船用燃气轮机变几何动力涡轮大攻角流动特性的三维数值模拟

采用三维数值模拟技术，研究了可调导叶转动导致变几何动力涡轮气动性能变化的流场机理。结果表明，在较小的转角范围内，采用大转折角设计的可调导叶使涡轮处于大攻角运行。在大正攻角或大负攻角下可调导叶级动叶栅流道内的三维分离流场结构及其产生机理有很大差异，而且大正攻角造成的吸力面分离流动更使整个涡轮的效率显著地下降。通过系统的机理分析，提出可调导叶宜采用较小转折角的后部加载叶型，而变几何动力涡轮可调导叶级动叶栅要采用较大负冲角的气动设计原则。

Three-dimensional Numerical Simulation of the Flow Characteristics at a Large Incidence of the Variable-geometry Power Turbine of a Marine Gas Turbine

By employing three-dimensional numerical simulation techniques a study was conducted of the flow field mechanism of the aerodynamic performance variation of a variable-geometry power turbine caused by the rotation of adjustable guide vanes. The results of the study indicate that within a range of relatively small turning angles the adjustable guide vanes designed by using a large turning angle will enable the turbine to operate at a large incidence.The three-dimensional separation flow field structure and its generation mechanism in the rotating cascade flow channel of an adjustable guide vane stage at a large positive incidence are very different from those of the same vane stage at a large negative incidence.Moreover,the suction-surface separation flow caused by a large positive incidence will significantly reduce the efficiency of the turbine as a whole.Through a systematic mechanismic analysis the authors have proposed the use of a rear loaded blade profile for the adjustable guide vanes using a relatively small turning angle and the adoption of an aerodynamic design principle under which a relatively large negative incidence is employed for the rotating cascade of the adjustable guide vane stage of the variable-geometry power turbine.