轴流式水轮机模型飞逸过程三维湍流数值模拟

通过作者建立的非稳态过程三维湍流数值模拟方法,模拟了轴流式水轮机模型飞逸过程,并进行了其三维数值湍流计算,获得了机组到达最大转速时所需时间、最大飞逸转速值、飞逸过程内特性流场演变规律以及转速、流量、力矩与测点静压随时间变化的曲线。计算结果表明,所得最大飞逸转速与试验值非常接近,误差在1.5%以内;所得力矩及流量等外特性参数变化过程均符合高比转速水轮机理论特性;当转速增大到某一数值之后,尾水管水力稳定性急剧恶化是引起机组振动的主因。

Three-dimensional CFD simulation of the runaway transients of a propeller turbine model

Three-dimensional unsteady CFD simulation method is established to simulate runaway transient of a propeller turbine model. Through three-dimensional turbulent numerical calculation, the spent time and the maximum runaway speed are attained while the generating unit enters runaway state, and the variation of inner flow and varying curves of unit rotate speed, flow rate and the static pressure of measuring points are revealed during the runaway transient. The numerical results of the propeller turbine model show that the maximum runaway speed agrees well with experimental data with error less than 1.5%, and the characteristic parameters vary according to the theoretical performance of high specific speed hydro turbine.Furthermore, flow stability deteriorates rapidly in the draft tube passage as the rotate speed increasing,which is the key source of unit vibration.