Damping ratio and excitation force of a vibrating tube in two-phase flow

This paper deals with the mechanism of damping and excitation force acting on a vibrating tube in two phase flow. The gas phase flows faster than the liquid phase in two phase flow. This relative velocity can cause turbulence and momentum diffusivity which induce pressure fluctuation and additional viscosity. The investigation of the relationship between tube vibration and two-phase flow showed that damping ratio and excitation force are closely related to the drift flux of the gas phase. From these results it was found that damping ratio ζ is given by ζ ∝ ρL(1-α) √jGL, and excitation force √Φeq is by √Φeq ∝ ρL (1-α)jGL, where, ρL is liquid density, α is void fraction, jGL is drift flux.