核电超长末叶气动稳定性的流固耦合数值研究  

Numerical Study on the Aerodynamic Stability of Super-Long Last-Stage Blades of a Nuclear Turbine Using Fluid-Structure Coupling

作　　者：庾明达 徐自力[1,2] 范志飞[3] 曹守洪[3] 范小平[3] 方宇[3] YU Mingda;XU Zili;FAN Zhifei;CAO Shouhong;FAN Xiaoping;FANG Yu(School of Aerospace,Xi＇an Jiaotong University,Xi＇an 710049,China;State Key Laboratory for Strength and Vibration of Mechanical Structures,Xi＇an Jiaotong University,Xi＇an 710049,China;Dongfang Turbine Co.Ltd.,Dongfang Electric Corporation,Deyang,Sichuan 618000,China)

机构地区：[1]西安交通大学航天航空学院,西安710049 [2]西安交通大学机械结构强度与振动国家重点实验室,西安710049 [3]东方电气集团东方汽轮机有限公司,四川德阳618000

出　　处：《西安交通大学学报》2018年第7期101-107,共7页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(51675406)

摘　　要：为了准确模拟内流场长叶片在高背压条件下的气动特性和稳定性机制,采用三维时域响应流固耦合算法进行了研究。流场域先进行内部迭代收敛后,在时域上与固体域进行耦合迭代求解,并且利用流场与叶片有限元模型之间的交界面进行气动力、位移等变量的数据交换和迭代计算,对新开发的核电超长末级叶片在3 600、7 200、10 800Pa这3种背压工况下的气动稳定性和流动特征进行了分析。结果表明,随着背压增大,在叶栅流道内的近出口处附近出现了由压力扰动引起的旋涡流动现象,3种背压工况下叶片的时域响应曲线均以1阶动频模态为主进行自由衰减,并表现出非线性的振动特征,叶片的响应幅值均呈现收敛的趋势,新开发的核电超长末级叶片在背压从3 600增大到10 800Pa范围内时保持气动稳定,不会发生颤振现象。叶栅背弧面激波随背压升高不断朝气流方向移动但并未发生脱体,在叶片振动过程中叶高各截面的流场流动也保持平稳,同时,时域响应曲线的气动阻尼随背压变大而减小,这表明叶片的气动稳定性随背压增加而逐渐减弱。A 3-D time-domain fluid-structure coupling method is adopted to analyze the aerodynamic characteristics of super-long last-stage blades of a nuclear turbine.In every time step,the variables like pressure and displacement are exchanged and calculated at the interface of the fluid-structure finite element model until convergence.The aerodynamic stability and flow behaviors of super-long last-stage blades of a newly developed nuclear turbine under three backpressure operations（3 600,7 200 and 10 800 Pa）were analyzed.Results showed that as the backpressure increases,eddies occur near the exits of the cascades due to the pressure disturbance.The amplitudes of blade response are all freely attenuating with the first-order natural frequency of the rotor blade in three different backpressure working operations.Besides,nonlinear features are caught within the oscillations,indicating that the newly developed turbine blades can maintain aerodynamically stable and there is no sign of flutter in the range from 3 600 Pa to 10 800 Pa.The shock waves on the suction side move upstream with the back pressure rise but they do not detach and the flows keep smooth when the blades are vibrating,which may be the cause of the aerodynamic stability of the blades.However,it is found that the aerodynamic damping reduces gradually,that is to say,the aerodynamic stability weakens with the rise of the backpressure.

关 键 词：核电超长末级叶片 三维流固耦合 时域响应 气动稳定性 

分 类 号：O323[理学—一般力学与力学基础]