温室自然通风量计算中风压系数的研究

Wind pressure coefficient in natural ventilation rate calculation of a greenhouse

针对温室通风量计算中风压系数选用与风载体型系数相同取值而导致通风量计算结果不准确的问题,采用模拟方法研究风压系数的取值。从物理意义角度阐述了风压系数与风载体型系数的不同;通过理论分析得到了与计算风载体型系数不同的风压系数计算方法;对双坡屋面单栋温室采用Fluent数值模拟方法,得到了温室窗口开启及关闭2种情况下对应的风压系数和风载体型系数。模拟结果表明:温室通风窗口关闭时风载体型系数与窗口开启状态下风压系数取值有较大差异;与风载体型系数相比,风压系数的绝对值迎风面较小,背风面较大,相同部位风压系数和风载体型系数绝对值最大偏差是风载体型系数的60%。在温室通风量计算中风压系数不宜选取与温室风荷载计算中的风载体型系数相同的值。

The wind pressure coefficient used for greenhouse natural ventilation rate is similar to the wind load figure coefficient for greenhouse wind load calculation. In this paper authors differentiated them efficiently through theoretical analysis by which we can find the method of obtaining the wind pressure coefficient. Applying FLUENT software, in con- dition of window closed and opening to greenhouse of single-span and two-sides, authors simulated the wind pressure coefficient and wind load figure coefficient. Contrasted of two parameters, their values have a big difference; when the wind pressure coefficient is compared to wind load figure coefficient, the value of windward is smaller, the absolute value of leeward is bigger and in the same part the biggest difference is 60%. So, if the value of wind pressure coefficient used in greenhouse ventilation calculation is the same as the value of wind load figure coefficient, the calculation will result in a big error.