换热直管内外流诱导振动频率漂移特性

采用二维圆柱绕流模型,得到换热直管在较大范围雷诺数的横掠外流场作用下的升力和阻力函数,将其作为激励,同时考虑管道在非定常流动中的附加质量,建立了一种改进的内外流固耦合计算模型.计算结果表明:横掠外流带来的附加质量会导致管道固有频率的漂移,雷诺数也会影响外部激励的频率.由于内流雷诺数也会影响管道的固有频率,因此在特定的内外流共同作用下管道可能发生共振.本模型可以预测发生共振时内外流雷诺数的范围,为合理设置内外流的安全运行工况提供理论依据.

Natural frequency drift induced by internal flow and cross flow in a straight tube heat exchanger

Using a two-dimensional flow model around a circular cylinder, the lift and drag functions of a straight tube heat exchanger were developed to estimate the external flow action with a wide range of Reynolds numbers. Subsequently, an improved model coupling the internal flow with the external flow was proposed, in which the lift and drag functions were treated as excitations and the added mass resulting from the unsteady internal and external flows was also considered. The results showed that the added mass due to the cross flow led to a drift in the natural frequency of the tube and that the Reynolds number also affected the frequency of the external excitation. Given that the internal flow Reynolds number also affects the natural frequency of the tube, resonance can occur under the combined action of specific internal flow and cross flow. The current model can predict the range of internal and external Reynolds numbers and therefore provide a theoretical basis for reasonably setting the safe operation conditions of internal and external flows.