CAJ | 학술논문

采用三维数值模拟方法，对带有过渡段和后机匣支板的低压涡轮进行全环非定常数值模拟，分析了各个叶片排流场中存在的非定常扰动及扰动源，研究了低压涡轮第二级中存在的多种扰动源叠加现象，并对流场中的静压波动进行了频谱分析。结果显示，过渡段的二次流对低压涡轮内部流场存在明显扰动，并向下游传播至涡轮出口。第二级动叶中，上游导叶通过频率与过渡段二次流自身脉动频率产生叠加，形成的新扰动频率为两者产生的差频。采用全环非定常数值模拟预测多级低压涡轮内部流动中存在的各种扰动频率及其相互叠加很有必要。
채용삼유수치모의방법，대대유과도단화후궤갑지판적저압와륜진행전배비정상수치모의，분석료각개협편배류장중존재적비정상우동급우동원，연구료저압와륜제이급중존재적다충우동원첩가현상，병대류장중적정압파동진행료빈보분석。결과현시，과도단적이차류대저압와륜내부류장존재명현우동，병향하유전파지와륜출구。제이급동협중，상유도협통과빈솔여과도단이차류자신맥동빈솔산생첩가，형성적신우동빈솔위량자산생적차빈。채용전배비정상수치모의예측다급저압와륜내부류동중존재적각충우동빈솔급기상호첩가흔유필요。
Three dimensional numerical simulations are conducted to investigate the unsteady flow field in a full scale low pressure turbine with intermediate turbine duct and rear casing. Several perturbations and their sources in each blade passage are analyzed, and the pressure fluctuation of flow field where monitoring points located is investigated with frequency analysis. Disturbance sources’frequency superposition is also introduced. Numerical results show that perturbation developed by secondary flow from intermediate tur-bine duct and propagated to the outlet is obvious in the flow filed. In the rotor field of the second stage, the upstream vane passing frequency and inherent frequency of secondary flow from intermediate turbine duct are stacking and a new disturbance frequency is formed. For accurately predicting the perturbations and fre-quency superposition phenomenon of unsteady flow in a multistage low pressure turbine, it is necessary to investigate the flow field with full scale simulation.