Fluidelastic Instability in a Tube Array Subjected to Two-Phase R-11 Cross-Flow

Abstract This paper reports on an experimental investigation of flow-induced vibration in a parallel triangular tube bundle with a pitch to diameter ratio P/D = 1·44. The cantilevered tube bundle was subjected to cross-flow of both single phase and two-phase refrigerant R-11 and the results obtained were analysed to determine the critical flow velocity for fluidelastic instability as well as to observe the nature of the two-phase flow. The data of other researchers were compared with the results of the present study by means of dimensionless similitude parameters. The primary contribution of the study is the comparison of the use of single component two phase mixtures such as R-11 liquid and vapour with two component mixtures such as air-water on the response of dynamically scaled model tube arrays. Some of the results suggest a lower stability threshold associated with the R-11 two-phase mixtures than similar experiments conducted with air-water two-phase mixtures. It appears that commonly ignored factors such as slip between phases and flow regime may have a significant effect on stability behaviour.