbine with the generators and rotors
is located on a frame construction 6 with support struts to make the system storm-proof and resistant to tipping. The ducted wind turbine is mounted on a rotating head 7 so that the jet turbine can automatically align itself in the prevailing wind direction.

A round and hollow-profile steel mast gives the overall structure sufficient static bending rigidity.

The turbine ring casing represents a jacketed flow channel consisting of eight fixed guide surfaces with proportional
decreasing V/indführung cross-section constriction in the flow direction of the diffuser. The cross-section

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The aerodynamic consequence of reducing the inflow area is that the air flow is accelerated with a jet effect. The constantly rising convex surface profile of the inner wall of the individual wind deflectors increases the air flow speed. The result, in terms of movement, is a high speed of the turbine rotor, which in turn effectively transfers an increased amount of kinetic energy to the downstream generator shaft.

To increase the overall performance efficiency, a second, counter-rotating turbine rotor (seated on a second generator shaft) is arranged within the jacket nozzle. In the narrowed flow zone of the nozzle, the opposing rotational movements of the two rotors neutralize the formation of swirl, which reduces performance; i.e. the turbine blades are optimally surrounded by the air masses and can flow out through the diffuser in a laminar manner without being swirled too much. The truncated cone-shaped extension of the diffuser creates an artificial negative pressure in the outlet area. The air flowing through can therefore be discharged to the ambient air more quickly.

The fluidic prerequisite for optimizing the flow behavior can only be achieved if the flow channel, from the smallest cross-sectional constriction in the outflow direction of the diffuser, is designed with a maximum expansion angle of 12-15 degrees, otherwise the boundary layer will separate, which can lead to considerable losses (due to turbulence) of the flow energy.

The flow-technically opposing arrangement of the turbine blades in the nozzle-shaped flow zone, in conjunction with the diffuser, results in an almost swirl-free and thus laminar outflow of the air masses from the turbine casing into the ambient air. The formation of a turbulent air flow in the turbine is thus prevented.

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A turbine shutdown is not necessary in terms of fluid mechanics. To ensure optimum generator performance even in storms, the rotor performance can be regulated and limited as follows: The stall effect is used for power control: The rotor blades have a fixed angle of attack, i.e. due to a fixed angle of attack of the blade, the flow behavior of the wing profile deteriorates from a certain wind speed. The result is a stall on the wing profile. This regulates the speed of the rotor and limits the generator performance accordingly. Over-spinning or over-spinning of the power generator is avoided.

The Mastwind turbine is mounted on a rotating head and can be adjusted and aligned in any wind direction. The wind turbine is mounted on the rotating bearing in such a way that the optical symmetry of the turbine is shifted 70% to the side facing away from the wind (seen from the center of gravity of the mast). The increase in the leeward position of the turbine causes passive wind introduction through automatic wind rotation. This automatic wind alignment is achieved by the wind pressure, which - due to the shape of the turbine - causes a stronger damming effect on the leeward-facing surface of the turbine.

The oblique flow generates a dynamic pressure of the wind on the leeward side of the turbine housing, a so-called yaw moment around the wind axis, which automatically turns the turbine like a wind vane in the prevailing wind direction. If the wind turbine is then in an optimal wind position, the accelerating air flow in the annular casing nozzle ensures that the turbine is kept permanently stable in the most favorable inflow position.

Claims (6)

Expectations Counter-rotating ducted wind turbine, consisting of an octagonal ring housing in the form of eight fixed wind deflectors with proportionally increasing flow cross-section constriction on the inflow side and cross-section expansion on the outflow side, and with two generators installed in the housing, the two shafts of which are provided with two two-blade rotors - with opposite rotation - characterized in that 1. Each of the eight wind deflectors (1a,b,c,d,e,f,g,h) together represents a turbine-like casing, the flow deflectors of which have been profiled on the inside with a proportionally extending convex, flow-physical surface profile from the inflow to the outflow side; 2. two permanent magnet generators (2,3") were arranged in the turbine housing; 3. each of the two shafts of the generators (2,3) is provided with two two-blade rotors (4,5) whose direction of rotation is opposite and the flow of the aerodynamically profiled rotor blades (A-,5) occurs on the windward and leeward sides; 4. the turbine housing (1a-h) with the two generators (2,3) was mounted on a frame structure (6) with the help of support struts in a storm-proof and tilt-proof manner; 5. the mantle wind turbine can automatically align itself in any wind direction via a pivot bearing (7); 6. the ducted wind turbine is supported by a round and hollow-section steel mast (8);