VERTICAL AXIS WIND TURBINE

This invention relates to wind power engineering, namely to rotary wind motors which may be used in wind electrical generators or equipments for conversion of wind energy into electrical energy.

Rotor of prior art for wind motor is known from Russian Federation patent application No. 2135824, IPC⁶ F03D7/06, filing date 09.10.1996, publication date 27.08.1999. Known rotor of wind motor comprises two S-shaped blades mounted on vertical shaft. S-shaped blades are fastened on rotatable paralel cross-arms which are rigidly connected with vertical shaft. Moreover the fastening points of blades are aligned with the axis of symmetry of the blade behind of its centre of gravity in direction away from the vertex of the S-shaped blade.

A disadvantage of the above described known rotary wind motor resides in the complexity of rotary design, low power range and relatively low efficiency.

Another rotary wind motor with vertically positioned shaft is known, e.g., from Russian Federation patent application No. 2096259, IPC⁶ B63H13/00, filing date 15.11.1993, publication date 20.11.1997 (prototype), which is provided with lower and upper disc type washers and mechanism for rotating of blades. Axis of washers is aligned with vertical axis of rotation. On lower end faces of blades there are fastened position locators with possibility to engage them with holes made in said washers. The said mechanism for rotating of blades comprises an element, which is fixed to the rotor shaft, situated on lower washer.

A disadvantage of the said known rotary wind motor resides in insufficient reliability, insuficient power range and insufficiently high efficiency.

An object of the present invention is to increase efficiency and power owing to provision of high rotation speed of rotor and to improve starting acceleration of the rotor.

According to the present invention there is provided a rotary wind motor which comp rises rotor with power elements, e. g., in the form of blades fixed to the vertical shaft, characterized by that the power element is realized in the form of aerodynamic cascade block arranged in turbine type configuration of blades in cascade, mainly in the form of two symmetrically positioned blocks of aerodynamic blades containing four 5 blades in each row

It is advisable to realize cascaded blades in the form of subsonic aerodynamic blades Moreover, it is advisable to have the values of parameters of blades in turbine-type configuration in the following range

- lead of blade - 0.4 ÷ 0.6 b;

10 - mounting angle of cascaded block - 0 ÷ 5°;

- cascaded blade deflection - 0 4 ÷ 0 6 b,

- value of the shading factor - 0 3 ^- 0 5, in which b - value of the chord of blade profile * 5 The invention may be better understood from the following detailed description of an embodiment thereof due reference being made to the accompanying drawings, in which: Figure 1 shows schematic view cascaded configuration of blades; Figure 2 is a top view of wind motor rotor; and Figure 3 is a blade profile. 0 Wind motor comprises rotor 1 with power elements which are realized in the form of two symmetrically arranged blocks 2 and 3 of aerodynamic cascades whereinto each block advantageously consists of four blades 4 realized in the form of a turbine-type configuration of blades Blocks 2 and 3 of aerodynamic cascade are mounted on central vertical shaft 5 Blade profiles are in the form of subsonic aerodynamic profiles (Figure -^> 3) Efficiency of the suggested design of rotary cascaded wind motor is determined by selection of the lead ( γ ) of blade, mounting angle ( φ_p) of cascaded block, cascaded blade deflection ( χ ), value of the shading factor (K₃) and value of the chord of blade profile (b) It is established that values of the said parameters may be in the range of:

- lead ( γ ) of blade - 0.4 ÷ 0.6 b;

- mounting angle ( φ_p) of cascaded block - 0 ÷ 5°;

- cascaded blade deflection ( χ ) - 0.4 ÷ 0.6 b;

- value of the shading factor ( K₃) - 0.3 ÷ 0.5; in which: b - value of the chord of blade profile. However it is established in the process of testing of models equipped with subsonic aerodynamic blade profiles that the optimum values of the said parameters are as follow:

- γ = 0.5 b;

- Φ_P = 0°;

- X = 0.5 b;

- K₃ < 0.5;

Value of the chord (b) of blade profile is determined in dependance of number (Z) of blade profiles, selected values of shading factor ( K₃ ) and diameter (D) of the rotor of wind motor. It is established that that the optimum numer of cascaded blocks equals to two, but optimum range of number (Z) of blade profiles in each block does not exceed four. However the number of cascaded aerodynamic blocks of wind motor may be determined on conditions that the value of the shading factor K₃ < 0.5. According to the requirements of strength and power efficiency the most expedient number of blocks equals to two or three.

Rotary cascaded wind motor may be used in the most efficient way as a large power windmill having dimensions: diameter D > (6 ÷ 10) m; height H = (1.0 ÷ 1.5) D.

Single-unit power ( N ) of one row of aerodynamic blade profiles at optimum mode of operation may be determined by experimental dependence:

N = N/S = a x p x U_π710³ (kw/m²), in which:

N - total power of one row of two blocks, S - total area of blades arranged in one row of two blocks; U„ - peripheral velocity of blades arranged in one row of two blocks (m/sec); p - air density (kg/m^J); a - efficiency factor of aerodynamic characteristics of cascaded blade profiles; this factor is determined during testing of full-scale wind motors being equipped with specific blade profiles. Rotor of wind motor is rotating under action of wind actuating electrical generator or other equipment (not shown), ensuring conversion of wind energy into electrical or mechanical energy. The wind motor equipped with cascaded block in turbine-type configuration of aerodynamic blade profiles according to the results of testing of models allows: significantly to increase efficiency of wind motor due to more effective making use of aerodynamic characteristics of blade profiles in turbine-type configuration; practically the efficiency is more than 0.8 (ξ _max ≥ 0.8 ); - to increase power of wind motor due to keeping up specific speed of rotor because of widening of the variable range of value of the shading factor ( K₃) up to K₃ < 0.5 instead of K₃ < 0.3 since it was in connection with rotary wind motors of prior art; - to improve starting acceleration of the wind motor due to making use of turbine- type configuration of cascades. Further improvement of power parameters of wind motor may be achieved by improving aerodynamic properties of subsonic blade profiles used in turbine-type cascades of wind motors by means of using of mechanization devices for blades, e.g., by means of using of leading-edge flap, trailing-edge flap, discharging facilities of boundary layer etc.

The rotary wind motor in accordance with the present invention is industrially applicable due to the fact that the said wind motor may be manufactured and widely used in production of windmills for converting wind energy into electrical or mechanical energy.