高速水力负载是大功率燃气轮机、蒸汽动力性能测试的关键设备,其内部非定常流动是影响高速水力负载稳定运行和使用寿命的主要因素。本文基于CFD数值计算技术,对一多孔式转子高速水力负载非定常内流及空化流动特性进行研究。转子内部非稳定流动主要取决于最外层孔内流动,明显的高速区和低速区同时存在于尺寸较小的过流孔中,造成激烈的涡流运动,诱发明显的涡激作用。转子和定子间动静干涉区的脉动压力是流激振动的激励源,其时域峰、谷幅值受到转子外侧多孔结构的影响,脉动最大幅值的频域与轴频相关。空化现象发生在末端转子和中间转子最外层的过流孔中。空泡的发展和破灭会造成孔内流动的不稳定性,诱发剧烈的激励作用,影响机组的稳定运行。

Hydraulic dynamometer is the key equipment to measure the dynamic performance of high-power gas turbines and steam. Its internal unsteady flow is the main factor affecting the stable operation and service life of High-speed dynamometer. In this paper, based on CFD numerical calculation technology, the unsteady internal flow and cavitation flow characteristics of a porous rotor with High-speed dynamometer are studied. The unsteady flow inside the rotor mainly depends on the flow in the outermost hole. The obvious high-speed zone and low-speed zone exist in the small-sized flow hole at the same time, causing intense vortex motion and inducing obvious vortex-induced effect. The fluctuating pressure in the dynamic and static interference zone between the rotor and the drainage ring is the excitation source of the flow-induced vibration. The peak and valley amplitudes in the time domain are affected by the porous structure outside the rotor, and the frequency domain of the maximum amplitude of the fluctuation is related to the shaft frequency. Cavitation occurs in the outermost flow hole of the end rotor and the middle rotor. The development and collapse of the cavitation bubble will cause the instability of the flow in the hole, induce severe excitation, and affect the stable operation of the unit.