A Characterization of Vertical Axis Wind Turbines
Vertical axis wind turbines (VAWT) have a number of advantages over the horizontal axis wind turbines (HAWT), however the performance is a little smaller, so that researches for their development should be continued for the implementation of these turbines in urban environment for electrical energy generation. This paper provides an overview of characterization of the VAWT, through a literature review, making comparisons with the HAWT and highlighting the advantages and disadvantages of this type of turbines. The paper also defines and compares the main exist types of VAWT for application in urban environment, so that aims to be a first step towards development of a VAWT research. Finally, this paper features how the aerodynamic optimization of a VAWT can be obtained, defining the experimental and the computational numerical analysis, by the relationship between them.
Performance Analysis and Structure Optimization of a Nautilus Isometric Spiral Wind Turbine
Background: This paper proposes a Nautilus isometric spiral vertical axis wind turbine, which is a new structure, and its aerodynamic performance and power generation performance need to be analyzed. Methods: A 3D model of the wind turbine was built and its aerodynamic performance was analyzed. Then the wind turbine power generation and grid-connected simulation platform was built by MATLAB/SIMULINK, and its power generation performance and subsequent grid connection were studied. Results: The basic parameters of the wind turbine were obtained. In order to improve efficiency, parameters such as pressure, torque, wind energy utilization rate and relative velocity of wind turbines with different blade numbers and different sizes were compared. In addition, by building a simulation platform for the power generation control system, the power generation characteristics and grid connection characteristic curves of the generator were obtained. Conclusions: When the number of blades is three and the ratio between the ellipse major axis and minor axis of the blade inlet is 0.76, the best efficiency of the wind turbine can be obtained. Application of the power generation control system used in this paper can achieve grid-connected operation of this wind turbine. It also confirmed that the Nautilus isometric spiral wind turbine has good performance and is worthy of in-depth research.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.