Research On Resistance Characteristic Of Natural Ventilation Through Large Opening

In recent years, more and more attentions is paid to energy consume and environment in buildings. With arising of sustainable development, the old technology of natural ventilation is regarded again. Reasonably utilization of natural ventilation can supply fresh air and improve indoor environment for human being's health and meet require of approaching the nature. Presently, natural ventilation technology is not perfect, mature and reliable software is lacked to exactly forecast flow of natural ventilation. It's necessary to discuss the theory of natural ventilation and factors.Firstly, the present issues of natural ventilation are summarized in this paper. The basic issues of natural ventilation and the resistance characteristic of large opening in residential buildings with wind pressure ventilation are analyzed. And the discharge coefficient of large opening is discussed comparing with pipe flow theory. It shows that total pressure drives the air flow through large opening. And the calculation of discharge coefficients must follow the terms of Bernoulli equation.Secondly, the form of large openings is analyzed and an investigation is processed on windows of residential building with questionnaire. It shows that the usage rate of push-and-pull window is very high and the prevalent problem is that the opening area of windows is too small.Finally, CFD numerical simulation technology is used in this paper. The calculated surface of air flow is confirmed. Several ventilation model cases are simulated to analyze the influence factors of resistance characteristic, such as outdoor flow velocity, building porosity, outdoor flow angle and different opening area in opposite walls, in each case the flow field and discharge coefficient is discussed. In addition, multiplex region model case is also discussed in this paper. In a word, natural ventilation resistance characteristic of residential building openings is discussed in this paper, several building models are simulated with CFD numerical simulation technology, kinds of discharge coefficients is achieved, it provides ample data for project applications and establishes base for further research on natural ventilation.