The rotating blades of a horizontal axis wind turbine generator (WTG) can distort the video portion of a TV signal and thereby interfere with TV reception in the vicinity of the WTG. The nature of this interference is discussed and methods are described for calculating the approximate zone within which the interference is judged severe. All necessary information is provided for predicting the interference zones about MOD-0 and MOD-0A, and MOD-1 machines for any given TV transmitter using graphical procedures. The effects of any terrain inhomogeneity, irregularity, or adjacent structures are ignored.
Separate abstracts are included for each of the 26 papers presented concerning the design and performance of wind turbines.
This aerodynamic research program was aimed at providing a reliable, comprehensive data base on a series of wind turbine models covering a broad range of the prime aerodynamic and geometric variables. Such data obtained under controlled laboratory conditions on turbines designed by the same method, of the same size, and tested in the same wind tunnel had not been available in the literature. Moreover, this research program was further aimed at providing a basis for evaluating the adequacy of existing wind turbine aerodynamic design and performance methodology, for assessing the potential of recent advanced theories and for providing a basis for further method development and refinement.
Survey of historical and current site selection techniques for the placement of small wind energy conversion systems |
Individuals and groups who purchase and install wind energy conversion systems (WECS) for either generation of electricity or pumping water have to go through a process by which a specific location is selected for each WECS. The purpose of this study was to identify and document methods and practices used in siting of WECS. The study covers the period from the early 1900s to the present day. 174 references.
Several aspects of power estimation techniques for wind energy conversion systems are studied. The sampling rate at which data are collected, ranging from once every 2 minutes to once every 3 hours, does not appear to significantly affect the average power for recording periods of one season. Increased averaging times produce small underestimates (less than 10 percent) of available power. The Rayleigh and Weibull distributions both give poor estimates of power for low mean wind speed situations, with the former being significantly worse. At higher wind speeds, both give good estimates, and the Rayleigh distribution is considerably simpler in form and application. A height extrapolation scheme for Weibull parameters is also investigated. Results are satisfactory for power estimates of ensembles of machines, but the scatter of values about the mean makes the method inappropriate for individual cases.
A technique is presented for estimating the average power output of a wind turbine using, as the wind characteristic input, only the mean annual wind magnitude. Hourly wind speeds are assumed to have a Rayleigh frequency distribution which requires a single parameter input (e.g., the mean value, variance or higher moment values). Based upon a general shape, for the wind speed versus machine output, a generic set of curves is developed to estimate the average power output of wind turbines. Also, estimates of the percent of time the wind turbine would not produce power (percent down time) and the percent of time the wind turbine would be operating at its rated power are presented.
Giromill wind tunnel test and analysis. Volume I. Executive summary. Final report, June 1976--October 1977 |
The study described herein is a continuation of the Giromill investigation in which a wind tunnel test of a model Giromill rotor was performed. The primary objective of the wind tunnel test was to obtain data for comparison with the Larsen cyclogiro vortex theory program employed for predicting the Giromill performance. The model had a rotor diameter of 7 ft. (2.13 meters) and a solidity (total blade area divided by rotor span times diameter) of 0.3. This was achieved by a three bladed rotor having blade chords of 8.4 in. (21.3 cm) and a span of 5 ft. (1.52 meters). The blades were modulated by use of replaceable cams, that simulated the various operating conditions, and a push rod arrangement connected to a bellcrank about the blade pivot point. Rotor RPM control was achieved with an electric motor/generator that could be used to either drive the rotor or absorb the rotor power to maintain RPM.
Giromill wind tunnel test and analysis. Volume II. Technical discussion. Final report, June 1976--October 1977 |
A wind tunnel test of a Giromill rotor was conducted. The objective of this test was to substantiate the performance computed by the Larsen cyclogiro vortex theory. Additional objectives were to obtain performance comparison data between the Giromill, a sinusoidal blade modulation Giromill, a Darrieus rotor, and a modified Darrieus rotor that flips the blades a few degrees. A three bladed Giromill rotor having a diameter of 2.13 m (7 ft) and a span of 1.52 m (5 ft) was tested in the McDonnell Aircraft Company 15 x 20 ft Mini Speed Wind Tunnel. The blade modulations were accomplished through use of a cam and push rod arrangement. Replaceable cams provided the desired blade modulation at the various operating points. Various operating conditions were achieved by adjusting the rotor RPM and tunnel speed. The results show that the Giromill has good performance, equal to or much better than that predicted by theory, and outperforms the other types of vertical axis wind turbines tested.
SUMMARY OF THE DEVELOPMENT PLAN FOR THE WIND CHARACTERISTICS PROGRAM ELEMENT OF THE FEDERAL WIND ENERGY PROGRAM |
The development and commercialization of durable and economically viable Wind Energy Conversion Systems (WECS) is the primary goal of the Federal Wind Energy Program (FWEP). Within this program, the Wind Characteristics Program Element (WCPE) has been established to identify, develop and disseminate information on related wind characteristics. The WCPE is a service for designers, manufacturers, users of WECS, other program elements within the FWEP, and Department of Energy (DOE) staff. Research funded by the WCPE must be directly related to the needs of one of these groups. The primary role of Pacific Northwest Laboratory (PNL) in the WCPE is the administration of wind characteristics research under the guidance of DOE Headquarters. Research within the WCPE has been grouped into four technical program areas: • Wind Characteristics for Design and Performance Evaluation • Mesoscale Wind Characteristics • Development of Siting Methodologies • Wind Characteristics for Operations. In addition, a special studies section has been established for providing direct assistance to the Wind Systems Branch, DOE, in new problem areas needing immediate attention. The Wind Characteristics Design and Performance Evaluation program area is to provide critical design wind characteristics to DOE/HQ, as well as to assemble general wind and environmental characteristics for WECS design and performance evaluation. The information will be compiled into two handbooks to be used by public and private WECS designers and evaluators: Environmental Desig!!..Criteria for WECS, and Hind Characteristics for WECS Performance Evaluation. The fi~st environmental design criteria handbook is scheduled to be completed at the end of FY-1978. Supporting tasks are funded in FY-1978 to provide input to the handbooks. The Mesoscale Wind Characteristics program area has two main goals. The first is to develop and present analyses of the wind energy potential over large areas. These analyses are to identify smaller areas of favorable wind characteristics and to quantify the wind energy potential over the whole area. The results of these large area analyses will guide preliminary decisions on WECS implementation. The results will also allow estimation of the reliability of wind energy for single units and for multiple WECS in dispersed arrays. The second major goal of this program area is to analyze the wind energy potential at specified locations, e.g., at sites which are candidates for testing and demonstrating wind machines. Supporting studies will provide additional analytical and data management techniques to improve the large area analyses. These techniques will also improve the evaluation of wind characteristics at candidate sites, where limited data are available. The Siting Methodologies program area will develop effective and economical methods for selecting good WECS sites. These methods form the basis of siting strategies that will be presented in handbooks. Two interim siting handbooks have been prepared and are being reviewed. They will be published during FY-1978 and updated in the coming year. The current emphasis of the numerical modeling efforts in this program area is on their verification and demonstration. The Wind Characteristics for WECS Operation program area is to provide wind predictability/uncertainty characteristics needed by those concerned with WECS operations in a power grid. The short-term product of this program area is to report on wind prediction uncertainty. The long-range product of this area is to upgrade specialized forecasting techniques tailored to the needs of WECS operations.
Technical and management support for the development of wind systems for farm, remote, and rural use. Annual report, October 1976--September 1977 |
During FY1977, the Test Center has been established and a total of eight WTG's have been mounted on towers for testing. At year end, five were undergoing tests, two had been returned to the manufacturers for retrofit of design improvement, and one had been destroyed in a wind storm. In addition, two WTG's were being assembled and prepared for testing and one machine was on order. Specific design improvements have been identified and implemented on two WTG's as a direct result of rf testing. The high-speed data acquisition system at the test center is not yet operational, though the hardware and software are both nearing completion. The system, when completed, will be capable of continuous monitoring of the performance of all the machines at the site as well as intensive testing for measurement of engineering data on any given WTG. Efforts under Task V (Standards Development) have resulted in an informal survey of the wind energy community's opinions on the direction Standards Development should take. Information dissemination has resulted in distribution of approximately 25,000 brochures, with a potential exposure of nearly 200,000 persons, construction of a traveling display, and continuous interface with local and national news media.