Rotordynamic Instabilities Caused by the Fluid Force Moments on the Backshroud of a Francis Turbine Runner
スポンサーリンク
概要
- 論文の詳細を見る
Severe flexural vibration of the rotor shaft of a Francis turbine runner was experienced in the past. It was shown that the vibration was caused by the fluid forces and moments on the backshroud of the runner associated with the leakage flow through the back chamber. The aim of the present paper is to study the self-excited rotor vibration caused by the fluid force moments on the backshroud of a Francis turbine runner. The rotor vibration includes two fundamental motions, one is a whirling motion which only has a linear displacement and the other is a precession motion which only has an angular displacement. Accordingly, two types of fluid force moment are exerted on the rotor, the moment due to whirl and the moment due to precession. The main focus of the present paper is to clarify the contribution of each moment to the self-excited vibration of an overhung rotor. The runner was modeled by a disk and the whirl and the precession moments on the backshroud of the runner caused by the leakage flow were evaluated from the results of model tests conducted before. A lumped parameter model of a cantilevered rotor was used for the vibration analysis. By examining the frequency, the damping rate, the amplitude ratio of lateral and angular displacements for the cases with longer and shorter overhung rotor, it was found that the precession moment is more important for smaller overhung rotors and the whirl moment is more important for larger overhung rotors, although both types of moment due to the leakage flow can cause self-excited vibration of an overhung rotor.
- ターボ機械協会、韓国流体機械学会、中国工程熱物理学会、国際水理学会の論文
ターボ機械協会、韓国流体機械学会、中国工程熱物理学会、国際水理学会 | 論文
- Prediction of Wear Depth Distribution by Slurry on a Pump Impeller
- Computational Investigations of Impingement Heat Transfer on an Effused Concave Surface
- Influence of Blade Outlet Angle and Blade Thickness on Performance and Internal Flow Conditions of Mini Centrifugal Pump
- Experimental Study on Surge Inception in a Centrifugal Compressor
- Erratum:Dynamic Analysis of Francis Runners - Experiment and Numerical Simulation[International Journal of Fluid Machinery and Systems Vol. 2 (2009) , No. 4 (October-December), pp.303-314]