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推导了开度不变、转速不变和出力不变、转速不变两种运行条件下水轮机水力阻抗计算公式,分析了这两种运行条件下机组水力阻抗的差异,指出在混流式水轮机运行范围内,在前者条件下机组水力阻抗大于0,在后者条件下机组水力阻抗小于0.通过理论分析和数值计算相结合的方法,研究了机组水力阻抗对水电站有压输水系统自激振动特性的影响.研究表明:机组水力阻抗的正负决定了系统衰减因子的正负及大小,对系统频率的奇偶性具有选择性.
The hydraulic impedances calculation formula of hydraulic turbine under the two operating conditions of constant opening, constant rotational speed and constant output speed is deduced. The differences of hydraulic impedances of the two operating conditions are analyzed. It is pointed out that in the operating range of Francis turbine, , The hydraulic resistance of the unit under the former condition is greater than 0, and the hydraulic resistance of the unit under the latter condition is less than 0. The self-excited vibration characteristics of the pressurized water delivery system of the hydropower station are studied by combining the theoretical analysis and numerical calculation. The research shows that the positive and negative of the hydraulic impedance of the unit determines the positive and negative of the system attenuation factor and the size of the system, and is selective to the parity of the system frequency.