高位布置H级燃机基础多点位移SRSS法可靠概率研究

Research on Reliability Probability of SRSS Method for Multi-Point Displacement of Foundation of H-Class Gas Turbine in High Position

[目的]大型H级燃机基础通常具有多个扰力作用,并采用平方和开平方根(SRSS)法求得质点的振动位移。但SRSS法求得的振动位移并不是可能发生的最大位移。文章旨在分析所有可能出现的振动位移,研究SRSS法的可靠概率。[方法]建立了高位布置H级燃机基础的三维有限元模型,通过多质点分别施加单向扰力分析,采用SRSS法计算质点振动位移;提出采用多质点分别施加双向扰力,由于各质点动扰力之间角度的不确定,采用线性叠加法计算所有可能的振动位移并统计其概率分布。[结果]H级燃机基础质点10在40.75 Hz横向振动位移SRSS法组合值为16.40μm,最大可能横向振动位移值为24.18μm,SRSS法的可靠概率约为50%。[结论]基于SRSS法获得的多质点振动位移值并不是最大值,其具有一定的可靠概率,对于特别敏感或者重要的动力基础分析中宜控制其可靠概率,可采用增大裕度的方法来提高其可靠概率。

[Introduction]The foundation of a large H-class gas turbine usually has multiple disturbing forces, and the vibration displacement of the mass points is obtained by the square root of the sum of the squares(SRSS) method, but the vibration displacement obtained by the SRSS method is not the maximum possible displacement. The research aims to analyze all possible vibration displacements and study the reliability probability of the SRSS method. [Method]A three-dimensional finite element model was established for the foundation of a H-class gas turbine in high position, the unidirectional disturbing forces separately applied on mass points were analyzed, and the vibration displacement of the mass points was calculated by the SRSS method. It was proposed to apply the bidirectional disturbing forces on the mass points separately. Considering the uncertainty of angle between the disturbing forces at the mass points, the linear superposition method was used to calculate all possible vibration displacements and analyze their statistical probability distribution. [Result]The combined value of the lateral vibration displacement of mass point 10 of the H-class gas turbine at 40.75 Hz by the SRSS method is 16.40 μm, and the maximum possible lateral vibration displacement value is 24.18 μm. The reliability probability of the SRSS method is about 50%. [Conclusion]The multi-point vibration displacement value obtained based on the SRSS method is not the maximum value, and the method has a certain reliability probability. For particularly sensitive or important dynamic foundation analysis, the reliability probability of the method should be controlled, and it can be improved by increasing the margin.