工业汽轮机补汽结构对压力损失的影响及优化
Optimization Design and Pressure Losses of Steam Admission in Industrial Steam Turbines Depending on Geometrical Parameters

为改进工业汽轮机补汽结构的性能,应用ANSYS？？CFX软件、以SST？？RM湍流模型对流体混合产生的总压损失进行了详细研究,分析了结构参数对总压损失的影响,得出在不同流量比下,支流以60°夹角进入主流,或者过渡段为圆角时,T型通道具有较低的总压损失。在此基础上,优化设计了一种截面为椭圆形且沿周向截面面积渐缩的补汽结构,优化后的补汽结构能够有效控制补汽沿周向的密流分布及混合蒸汽的流动方向,由此提高了整机性能。研究结果表明:补汽流动方向与主流方向的夹角对流场有较大影响,优化结构的总压损失系数在各工况下至少降低30％;截面形状与截面面积变化对补汽的周向扩散有较大影响,截面为椭圆形且截面面积沿周向渐缩时补汽结构能够提高密流周向分布的均匀度;采用混合总压损失系数和标准偏差能够有效评估补汽性能。
To improve performance of steam admission geometry in industrial steam turbine, the total pressure loss of the mixing flow are investigated with ANSYS？？CFX and the effects of admission geometry parameters on the total pressure loss are evaluated by SST？？RM. For a T typed passage, as the branch flow jets into the main stream at angle of 60° or the connecting part is set as rounded corner, the total pressure loss gets lower at different flow rate. Analyzing the total pressure loss coefficient of the T typed passage in the flow field, a new admission with elliptical and gradually converging sections along the circumferential direction is designed, and the optimized structure can effectively control the admission mass flow distribution and the flow direction, which makes the admission density flow more uniform along the circumferential direction to improve the performance of the whole steam turbine. Under the same condition, when the angle between the admission steam flow and main flow is taken as about 60°, the total pressure loss can be reduced by more than 30％ compared with the case of 90°. The admission structure with elliptical cross section is beneficial to improve the uniformity of density flow distribution along the circumferential direction. The mixing total pressure coefficient and the standard deviation are suggested to effectively evaluate the admission performance