透平级三维粘性非定常流动和气流激振力的研究

Research on Three Dimensional Viscous Unsteady Flow and Excitation Force of Turbine Stage

针对非定常流动对透平气动性能的影响和导致产生动叶片振动疲劳的气流激振力,深入研究和总结了国内外透平机械的非定常流动,阐述了RNGk-ε湍流模型和双时间步法,并提供了笔者研究的2个汽轮机高压级以及末级的非定常流场与气流激振力的例子.结果表明:采用RNGk-ε湍流模型和双时间步法对透平级进行非定常粘性流场分析可获得更为详细、精确的流场状况以及更为真实的效率;气流激振力和激振力因子的水平与流场状况有密切联系,影响流场的因素(如背压,流量,动静间隙等)发生变化会对气流激振力因子产生影响.此外,还提出了今后进一步研究的思路和方法.

Aimed at the effect of unsteady flow on turbine aerodynamic characteristics and the induced excitation force causing blade vibration fatigue, the research on unsteady flow in turbomachinery, conducted domestically and abroad, was widely reviewed and summarized. RNG k-e turbulence model and dual time step method were described. Two examples, studied by the writers, for unsteady flow and excitation forces analysis on high pressure and last stages of two steam turbines were provided. Results show that a more detailed and accurate flow field and a more realistic efficiency can be obtained through analysis of unsteady flow field by adoption of RNG k-ε turbulence model and dual time step method; And there exists a close relation of flow excitation force and excitation force level with the status of the flow field. When the factors affecting （such as back pressure, flow rate and clearance between nozzle and blade） change, it will impact on the flow excitation factors. At last, the ideas and methods for further studies were proposed by the writers.