Numerical Simulation And PIV Test Research On Natural Ventilation Of Coupling Thermal Pressure And Wind Pressure

The natural ventilation is an ancient technology and has the application very early. After the air conditioning technology started the application, due to air conditioning technology has the good controllability, is not limited in use and so on, it has substituted for the natural ventilation technology gradually. However, the emergence of the energy crisis and the requirements about comfort and health, make people began to re-examine the natural ventilation technology. The reasonable use of natural ventilation may save the energy, provide the fresh air, improve the indoor air quality and meet the requirements of comfort and the health.According to the different driving force on natural ventilation, it can be divided into thermal pressure, wind pressure and coupling thermal pressure and wind pressure. There are heat source in all kinds of buildings and natural wind outdoor, therefore the natural ventilation of coupling thermal pressure and wind pressure is the most common form. Many factors affect the natural ventilation, make the mechanisms and rules of natural ventilation be complicated and diversified, therefore many questions wait for the deep research, especially the natural ventilation of coupling thermal pressure and wind pressure has become one of the difficult problems in the natural ventilation domain. Usually, rooms have single-sided aperture in which people live and work. Therefore, it is necessary to study the factors which affect the natural ventilation in this kind of room, which can guide the design of natural ventilation.This paper points out the background and the practical significance about the application of natural ventilation technology, introduced the domestic and international researches on natural ventilation and practical application, and expound the causes of natural ventilation and some basic theory. In main part of this paper, using PIV testing technique to test single-sided natural ventilation of coupling thermal pressure and wind pressure, mainly study three factors on the impact of airflow which are the strength of heat source, outdoor wind speed and aperture position, and using computational fluid dynamics simulation software Airpak to do numerical simulation on natural ventilation of coupling thermal pressure and wind pressure. Experimental and simulation results show that the enhancement of heat source can increase the ventilation quantity of natural ventilation; outdoor wind speed changes had no effect on natural ventilation; increasing the vertical distance between the two apertures which are on the same plane of the room makes the maximum air flow rate become bigger and the ventilation quantity of natural ventilation increase greatly. Through comparing the Numerical simulation results and experimental results, we know that it has certain confidence level in predicting the airflow of natural ventilation, can predict the approximate airflow outline, but still there are some differences in details. In practical applications, standard two-equation model which is verified by PIV testing technique can be used to guide the design of natural ventilation.