关键词: 汽轮机, 末级叶片, 振动特性, 振动试验

Abstract: A three-dimensional finite element model of last stage blades is constructed,and the static frequency and mode shape of the blades are analyzed.Then,the dynamic frequencies of the blades under pre-stressed conditions are calculated,and the effect of the operating speed on the vibration characteristic of the blade is investigated.Finally,the static frequency test,the dynamic frequency test and the vibration response test are conducted on a vibration test table.The results show that ( 1) the test results accord well with the model-simulated values; ( 2) the dynamic frequencies increase with the rotational speed,and they are greater than the static frequencies; ( 3) the rotational speed greatly affects the low-order frequencies; and ( 4) under the nine double frequency excitation of the rotational speed,a second-order resonance occurs,and the blades are more likely to suffer a fatigue failure.

Key words: steam turbine, last stage blade, vibration characteristic, vibration test