Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Uludağ Üniversitesi, Turkey
Approval Date: 2010
Thesis Language: Turkish
Student: GÖKHAN SEVİLGEN
Supervisor: MUHSİN KILIÇ
Abstract:In this study, three dimensional numerical analysis of temperature and air flow distribution in the automobile cabin were performed by using Computational Fluid Dynamics (CFD) method. For this purpose, a three dimensional automobile cabin including window and outer surfaces was modeled by using the real dimensions of a car. To evaluate the results of numerical analysis according to thermal comfort, a virtual manikin divided into 17 parts with real dimensions and physiological shape was added to the model of the automobile cabin. Air flow, local and average thermal characteristics of the human body surfaces and temperature distributions of the cabin surfaces were obtained from the results of the 3D steady and transient numerical analyses for standard heating and cooling period of the automobile cabin. In the numerical simulations, different types of boundary conditions on the human body surfaces were used to determine the suitable boundary condition for evaluating thermal comfort. In the numerical analyses, different types of mesh structures were used to achieve optimum mesh structure in terms of computing time and precision results. S2S (Surface-to-Surface) model, including view factors, and DO (Discrete Ordinate) model were used for the calculation of radiation heat transfer among the interior surfaces of the cabin and the results were compared each other. In the standard cooling period, simulations were performed with different types of inlet vent(s) considering that the cooling load of the automobile HVAC system was same in all simulations. Therefore, the effects of selecting different type of inlet vent(s) on the air flow, temperature, and relative humidity distributions of the automobile cabin were investigated during the cooling period. Transient cooling simulation of the automobile cabin considering the solar radiation effects was also performed to determine the air flow distribution, local and average thermal characteristics of the human body and temperature distributions of the cabin surfaces. In the majority of the numerical simulations of this thesis, validations of the numerical results were achieved by comparing to the results of the experimental studies performed simultaneously with the numerical analyses.Highly transient conditions were obtained in the first 15 and 20 minutes of heating and cooling periods in the automobile cabin. Considering the physiological models of the human body, it can be said that using the constant temperature boundary condition on the human body surfaces is more realistic compared to the constant heat flux boundary condition for evaluating the thermal characteristics of the human body surfaces. In the majority of the numerical simulations of this thesis, the temperature differences between calculated and measured values in the automobile cabin environment were obtained about 2 °C in generally. S2S or DO model can be used for the calculations of the radiation heat transfer among the cabin interior surfaces but these models show differences in terms of computation and preprocessing time. Considering the heat interactions between human body surfaces and cabin environment, convective heat transfer has a great effect on the human body at the beginning of the heating period but radiative heat transfer has an important role on human body when the steady state conditions are approached. From the results of the cooling simulations with different type of inlet vent(s), air flow, temperature and relative humidity distributions have different structure in all cases. From the results of cooling simulations including solar radiation, high temperature values were calculated at the surfaces directly affected by the solar radiation in the automobile cabin and mean temperature of these surfaces was decreased slowly compared to the other surfaces during the cooling period.