Vibration Analysis Of Turbine Set Under Partial Admission

Turbines are not only used as the engines of thermal power, nuclear power plants and geothermal power stations, but also used to drive pumps, fans, compressors and ship propeller. Because there is such a broad application of steam turbine, the security operation of steam turbine equipments has become a top priority, while the vibration level is one of the key indicators which direct reflect the safe operation of Unit, so it is very important to analyze the vibration of steam turbine.In this paper, the main job is modeling and simulating the vibration response of steam turbine under partial admission. According to the changes of different admission, there are five inlet conditions considered, and because the vibration of different positions of turbine set is not exactly the same, seven properties Location as test points are selected to analyze the vibration, including bearings, bearing bracket, shaft and so on.In this article, a modeling and simulation methods about vibration of the steam turbine under partial admission was proposed, and a effective measure to prevent the harmful vibration of turbine was proposed through spectrum analysis and comparative analyze the vibration of the steam turbine under different conditions.Firstly, three-dimensional finite element model was established along the steam turbine test-bed, solving the modal model, extracting and analyzing the natural frequencies and natural modes; Secondly, carrying out the exciting force of five conditions with Fourier transform and analyzing the harmonic components contained, loading the exciting force which was calculated by CFD software and resolving; Thirdly, analyzing(spectrum analysis) the test points'acceleration by MATLAB, comparing with natural frequencies and natural modes; At last, summed up a conclusion: It is easy to arose the resonance if exciting force contained harmonic components whose frequency is as same as the set's natural frequency; There is a relation between the vibration of turbine and the degree of imbalance of exciting force, the exciting force of steam turbine under two adjacent inlet channel admission is most unbalanced, the vibration is strongest; the exciting force of steam turbine under two diagonal inlet channel admission and full scale admission is most balanced, the vibration is weakest.At the same time, if the degree of imbalance of exciting force is same, the greater of the composition of exciting forces, the stronger vibration of turbine.