STV-13 Calculating Tube Vibration Amplitude

K. J. Farrell

Motivated by a significant number of false positive indications of tube vibration due to excessive crossflow amplitude, we reviewed current methods and explored the merits of a less conservative alternative acceptance integral approach for calculating tube vibration amplitude. Empirical random pressure power spectral density (PSD) and acceptance integral functions can be used to calculate the vibration amplitude for a tube excited by cross flow. Depending on the coherence length and the PSD of the excitation flow, the acceptance integral method is applicable to both turbulent buffeting and vortex shedding for bundle entrance tubes and tubes imbedded in the bundle. Using as an example a multi-span tube, we compared results for turbulent buffeting and vortex shedding among the acceptance integral approach, Xist, Xvib, TEMA, and other models in the literature. A comparison of vortex shedding amplitudes using the Xist 3.0 method and the TEMA method for the HTRI vibration data bank indicates that the latter is more conservative and slightly less accurate. Thus, our study affirms the Xist 3.0 methods for prediction of tube vibration amplitude due to vortex shedding and turbulent buffeting.