Experimental Comparison Of Three Numerical Methods For Wind-Driven Natural Ventilation In Building Rooms

The use of natural ventilation in the transitional season can reduce the use time of air conditioners,increase the frequency of ventilation and indoor air quality throughout the year.The natural ventilation of wind pressure is influenced by many factors,and the complexity of the internal layout of multi zone buildings is very difficult to accurately predict the natural ventilation volume of buildings.Seeking a more accurate and fast calculation model of natural ventilation is of great significance for the more effective use of natural ventilation.Multi-zone network model,CFD model and coupling model are three commonly used numerical models in the field of natural ventilation.Various numerical models have their own merits and demerits and application scope.In this paper,the principles of these three numerical models are expounded.In this paper,three numerical model methods are verified by single and double room model wind tunnel experiments.The study shows that if the open flow coefficient is set to a constant 0.61,the results of the multi area network model method will produce large error.The coupling model method takes the front room of a double room as the CFD area,which can "identify" the influence of the location of the partition door on the indoor ventilation resistance,so as to get more accurate results than the multi area network model method.Large eddy simulation(LES)for single and double zone models is carried out to verify the accuracy of the CFD numerical method.A four compartment model wind tunnel experiment is used to compare three numerical models,and the experimental single wind speed condition is extended.The study shows that the ventilation rate in the inflow building calculated by the CFD method is the closest to the measured value;the coupling model method is the next,and the multi area network model method has the greatest error.The accuracy of the CFD model is verified by comparing the indoor flow field calculated by the CFD method with the measured flow field.For the indoor ventilation rate,the results of the multi area network model are inaccurate,and the coupling model can get accurate results only when the flow direction is perpendicular to the windward surface,and the calculation results are more and more distorted when the wind direction deviates from the working condition.This subject is to simulate three types of residential units and six kinds of natural ventilation under wind speed conditions.The multi area network model and the coupling model method are used to evaluate the results based on the CFD method.The study shows that the results of the network model and the coupling model are often more accurate for the outdoor wind directly through the windward window,and the air flow needs to enter the area from the inner door.The results of the two models will have large error.The causes of errors in the two models are analyzed respectively.Finally,with the help of jet theory,the momentum effect of airflow retained indoors is explained.