Some contributions to aerodynamic theory for vertical-axis wind turbines
A review and modest extensions are described of quasisteady aerodynamic theory for performance prediction on Darrieus-type turbines. Results are given for both parallel-axis and curved-blade configurations. Blade stall and variable inflow are neglected; it is hypothesized that unsteady effects support the former approximation down to lower values of tip-speed ratio than hitherto believed. Both profile and induced drag are included, and their influences on power and downwind force are expressed in terms of elliptic integrals. Comparisons are presented with power data from the Sandia 2-m turbine. Three values of profile drag coefficient are employed, and it is argued that numbers in the range C/sub D/sub 0// approx. = 0.015 to 0.017 are most appropriate to the example chosen. Finally, a linearized analysis of unsteady flow effects on performance is summarized. Calculations suggest that they may be larger than might be expected in view of the low operating reduced frequencies of these machines.
- Research Organization:
- Stanford Univ., CA
- OSTI ID:
- 6521555
- Journal Information:
- J. Energy; (United States), Vol. 2:2
- Country of Publication:
- United States
- Language:
- English
Similar Records
Horizontal Axis Wind Turbine Aerodynamics: Three-Dimensional, Unsteady, and Separated Flow Influences
Improved double-multiple streamtube model for the Darrieus-type vertical-axis wind turbine