Analysis Of Effective Ventilation Of Single-Sided,Wind-Driven Natural Ventilation In Buildings

Compared with air conditioners,natural ventilation has the characteristics of economy and comfort.Under the conditions of advocating sustainable buildings,natural ventilation has received the attention of scholars.Natural ventilation can be divided into single-side ventilation and bilateral ventilation,due to the privacy requirements of space and the obstruction of furniture,single-sided natural ventilation is common in real life.At present,many studies focus on the average ventilation at the opening,but there is little research on the effective ventilation of buildings.In this context,the field measurement and numerical simulation of a single-side,wind-driven natural ventilation are mainly carried out in this paper.Firstly,three kinds of methods for predicting the ventilation of single-side natural ventilation are introduced in detail:the interface velocity extraction method,the tracer gas concentration attenuation method and the constant rate attenuation method.For experimental subjects,numerical simulation using FLUENT software.The above three kinds of ventilation calculation methods were reproduced in CFD,and the simulation results obtained by different calculation methods were compared with corresponding experimental data and existing empirical models.and it was found that the concentration attenuation method and the constant rate attenuation method can calculate the effective ventilation,and the former could perform better prediction.By analyzing the ventilation volume under different monitoring volume,it was found that the concentration distribution of CO₂ in the chamber during the whole process of concentration attenuation was relatively uniform.Secondly,parameters that can better reflect the effective ventilation are analyzed—the mixing coefficient and the effective depth of the fresh air.The applicability of the existing formula of the mixing coefficient was discussed,and the mechanism of effective deepening of the fresh air under the action of wind pressure and hot pressure was analyzed.The trace gas concentration decay method is used as the calculation method for the indoor effective ventilation volume.The interface velocity extraction method is used as the calculation method for the average ventilation volume of the building openings.Single-sided natural ventilation buildings with different wind speed,opening position,opening size and building size were simulated,and analyze the influence of various factors on the average ventilation,effective ventilation,mixing coefficient and effective depth of fresh air.Finally,considering the actual life,the physical model is more complex,using the same simulation and calculation methods to simulate a single-sided multi-opening natural ventilation building,and discuss the relationship between the flow rates of different openings in the case of different numbers of openings on the windward side.The relationship between the effective ventilation of the building and the total average ventilation volume at the openings,and the flow field around the building were also analyzed.The conclusions of this paper can provide some reasonable suggestions for the design and assessment of natural ventilation in buildings,and help to increase the effect of natural ventilation on indoor gas exchanging.