시뮬레이션에 의한 유체 유동 굴곡파이프의 지지점 변화에 따른 고유 진동수 고찰

A Simulation for the Natural Frequencies of Curved Pipes Containing Fluid Flow with Various Support Locations

A simulation is performed to investigate the effect of the pipe supports on the change of the natural frequencies of curved pipe systems containing fluid flow, for different elbow arigles and geometry of the pipe systems. Based upon the Hamilton’s principle, the equations of motions are derived, and the finite element equation is constructed to solve the corresponding eigenvalue problem. The angles of elbows do not affect the change of the fundamental natural frequency, but affect the change of the third or higher natural frequencies. Without any support, the change of the fundamental natural frequency due to the geometric change is smaller than the change of the second or higher natural frequencies. The more curved parts exist in the pipe system, the less change of lower frequency range, compared with the change of higher frequency range, is observed. Spring supports can be used to reduce the fundamental natural frequency, without change of the second or higher natural frequencies. To avoid resonance, which is critically dangerous from the view point of structural dynamics, the mechanical properties such as stiffness or the location of pipe supports are need to be changed to isolate the natural frequecies from the frequency range of dominant vibration modes.