Scroll compressor is a key component of the air conditioner/heat pump system in electric vehicle. This paper focuses on the impacts of discharge port design on the transient performance and flow mechanism of the scroll compressor. A three-dimensional unsteady computational fluid dynamic model is established and validated. The computational domain includes inlet duct, scroll working chamber, discharge port, check valve, plenum chamber and outlet duct. R134a is used as the working fluid. The impacts of the position of the conventional circular port on the transient characteristic and flow loss mechanism of the scroll compressor are studied. It is found that large pressure difference between the two central chambers is resulted from discharging time difference of the two chambers. It inevitably leads to under compression in downside chamber and over compression in the upside chamber at designed condition. The conventional circular discharge port cannot address this problem. Therefore, a novel discharge port with a tail is proposed to retard the discharge time of the downside chamber and advance that of the upside chamber. It is found that the isentropic efficiency of the scroll compressor is improved by 2.4%. The maximum pressure unbalance between the upside chamber and downside chamber is reduced by 50%.

涡旋压缩机是电动汽车空调/热泵系统的关键组件。本文重点研究排出口设计对涡旋压缩机瞬态性能和流动机理的影响。建立并验证了三维非定常计算流体动力学模型。计算域包括入口管道，涡旋工作室，排出口，止回阀，增压室和出口管道。R134a用作工作流体。研究了传统圆形端口的位置对涡旋压缩机瞬态特性和流动损失机理的影响。发现两个中央腔室之间的大压力差是由于两个腔室的排出时间差引起的。在设计条件下，它不可避免地导致下腔室中的压缩不足和上腔室中的过度压缩。传统的圆形排出口不能解决这个问题。因此，提出了一种新型的带有尾部的排出口，以延迟下腔室的排放时间并提前上腔室的排放时间。发现涡旋压缩机的等熵效率提高了2.4％。上部腔室和下部腔室之间的最大压力不平衡减少了50％。发现涡旋压缩机的等熵效率提高了2.4％。上部腔室和下部腔室之间的最大压力不平衡减少了50％。发现涡旋压缩机的等熵效率提高了2.4％。上部腔室和下部腔室之间的最大压力不平衡减少了50％。