The Research On Numerical Simulation And Frequency Control Of Ventilation System In An Underground Garage

Based on computational fluid dynamics theory and software FLUENT as the operational platform, numerical simulation analysis of the air distribution and contaminant density field of the ventilation of an underground garage is made in this thesis. In order to improve indoor air quality of underground garage and save energy of ventilation system, frequency control of VAV of underground garage is researched.There are four aspects of work done as following:Firstly, a brief review on the aspects of how to improve ventilation efficiency of underground garage and the conditions of numerical simulation researches on air distribution in underground garage by scholars is made at home and abroad.Secondly, the application CFD software FLUENT simulates air distribution in ventilation underground garage. The simulations on basis of theκ?εtwo-equation turbulent model widely used in engineering are made by the method of control cubage which has a plainness concept. Discrete equation systems are solved with the SIMPLE algorithm. The velocity and the CO density distributions in the underground garage are drew. The results of the simulations are analyzed. In order to analyse the differences between them, the measured data are compared with the data of the results of simulations. At last, the feasibility and reliability of the numerical simulation are demonstrated.Thirdly, two improvement programs are pointed out, against the main factors of affect the efficiency of ventilation underground garage. Based on the ventilation effect revealed by the post-processing graphics educed by CFD simulation, the velocity field and the CO density field distributions for two improved system prove that the improvement systems have wonderful effectiveness. By dynamic numerical simulation of the three ventilation programs in the underground garage, the dynamic changes of the velocity field and the CO density field distributions are found out. And then, the dynamic calculation methods of this program and relevant experiences will be made.Fourthly, by the feasibility analysis of the frequency control strategy of ventilation in an underground garage, the improvement program based on the concentration of CO transformation is pointed out. The frequency control principles and methods of fans are highlighted. By the example of project, the process of variable frequency control used in underground garage ventilation system is introduced. The energy saving potential of the project is also analyzed.