Wind Energy

186 S. Dovgy et al.
blades the coefficient of windrotor torque Cm at blades control increases 2
times in comparison with windrotor models with rigidly fixed blades. At the
same time, the value of coefficient Cm of the windrotor model with 2 blades
increases for the model No. 1 only by 30%, and for the model No. 2 by 15–20%.
The measured values of the overall hydrodynamic drag for both models
showed that for both windrotor models with blades control a significant
decrease in coefficients of hydrodynamic drag was observed, both average
Cxav, and maximal Cxmax. Thus, for the windrotor model No. 2 coefficients
Cxav and Cxmax decreased by 30–40%, while for the windrotor model No. 1
those decreased by 3–4 times.
Let us add, that coefficients Cp and Cm were calculated at flow density
is equal to 1,000 kg m −3 , that is approximately 750 times the density of air,
therefore it will be wrong to compare the results obtained in this work with
other known experiments in literature, done in the air environment. From the
point of view of advantages of one design of windrotor relative another, we
can compare here only our results obtained in absolutely identical conditions
of experiment.
33.4 Results
Very high value of the coefficient of rotor torque and low value of self-start
speed of windrotor with the investigated mechanism of blades control allow
hoping, that wind-plants with such rotors can be rather effective even at rather
low speeds of a wind flow as pumping facilities for extraction of water or oil
from wells.