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Temperature gradient and wind profile effects on heavy gas dispersion in build up area
, Article Journal of Applied Sciences Research ; Volume 6, Issue 12 , 2010 , Pages 6010-6020 ; 1816157X (ISSN) ; Shahraki, F ; Rashtchian, D ; Behzadmehr, A ; Sharif University of Technology
Abstract
Dispersion of heavy gases is considered to be more hazardous than the passive ones. This is because it takes place more slowly. In this paper, based on the extensive experimental work of Hanna and Chang, the CFD model (Ansys-CFX) was tested compared with Kit Fox experiments. In order to accomplish this validation, the multiphase approach was employed as a new method in this area. In addition, the temperature gradient effects were investigated. The survey of wind speed was done taking factors such as time, height and direction into the consideration. To reduce the number of elements in computational domain, a combination of 2D and 3D geometries were utilized. Results showed that the wind...
Temperature gradient and wind profile effects on heavy gas dispersion in build up area
, Article Australian Journal of Basic and Applied Sciences ; Volume 4, Issue 12 , 2010 , Pages 6010-6020 ; 19918178 (ISSN) ; Shahraki, F ; Rashtchian, D ; Behzadmehr, A ; Sharif University of Technology
Abstract
Dispersion of heavy gases is considered to be more hazardous than the passive ones. This is because it takes place more slowly. In this paper, based on the extensive experimental work of Hanna and Chang, the CFD model (Ansys-CFX) was tested compared with Kit Fox experiments. In order to accomplish this validation, the multiphase approach was employed as a new method in this area. In addition, the temperature gradient effects were investigated. The survey of wind speed was done taking factors such as time, height and direction into the consideration. To reduce the number of elements in computational domain, a combination of 2D and 3D geometries were utilized. Results showed that the wind...
Smooth switching in power control of wind turbines using a combination strategy of hysteresis and modified middle regions
, Article Sustainable Energy Technologies and Assessments ; Volume 37 , 2020 ; Moradi, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper presents a new method for protecting the variable speed wind turbines in switching between different regions. With the objective of power maximization, the controller is applied in all regions. Since usually different methods and algorithms are used in different regions for controlling the wind turbines, smooth transition between these controllers is necessary for the safety and protection of turbine parts and structure. A two degree of freedom mechanical model is used and the simulations are performed and verified by FAST. The turbine is controlled by a rotor angular speed controller in the second region and an inverse dynamic pitch controller in the third region. The transient...