启动过程压缩空气储能向心涡轮三维流动特性研究

Three Dimensional Flow Characteristics of a Radial Inflow Turbine in Compressed Air Energy Storage System During Start-Up Process

为研究压缩空气储能系统的向心涡轮启动过程内部流动损失特性,采用全三维计算流体动力学(CFD)模型对其启动过程进行了数值模拟,与实验结果对比表明,虽然该模型在启动初始阶段与转速稳定阶段存在一定误差,但仍能够整体上反映启动过程的效率变化特征。在此基础上,进一步分析了启动过程中动叶通道内损失区及流场变化特征,结果发现,动叶进口攻角是影响内部流场主要因素:在启动初始阶段,叶轮进口攻角较大,动叶载荷集中在叶片前缘,形成明显的通道分离涡与前缘涡;在快速启动段,攻角减小,动叶载荷沿弦长分布更为均匀,通道分离涡及前缘涡逐渐减小并向叶片吸力面迁移。在整个启动阶段,动叶通道内高损失区也随着通道分离涡逐渐迁移且变小,并向相邻叶片吸力面集中。

To study the internal flow loss characteristics of the radial inflow turbine in Compressed Air Energy Storage(CAES)system during start-up process,a full three-dimensional Computational Fluid Dynamics(CFD)model was established to simulate the flow field of CAES radial turbine during start-up,and the results were also validated with the experiment.It can be found that the numerical simulation results of total-to-total efficiency are basically in well agreement with the experimental results in trend,although the deviation only occurs in the initial and stable speed stages of the start-up process.Furthermore,the loss area and flow structure in the rotor passage during start-up process were also analyzed.The results show that the rotor inlet angle of attack is the main factor affecting the internal flow field:in the initial start-up stage,higher rotor inlet angle of attack increases the blade load near the leading edge of the blade resulting in obvious passage separation vortex and leading edge vortices;in the fast start-up stage,the attack angle is decreased,and the distribution of the rotor load is more uniform along the chord length.The passage separation vortex and leading edge vortices thus gradually decrease and migrate to the suction surface of the blade.During the whole start-up process,the high loss area in the rotor passage is also reduced and gradually moves to the suction surface of adjacent blades with the passage separation vortex.