Numerical study on fluid excitation to thermowells

Thermowells are process-critical devices that protect thermometers which are used to measure the fluid temperature in a pipe from harsh industrial fluids. In practical applications, thermowells are often fractured due to the impact of the fluid flow with high velocity and high temperature. It has been proved both theoretically and practically that the main reasons of thermowells damage lie in heavy loads and periodic forces caused by vortex flow, which could excite the vibration of the thermowell, leading to resonance and damage. An improved scheme is put forward in this paper to reduce the fluid load acting on the thermowell and suppress the structural resonance by setting up an interference device in front of the thermowell. The unsteady internal pipe flow-fields around the specified thermowells are simulated, respectively, with and without an interference device by using LES technique. The force and the vibration of the thermowells induced by the unsteady flow are analyzed. The effectiveness of the interference device in protecting thermowells is verified by comparisons of the simulated results under the above two conditions. It shows that the interference device can effectively suppress the vibration and reduce the resultant force of the thermowell.