Research On The Dynamic Characteristics Of Rotor Blade Based On LS-DYNA

Steam turbine is a turbo-machinery converted steam power into mechanical energy, is the most widely used in modern thermal power plant of the prime mover. The steam turbine is a aggregation of high and new technology in the integration of high-end machinery products. Blade is one of the key components of the steam turbine, also is the most delicate and the most important parts. According to statistics, the accident of steam turbine forced outage rate of 70% is associated with blade damage, blade accident losses more than half of all accidents. Analysis and inherent characteristics and dynamic characteristics of rotor blade, to improve the durability, reliability and life of the turbine, avoiding unnecessary personal security and economic loss caused by blade incident is very necessary, and has important engineering value.This paper mainly by using LS-DYNA software, based on contact-collision numerical calculation theory, implicit and explicit integral algorithm theory, and the large deformation dynamics theory, the inherent characteristics of turbine blade and blade-casing rubbing rule has carried on the comprehensive analysis and research.First, considering the influence of the blade rotation to soften and centrifugal players, grid density was studied under the condition of pre-stressed in LS-DYNA, researched the results influence on the blade natural frequency; Compared the natural frequency, vibration model between LS-DYNA and ANSYS, verified calculate the inherent characteristics of blade using LS-DYNA is correct; Calculates the natural frequency of the blades under different rotational speed, mapped the Campbell diagram, and get the resonance speed and resonance frequency, provides a theoretical basis for the safety assessment of vibration and further optimization of blade tissue structure.Secondly, research dynamic response of blade in the cases of blade-casing local rubbing. Established two local rubbing model of the blade-disc of geometric eccentric and elliptical casing, draw the rubbing force curve, dynamic stress curve, rubbing vibration attenuation frequency domain graph, displacement graph and contact interface energy change curve, analysis and contrast the two models of rubbing characteristic.Finally, study the blade-casing rubbing dynamic characteristics for the whole geometric eccentric blade-casing model. Simulated the rubbing process of blade-casing in the condition of casing elastic; Draw the blade dynamic stress curve, rubbing force curve, blade vibration attenuation curve of frequency domain and energy transformation curve of the contact interface, by all those graphs study dynamic characteristics of blade after blade-casing rubbing.