Effect of Galerkin Modal Truncation on Natural Frequency Analysis of Cantilevered Pipe Conveying Fluid
QI Huan-huan1;XU Jian2
1. Nuclear Power Institute of China, Chengdu 610041, China; 2. School of Aerospace Engineering and Mechanics, Tongji University, Shanghai 200092, China
Abstract：: Two methods, Galerkin method and complex mode method, are developed to analyze natural frequency character of cantilevered pipe conveying fluid system at different flow rate. The influence of Galerkin modal truncation to natural frequency results is analyzed. Firstly, complex mode is used in a simplified cantilevered system, then the complex transcendental equations are solves by secant method, and the natural frequencies are obtained as flow rate varying. Secondly, the first N-order natural frequencies can be obtained approximately by Galerkin method which discretizes partial differential equations into ordinary differential. Finally, comparing the results that obtained by two methods, we can found that a sufficient exact appropriate model can be build by Galerkin method truncating appropriate mode, what facilitates control system designing and engineering practice.
2011, Vol. 30 
