Abstract Firstly, the shafting of vertical pumping units is simplified as a geometric model with three bearings and two discs in this paper. Motion equations of the central trajectory for electromotor rotor and pump runner are established. And then, analytical expressions of central trajectory under steady state are obtained. Secondly, according to particularity of no-water start test and approximate treatment, calculation methods of the natural frequency and damping ratio for electromotor rotor and pump runner are proposed based on some of approximate assumptions. Using test data under no-water start test in a pump station, one fits to obtain the throw shape of shafting referring to geometric structure of shafting, and obtain throw data of runner and rotor by using the polynomial fitting method. Characteristic parameters of water pump units can be calculated by using throw data of runner and rotor, in which detailed calculation steps and explanation are given. The proposed method can calculate characteristic parameters of shafting vibration, such as natural frequency, damping ratio and mass eccentricity, and calculation results have a certain numerical stability. Owning to the test data used in calculation, the obtained characteristic parameters of shafting vibration include uncertainty factors produced by install and debug. So results are of reference value to the research into vibration characteristic of water pump units installed under operation.
LI Yao-Hui-1,ZHU Shuang-Liang-2. Calculating characteristic parameters of water pump shafting based on data under no-water start test[J]. Journal of Drainage and Irrigation Machinery Engin, 2017, 35(8): 659-.