Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays

The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model is developed and utilized to study the triangular tube patterns. The developed mathematical model is tuned with the experimentally measured fluid-elastic force coefficients. An experimental setup with water channel and instrumented test section is constructed. In this investigation, two test sections are constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized for predicting the critical flow velocities at the inception of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations, namely the square and rotated square arrays. The results of the two tube patterns are viewed in light of TEMA predictions. The comparisons demonstrated that TEMA predictions provided more conservative guidelines for all the configurations considered. Field application of the obtained results was successful in extending the service life of tube and shell heat exchangers beyond that predicted by TEMA.