A new tube/support impact model for heat exchanger tubes

Heat exchanger tubes are often loosely supported at intermediate points by plates or flat bars. Flow-induced vibrations result in fretting wear tube damage due to impacting and rubbing of tubes against their supports. Prediction of tube response relies on modelling the nonlinear tube/support interaction. The evaluated response is used to predict the resultant wear damage using experimentally measured wear coefficients. An accurate prediction of impact forces and work rate is therefore paramount. The analytical models available in the open literature generally assume tube/support contact occurs at a single point. In this paper, a computational algorithm is proposed to describe tube/support impact considering a finite support width. The new model provides a means of representing tube/support contact as a combination of edge and segmental contact. The proposed model utilizes a distributed contact stiffness to describe the segmental contact. The formulation also incorporates a stick/slip friction model. The model developed is utilized to simulate the dynamics of loosely supported tubes.