某船用汽轮机复速级流场特性分析

Analysis of Flow Field Characteristics in the Complex Stage of a Marine Steam Turbine

运用ANSYS CFX软件对某型船用汽轮机复速级进行数值模拟,模拟结果表明:在承担极大焓降的复速级内,钻绞式喷嘴出口的超音速汽流在第一列动叶的前缘背弧区域产生激波,波后汽流温度、压力升高,在背弧前缘区域形成局部附面层卷吸,波后汽流在动叶后部形成的缩放流道内继续加速,在背弧局部区域出现附面层分离,汽流继而在转向导叶内加速,在前缘区域形成普朗特迈耶波,波后的亚音速汽流在中部区域形成较大的涡流分离,分离涡并未向后部扩展而是继续加速;在第二列动叶内加速,前缘继续形成普朗特迈耶波,波后在背弧中部区域出现壁面分离,并在后半区域主流区逐步扩展沿伸,直至叶片尾缘区域,进一步增大了整级的能量损失,严重影响了该级的汽动性能。

ANSYS CFX fluid software is used for a certain type marine steam turbine stage is simulated,the simulation results show that taking large enthalpy drop Curtis level,steam drill ground type nozzle export of supersonic flow in the first column moving blade leading edge back arc area produce shock wave,wave after the steam flow temperature,enthalpy,pressure,formed in back arc front area local entrainment boundary layer.The steam flow behind the wave continues to accelerate in the scaling passage formed by the rotor blade passage,and local boundary layer separation occurs in the latter part of the back arc.Steam flow and in turn guide blade continues to accelerate,formed in the frontal area prandtlmeyer wave,wave of subsonic gas flow in the central area of the blade after form a larger vortex separation,the separation vortex did not expand to the rear,but continued to accelerate,steam flow in the second column inside the rotor speed,leading edge continue to form the prandtlmeyer wave,wave after the wall began to appear in the central back arc area separation.In the latter half of the stage,the main flow area gradually extends to the trailing edge of the blade,which further increases the energy loss of the whole stage and seriously affects the aerodynamic performance of the stage.