1. 研究目的与意义（文献综述）

in the 1980s, srahmed proposed the famous ahmed normalized model. and the ahmed model was analyzed experimentally in the low speed wind tunnel. by changing the posterior inclination of the model, the model surface pressure and the six component force were studied and tail flow field were measured. the research on the thermal comfort of the car occupants is mainly aimed at the study of the velocity field and the temperature field inside the compartment under the condition of opening the air conditioner. in 1974, nielsen in denmark took the airflow in the ventilated room as the object of study, and simulated it with cfd technology, which had a milestone significance for cfd in the field of hvac. gm's combination of cfd fundamentals, developed vine3d software, the software is the first dedicated to the car thermal environment analysis of common software. in 2007, meng qingchao of hunan university studied the velocity field and airflow organization in the cab and considered the pollutants in the cab, and made the concept of pollutant evaluation system in china. in 2008, tongji university, xiong kejia, zhang wanping combined with the impact of solar radiation, taking into account the passenger compartment comfort problems. in 2006, hunan university carried out a road test on a domestic car. when the speed reached a certain requirement, they shut down the engine to shield the engine noise from the impact of aerodynamic noise, and with no pattern of old tires to shield the tire on the impact of aerodynamic noise; they got the noise spectrum at two points in the car, but because there was no effective way to shield the driveline noise, the engineering reference value was limited. in 2008, yang bo, in the numerical simulation, proposed a new sub-domain numerical simulation method, that is, first simulate the renault time-averaged equation to determine the key regions that produce aerodynamic noise, and then extract the region for grid refinement. the steady-state results are mapped to the subdomains, and the large-eddy simulation is applied. the frequency domain characteristics of the noise are obtained. the results are compared with the experimental results. the results show that the two are in good agreement.

since the 21st century, with the increasing emphasis on energy conservation and emission reduction, coupled with the accelerated process of urbanization, macroeconomic regulations and policies to stimulate，the use of cars are more and more. the aerodynamic characteristics of the car has great influent on its economy and comfort. therefor, improving the aerodynamic performance of the car is an important means to improve its quality.

2. 研究的基本内容与方案

1. Introduce the basic theory and method of computational fluid dynamics (CFD), and summarize the turbulence model commonly used to calculate the external flow field.
2. Build a CAD model with an internal structure (seat, crew, dashboard, etc.)
3. Carry out numerical simulation for different windows in cars by using CFD software, including pre-treatment, mesh, set the boundary conditions, solving, post-processing.
4. Analyze the characteristics of the internal and external flow field of the city bus under different working conditions. On the basis of this, analysis of the human body near the head of the air flow. So as to make the evaluation of thermal comfort under different working conditions.

5. Simulate the pressure fluctuation of the monitoring point when the inter-city highway car opens the skylight, and obtain the noise spectrum through the Fourier transform.

3. 研究计划与安排

1. (7 semester 19, 20 weeks) determine the graduation project topic, graduate design task book (parameters), school data collection

2. (8 semesters week 1) program ideas, literature search, complete the opening report

3. (8 semesters 2-3 weeks) outside the school internship, school data collection, complete the internship report

4. 参考文献（12篇以上）

[1]tong ling,chen jiangping.empirical formula of indoor temperature field distribution characteristics of car air - conditioned car [j].automotive engineering.1999,21(4)243~247s

[2]xiao zheyi．research on aerodynamic noise of high speed vehicle[d]．changsha: hunan university，2007

[3]sun xuejun.study on numerical simulation of air flow field in air-conditioned car room and optimization of automobile air-conditioning system [d]. shanghai: shanghai jiaotong university.1996.