Three-Dimensional Numerical Analysis Of Ventilation Efficiency Of The Indoor Air Flow

The research of the ventilation efficiency is great important to the design of ventilating and air-conditioning engineering. many researches show that the Indoor Air Quality have close relation to the ventilation efficiency. based these researches acquired and using a mathmatical model, this thesis tries to research the contaminant concentration distributions of three -dimention indoor turbulent flow by means of computational fluid dynamics and heat transfer,and then works out the ventilation efficiency. A better desired ventilation form is acquired by comparing the three efficiency values .On the basis of recently materials collected in the field at home and abroad ,this paper adopts two-equation turbulence model by analysis and comparison,and sets up mathematical model to study three-dimentional indoor turbulent flow.Control-volume method and power-law scheme is used to discrete these differential equations. According to semi-implicit method for pressure-linked equations (SIMPLE algorithm),author writes a general program in C language for simulation of the velocity profile,temperature and pollution concentration distributions of indoor airflow ,and the writing, the debugging and the running of the program.all are completed in Microsoft Visual C++ 6.0 environment. Then author discusses the writing and debugging of the program.The ventilation of a typical chamber with a stable fixed pollutant emission is studied by founding different boundary conditions (here,they are the both up inlet and outlet on opposite side,the up-inlet and down-outlet on opposite side and the up-inlet and down-outlet on the same side .). and accordingly dividing different grids.Using the program, the velocity values and the pollution concentration values of the chamber are worked out . Then by using the Excel software,we get the figures of the velocity profile and pollution concentration distribution of different sections, and get the ventilation efficencies of the three ventilation forms.As view from the efficiency of the draining pollution, a desired ventilation is regarded as the up-inlet and down-outlet on the same side after compairing the three ventilation efficiency .The trend of the velocity profile and the pollution concentration distribution both are basically identical with the practice,and the numerical results of the ventilation efficency accord with the ones studied by prof. Ma Renming. It is concluded that the mathematical model andnumerical method adopted in this article is reasonable and reliable.