Vortex induced vibration (VIV) is a phenomenon experienced by solid bodies placed directly in the path of a flowing fluid. This is a common cause of damage and subsequent failure in sample probes and thermowells alike. This phenomenon is the critical focus of ASME PTC 19.3 TW-2016, which determines fitness for service of specific thermowell geometries in specific process conditions in a pipeline, and is recognized as the mandatory design criteria by most downstream facilities. It is widely understood that the presence of the helical strakes minimizes the formation of coherent vortices. The patented helical strake probe design, employed in VE Technology® is tailored to minimize the effect of VIV.
The study of VIV and minimizing the effects has been an area of extensive research over recent years. This review meeting will present the theory associated with VIV and VIV prevention and then summarize the key findings from experiments undertaken by the University of Bath (2006), Manchester University (2009) and Southwest Research Institute (2017). The University of Bath concluded that a vortex is almost completely mitigated with a presence of helical strakes. The results from Manchester University supported a reduced oscillatory force experienced by a helical strake probe design when compared with a conventional cylindrical probe. Southwest Research Institute flow lab testing provided empirical findings in a controlled, real world application, and involved collaboration with several of the nation’s leading owner/operators.