- Wind engineering
Wind engineering is a field of
structural engineeringdevoted to the analysis of windeffects on the natural or built environmentto protect it from possible damage. It includes strong winds which may cause discomfort as well as extreme winds such as tornadoes, hurricanesand storms which may cause widespread destruction [ [http://www.ecs.csun.edu/~shustov/Wind_Engineering_Directory.html Wind Engineering Directory] ] .
Wind engineering draws upon
meteorology, aerodynamics, Geographic Information System, Wind energy, Air Pollutionand a number of specialist engineeringdisciplines. The tools used include climate models, atmospheric boundary layer wind tunnels and numerical models. It involves, among other topics, how wind impacting buildings must be accounted for in engineering.
Wind engineering may be considered closely related to
earthquake engineeringand explosion protection.
Wind Engineering as a separate discipline can be traced to the UK in the 1960s, when informal meetings were held at the
National Physical Laboratory, the Building Research Establishment and elsewhere.
Wind loads on buildings
The design of buildings must account for wind loads, and these are affected by wind shear. For engineering purposes, a power law wind speed profile may be defined as follows:cite book | last = Crawley | first = Stanley | title = Steel Buildings | publisher = Wiley | location = New York | year = 1993 | isbn = 0471842982 | pages = p. 272 ] cite book | last = Gupta | first = Ajaya | title = Guidelines for Design of Low-Rise Buildings Subjected to Lateral Forces | publisher = CRC Press | location = Boca Raton | year = 1993 | isbn = 0849389690 | pages = p. 49]
: = speed of the wind at height : = gradient wind at gradient height : = exponential coefficient
Typically, buildings are designed to resist a strong wind with a very long return period, such as 50 years or more. The design wind speed is determined from historical records using
Extreme_value_theoryto predict future extreme wind speeds.
Wind turbines are affected by wind shear. Vertical wind-speed profiles result in different wind speeds at the blades nearest to the ground level compared to those at the top of blade travel, and this in turn affects the turbine operation.cite book | last = Heier | first = Siegfried | title = Grid Integration of Wind Energy Conversion Systems | publisher = John Wiley & Sons | location = Chichester | year = 2005 | isbn = 0470868996 | pages = p. 45] The wind gradient can create a large bending moment in the shaft of a two bladed turbine when the blades are vertical. [cite book | last = Harrison | first = Robert | title = Large Wind Turbines | publisher = John Wiley & Sons | location = Chichester | year = 2001 | isbn = 0471494569 | pages = p. 30] The reduced wind gradient over water means shorter and less expensive wind turbine towers can be used in shallow seas.cite book | last = Lubosny | first = Zbigniew | title = Wind Turbine Operation in Electric Power Systems: Advanced Modeling | publisher = Springer | location = Berlin | year = 2003 | isbn = 354040340X | pages = p. 17]
For wind turbine engineering, an exponential variation in wind speed with height can be defined relative to wind measured at a reference height of 10 meters as:
: = velocity of the wind at height,
[m/s]: = velocity of the wind at height, = 10 meters [m/s]: = Hellman exponent
The knowledge of wind engineering is used to analyze and design all
high risebuildings, cable suspension bridges and cable-stayed bridges, electricity transmission towers and telecommunication towers and all other types of towers and chimneys. The wind load is the dominant load in the analysis of many tall buildings. So wind engineering is essential for the analysis and design of tall buildings. Again, wind load is the dominant load in the analysis and design of all cable bridges, especially the cable bridges which contain rail lines.
* [http://www.iawe.org/ International Association of Wind Engineering]
* [http://www.aawe.org/ American Association of Wind Engineering]
* [http://www.ukwes.bham.ac.uk/ UK Wind Engineering Society]
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