透平静叶栅中间叶高处水滴尺寸测量及临界韦伯数分析

通过测量获得了多种工况下试验透平叶栅进出口平均叶高处可能带来水蚀危害的水滴的尺寸,揭示并分析了静叶栅后水滴尺寸比叶栅前大大减小且水滴平均直径随气流流速增大而减小的原因。结合试验测试数据和对叶栅尾迹区气相流场的数值模拟结果,更精确地推算出了静叶尾迹区粗大水滴形成二次雾化的临界韦伯数范围,建议取为20。提供了一个推导临界韦伯数的详细示例。由于试验条件更接近实际汽轮机,所得汽轮机湿蒸汽级内的水滴尺寸及分析获得的临界韦伯数更加确切和可靠。这些都有助于更准确地预测叶片的水蚀和选择合理的防水蚀措施。图7参6

Measurements of Droplet Sizes at Mid-hight of Stationary Turbine Blades and Analysis of the Critical Weber Number

Measurements under various conditions at blade mid-hight of a testing turbine cascades inlet and outlet revealed the water droplet sizes that may cause erosion. Reasons are analyzed why droplets behind the static cascade are much smaller than those in front and why the average droplet size decreases with increasing flow velocity. Leaning on experimental data and numerical simulation results of the gas phase flow field in the cascade's wake, the range of the critical Weber Number (for which We_ cr=20 is suggested) of secondary atomization of coarse water droplets in the static cascade's, wake has been calculated with improved accuracy, and an example shows of how the critical Weber Number is being obtained. Since the experiments are quite close to actual steam turbine conditions, the droplet sizes obtained in wet steam turbine stages and the critical Weber number determined by analysis are much more realistic and credible. All this is helpful for more accurate prediction of blade erosion, and for choosing reasonable measures of prevention. Figs 7 and refs 6.