空调轿车车室内气流组织的数值模拟

【作者】 杨娟；

【导师】 杨启容；

【作者基本信息】 青岛大学 ， 车辆工程， 2006， 硕士

【摘要】 本文以空调轿车车室内的空气为研究对象,详细分析了车室内的空气流动与传热,以计算流体动力学(CFD)为基础,采用RNGκ-ε双方程模型和壁面函数法,对空调轿车进行了合理的简化,考虑到太阳辐射,人体热边界等,建立了空调轿车车室内的三维紊流模型,得到了空调车室内温度场、速度场的控制方程。 就不同的送风速度、送风温度、送风角度以及送风口位置等,对车室内气流组织进行了定性、定量的比较分析。以FLUENT作为数值模拟平台,得到了速度场以及温度场的数值解,并对四种典型情况下的速度场和温度场进行了分析。用TECPLOT软件将计算结果可视化,得到各特征断面温度场和流场的分布图。求得工作区域的速度不均匀系数、温度不均匀系数以及空气分布特性指标,为车室内气流组织分布的优化设计提供依据。 结果认为:送风速度增大时,车室内的温度普遍下降,流速增加;送风温度升高时,车室内流速的线型基本不变,温度普遍升高;送风倾角的变化对车室内空气的流动形式有较大的影响;送风口的位置改变对车室后部的温度场影响不大。送风速度过高或过低,各计算截面的ADPI指标都会偏低,送风速度增大时,各计算截面的速度、温度不均匀系数有所降低,但是幅度不大,所以没必要大幅度增加送风速度来追求较低的不均匀系数。送风温度的改变对于这Ⅲ平面和Ⅳ平两个平面的温度不均匀系数基本上没有什么影响。不同的送风角度对于Ⅳ平面的温度不均匀系数也影响不大。当车室内冷负荷减小时降低送风速度,或者稍微升高送风温度,不仅可以获得与全负荷下相类似的空调效果,还能有助于节省能源。 最后,提出了对进一步工作的展望。更多还原

【Abstract】 The thesis is based on Computational Fluid Dynamics (CFD), and a three-dimensional model of air-conditioning car is set up with a simplified vehicle compartment and RNG k - ε double-equation turbulent stream model. The corresponding boundary conditions of this issue are also established. In this way, a complete mathematical description and controlling equations of internal temperature and velocity field of air-conditioning car is available.The air current distribution in air-conditioning vehicle is compared and analyzed qualitatively and quantificationally about different air supply parameters, such as temperature, velocity, distribution angle and air vent position. With commercial software FLUENT as the operational platform, the outcomes of the velocity field as well as temperature field are obtained. The numerical results become visible and vivid with software TECPLOT. And the data is processed to get temperature coefficient of ununiformity, velocity coefficient ununiformity and air diffusion performance index. Thus the basis of the optimization can be provided.From the result, we can conclude: when the air supply velocity increases, the temperature will generally drops;when the air supply temperature increases, the speed of flow is basically invariable and the temperature generally elevates;the change of supply angle don’t have tremendous influence on the flow;and the air vent positions have no big influence on the temperature field of the rear compartment. If the air supply velocity is too high or low, the ADPI target of each computation section will be somewhat low. When the supply speed increases, the speed and temperature nonuniformity coefficient of each computation section will reduces, but the scope of reduction is not big. Therefore it is not necessary to increase blast speed by leaps and bounds to pursue lower nonuniformity coefficient. The change of the blast temperature basically has no influenceon the temperature nonuniformity coefficients of III and IV plane. Different supply anglesalso affect the temperature coefficient of IV plane slightly. When the cold shoulder reduce,it is wise to reduce the supply speed or elevate the supply temperature. It not only may obtain the similar air conditioning effect with the capacity load, but also can be helpful to save the energy.At last the future research on this subject is brought forward.更多还原