Question

In DETAILS what is the effects of the number of blades on the Darrieus wind turbine performance.

please in details and clear

Answer 1

The theoretical turbine performance model developed indicates that the only influence of the number of blades is through its effect on solidity (a = NcL/A ). It is obvious that a blade in the downwind half of its revolution sdoes not see the same induced velocity field as when in the upwind half of its revolution and that the interference effects should probably be some function of the number of blades. In order to determine the magnitude of this effect, the solidity and Reynolds number were kept fixed while the number of blades was varied, Theresults of these tests are presented in Figures 13 and 14 for Reynolds numbers of5 5approximately 1.5x10 and 2.0x10 . It appears that the three-bladed configuration is slightly better than the two-bladed configuration. The difference seems to be the most pronounced in the tip-speed ratio range of 3 to 4 and increases with increasing Reynolds number. The peak power coefficient does not appear to be markedly affected by the number of blades for a given solidity, A satisfactory explanation for this behavior has not been found..

Constant Re Runs o = 0.2, Re = 155,000 (nominal) 0 Run N Conf 14 3 3 1924 2088200 0.000888 88 8 OOOO 00000000 0000040 x - R Figure 13. Effect of Number of Blades on Power Coefficient Data at o = 0.2 and Rec - 155,000 Constant Re, Runs = 0.2, Re - 200,000 (nominal) O Run N Conr 15 3 3 2024 pogoo OOOOOO OOO OOO OB 708 806 8000 2 . Figure 14. Effect of Number of Blades on Power Coefficient Data at c = 9.2 and Red - 200,000