Intelligent wind power unit with tandem wind rotors - Wind Power Generation and Wind Turbine Design - page 335

Generator

Revolution
sensor

Revolution
sensor

Wind

Anemometer

Slide resistor

Revolution
counter

Ammeter
Figure 1 : Model unit with tandem wind rotors [ 3 ].

Voltmeter

40

V = 10 m/s

30

V = 8 m/ s

20

10

V = 6 m/s

0

0 200 400 600 800 1000 1200

Rotational speed min -1

Figure 2 : Output of tandem wind rotors [ 3 ].

of the rated output 3 kW (see Fig. 3, [5]). The each wind rotor rotates and the
armature as usual, while the mechanical effi ciency is 0.8. The numerical simula-
tion showed that the prototype with the tandem wind rotors can get nearly 85% of
the effective wind power, which is about two times higher than that of a practical
single rotor system. The fi eld tests suggested that the rear wind rotor can generate
the additional output from 25 to 40% on the same stream tube and the effi ciency is
high at the comparatively lower rotational speed.
Continuously, Jung et al. has proposed the tandem wind rotors consisted of the
front wind rotor with the diameter of 5.5 m, called the auxiliary rotor by them, and
the rear wind rotor with the diameter of 11 m, called the main rotor by them [6].