Random excitation forces in heat exchanger tube bundles

Random excitation forces can cause low-amplitude tube motion that will resu lt in long-term fretting-wear or fatigue. To prevent these tube failures in heat exchangers, designers and troubleshooters must have guidelines that i ncorporate random or turbulent fluid forces. Experiments designed to measur e fluid forces were conducted at the Chalk River Laboratories and at other laboratories worldwide. The data from these experiments were studied and co llated, to determine suitable guidelines for random excitation forces. In t his paper, a guideline for random excitation forces in single-phase cross f low is presented in the form of normalized spectra that are applicable to a wide range of flow conditions and tube frequencies. In particular, the exp erimental results used in this study were conducted over the full range of flow conditions found in the liquid region of a nuclear steam generator. Th e proposed guidelines are applicable to steam generators, condensers, rehea ters and other shell-and-tube heat exchangers. They may be used for flow-in duced vibration analysis of new or existing components, as input to vibrati on analysis computer codes and as specifications in procurement documents. [S0094-9930(00)00603-X].