The Numerical Simulation Of Natural Ventilation Flow In Single-zone Model Buildings With Large Opening

With the development of the air conditioning technology, the natural ventilation has been neglected for a long time. However, the indoor air quality problem and residents health problem caused by enclosed air conditioning, and the strategy of sustainable developmen make scientists and other relevant personnel value the natural ventilation highly again.Reasonable use of natural ventilation not only can save energy but also can provide clean, comfortable and healthy natural wind to improve indoor air quality and safeguard healthy indoor living environment for human. But as the modern urban layout develops and building structure form evolves, the use of natural ventilation in contemporary buildings are more complex and more unstable than in traditional buildings,while people's requirements for indoor airflow are raising. So the research task of natural ventilation is harder. Therefore, this article which takes the natural ventilation state under many conditions of single-sided and bilateral large openings of as research subject will have theoretical and practical significance in improving people's living environment.. Firstly, this paper points out the academic background , the theoretical and practical significance of the research subject. Then it reviewes the theory progress and the development conditions of natural ventilation under big openings. Next it puts forward the research focus, difficulties and some important influencing parameters.This paper uses the Computer Fluid Dynamic software(Fluent), to make simulation analysis of natural ventilation state in the case of the single-sided big openings.On one hand, it proves the validity and feasibility of the Fluent in simulating the natural ventilation,and it also verifies some classic expression of natural ventilation flow on the other hand.The paper analyzes the natural ventilation effect and influencing factors under the joint action of one open air pressure, wind pressure in different open area , indoor and outdoor temperature, heat producer. And it points out t leading driving force under the joint action of thermocompression , wind pressure. And the author also believes that there are mutual gain and mutual inhibition between thermocompression and wind pressure under such conditions, which has certain theoretical significance in design of natural ventilation in unilateral big openings.Through the simulation of natural ventilation in bilateral openings, the author got the result that there is no substantial distinction between unilateral open and bilateral openings in pure thermocompression ,that is, bilateral openings can be took as the superposition of two unilateral openings. As for flow coefficient,the bilateral open flow coefficient should take different values after the autor compares the simulation value, calculation value and some the experimental value done by the prehominid .As for natural ventilation driven by the joint action of temperature difference and wind pressure, the autor simulating the air volume, comparing and analysing the simulation results gets that the air volume should be the bigger one when each of them work alone.Finally, this paper also simulates and analyses the sine type incoming flow speed of single-sided and bilateral natural ventilation in different cycle, different amplitude cases, it reveals that the sine type incoming flow achieves in the foundation of steady flow plus the sine type disturbance. So the sine type incoming flow doesn't change the indoor and outdoor current flowing features in essence and the calculation results of wind speed of sine type incoming flow and steady flow are alike.