列车车厢内气流分布的数值计算与测定

Numerical Calculation and Measurement of the Airflow Distribution in Air-conditioned Coach

针对车厢内温度分布不均匀问题,就列车空调设计工况进行数值计算,从理论上得到设计工况下车内气流分布情况。以一节硬卧车厢为研究对象,运用不可压缩流理论建立了车内气流的连续微分方程、动量微分方程和能量微分方程。采用k ε封闭模型,并用半隐式压力 速度耦合即SIMPLE算法计算出车内的速度场和温度场。实验测定空态下车内的气流分布,与数值计算值基本吻合,用数值解代替分散的、有限的实验测点值来进一步分析车内的热舒适性。通过计算分析得出:车厢内的平均风速为0 42m·s-1,处于铁规限定的上限,即车内速度偏高;铺位区和走廊区的平均温度分别为24 4℃和26 8℃。宽度方向上的温度不均匀性为0 75℃·m-1;采用人体热舒适性指标PMV得出特征断面上各铺位上达到热舒适标准的测试点仅为42%。

The temperature inside the railway coach is not evenly distributed. The numerical calculation of the designed working condition is made and the theoretic airflow distribution obtained. With one hard berth sleeper as a study object, the paper uses incompressible airflow theory and establishes the continuous differential equation, the momentum and energy differential equations of the airflow in the said coach. The velocity and thermal distribution of the air in the sleeper are obtained by the kε closure model and coupld with the SIMPLE (Simi Implicit Method Pressure Linked Equation) code to calculate the velocity field and the temperature field. Experiments of the airflow in an empty sleeper are carried out. The experiment results basically conform to the calculation. The numerical results can take the place of the sporadic, limited values in further analysis of the thermal comfort quality. Through the calculation, it is concluded that: the average airflow velocity in the carriage is 042 m·s-1 and stays at the upper limit of the MOR criterion, which means the velocity in the train is a litter higher. The average temperature in the berth area and aisle area is 244℃ and 268℃,respectively. The uneven temperature ratio over the width of the carriage is 075℃·m-1. By thermal comfort index PMV, the thermal comfort ratio of the specific profile at each berth is only 42%.