Computer-Aided Tube Fretting-Wear Predictions

Abstract

Tube fretting in heat exchangers is the result of flow induced tube vibration and fretting-wear predictions are required to determine their long term reliability. The first step is to predict the impact forces between tube supports and vibrating multi-span tubes. A computer model, called VIBIC, has been developed to do this. The next step is to establish experimental force-wear relationships for different tube/support material combinations. This includes the development of a technique to statistically analyse the support impact forces, to a c count for the different types of tube motion.

The VIBIC code can now be used to simulate a vibrating tube to obtain the statistical force functions. These are then used to predict the wear rate from experimentally derived wear-force curves. Examples are used to illustrate the wear prediction technique and other applications are suggested.