随着节能降耗成为当今世界的迫切需要，提高通风机能量转换效率越来越受到重视，已成为通风领域内关键问题。掌握叶轮内不可逆能量损失演化机制是实现能量高效转化的前提与基础，但目前尚缺乏针对叶轮内不可逆能量损失机理方面的研究。为此，以对旋轴流通风机为研究对象，采用数值模拟和实验方法获得了不同流量工况下通风机内部流场。基于熵产理论，建立了通风机叶轮内不可逆能量损失理论模型，明确了叶轮内不可逆能量损失与空间流场参数的内在关系，实现了叶轮内不同类型能量损失的定量分析，结合叶轮内流动特征，明确了能量损失空间演化规律和产生原因。研究结果表明，熵产方法计算叶轮内不可逆能量损失是可靠的，直接黏性耗散损失和壁面摩擦损失是能量损失的重要组成部分，而湍流耗散则是引起能量损失的主要原因，达到总能量损失的60%～80%；对于前级叶轮，湍流耗散引起的能量损失在1.0Q_BEP流量工况(Q_BEP为最优工况流量)达到最小，而后级叶轮能量损失随流量的降低而增大。能量损失主要集中在Span=0.6～1.0 (Span为叶展方向轮毂至机壳的无量纲距离)区域，在1.0Q_BEP工况达到总能量损失的70%；叶顶间隙泄漏流和叶片前缘溢流引起的螺旋旋涡、叶轮内回流、叶片压力面和吸力面流动分离以及叶片后缘尾迹都将导致能量损失产生，其中流动分离和尾迹引起的高能量损失区域较小，能量损失相对有限，而旋涡和回流显著影响叶轮内流体流动，最终导致叶顶附近区域出现大量能量损失。

With the urgent need of energy saving and consumption reduction in today's world, the topic of increasing the energy conversion efficiency of ventilation fans has been attracted a lot of attentions, it has become a key issue in the field of ventilation. The understanding on the evolution mechanism of irreversible energy loss in impeller is the premise and basis for realizing the efficient energy conversion of ventilation fans. At present, the irreversible energy loss mechanism in impeller is still lack of research. Therefore, the internal flow field of the contra-rotating axial fan at different flowrates is obtained by numerical simulation and experimental methods. A theoretical model of irreversible energy loss in impeller of ventilation fans is established based on entropy production theory, and the relationship between the irreversible energy loss in impeller and the flow field parameters is clarified. A quantitative analysis is conducted on different types of energy loss in impeller, and the spatial evolution law and causes of energy loss are clarified by combining with the flow characteristics in impeller. The results show that the entropy production method is reliable in calculating the irreversible energy loss in impeller. Direct viscous dissipation loss and wall friction loss are important components of energy loss, while turbulent dissipation is the main cause of energy loss, accounting for 60% to 80% of the total energy loss. For the front impeller, the energy loss caused by turbulent dissipation reaches the minimum at 1.0 Q_BEP, while the energy loss of the rear impeller increases with the decrease of flowrate. The energy loss is mainly concentrated in the region of Span=0.6−1.0, reaching 70% of the total energy loss at optimal flow condition. The spiral vortex caused by blade tip leakage flow and overflow of blade leading edge, backflow in impeller, flow separation at blade pressure and suction surface, and blade trailing edge wake will cause energy loss. The high energy loss region caused by flow separation and wake is relatively small, and the energy loss is relatively limited. However, the vortex and backflow significantly affect the flow in impeller, ultimately leading to a significant energy loss in the region near the blade tip. The research results can provide a reference for the evaluation of irreversible energy loss of ventilation fans.