Newmerical Analysis of Dynamic Characteristics of600MW Superctritical Steam-Turbine Shaft
|School||North China Electric Power University|
|Course||Mechanical and Electronic Engineering|
|Keywords||Supercritical Steam Turbin Unit Transfer Matrix Method CriticalSpeeeds and Vibration Modes Unbalance Response Rubbing|
Supercritical technique is a developing thermal power technique in the world because of its lower fossil material consuming. And will be the trend of future development. But the supercritical units have complexd structure and higher working parameters. So its conditions are relatively complexed. In order to ensure its secure and steady operation, we should know its dynamics clearly.This paper takes an600MW supercritical steam turbine unit as an object, mainly analyzes its critical speeds, vibration modes, and makes numerical simulation of its unbalance and rubbing vibration. First of all, a dynamic model for the rotor system is established with lumped parameter method. It is to descrete the shafting to a multi-degree of freedom system with several lumped masses and mass-less elastic shafts with uniform cross-section. The dynamic characteristics of oil film of the supported bearing is always simplified with four stiffness coefficients and four damping coefficients. Secondly, the critical sppeds and vibration modes of the steam turbin are calculated based on the Prohl and Riccati transfer matrix method. In order to discuss the influence of supporting form to the natural characteristics of rotor system, the critical speeds of the system under isotropic and anisotropic supported are calculated in this paper. Also, the effect of bearing stiffness and daming and the working temperature on rotor’s critical speeds are discussed here. Thirly, the unbalance response of the rotor system is calculated by a numerical analysis method of Riccati transfer matrix method. It is to assume an unbalance value at the rotor syetem and calculate its response under different coditions, including response for rotor at the different unbalance places under working rotating speed, and response for rotor at different rotating speeds while the unbalance value is at an fixed place. At last, the rubbing response of high and intermediate pressure rotor is calculated by Newmark method. Response under differeng rubbing force is discussed. The aim of these work is to provide some help for condition monitoring and fault diagnosis of the supercritical units.