CFD Modeling of Flow Induced Vibration on a Mobile Cylinder for a 30 K-60 K Reynolds Number Comparison Between Simulation and Experimental Results

Fatigue and aging of electrical overhead transmission lines is a major concern nowadays in developed countries with ever increasing difficulties to build new lines and an already quite aged network. An important degradation phenomenon of overhead line cables is fretting fatigue close to the suspension clamps due to vortex induced vibrations (VIV). These VIV are generally observed for wind speeds in the range of 1 to 7 m/s. The existing industrial practice for predicting how prone cables are to VIV fatigue is based on a balance between the power generated by the wind and the power dissipated by the cable system. The power generated by the wind has been evaluated through measurements on real line spans and through wind tunnel experiments on rigid and flexible cylinders as a function of frequency and vibration amplitude. The wind tunnel measurement results are mainly performed for constant flow speed. Corresponding results show a scattering from simple to double. Furthermore, complementary investigations are required to better evaluate the power with wind speed variations across and along the overhead line span. EDF R&D (with Code_Saturne open source software) and Politecnico di Milano have evaluated CFD modeling on a mobile rigid cylinder with comparison to detailed wind tunnel measurement results performed by Politecnico di Milano on a 20 cm diameter rigid cylinder equipped with a pressure scanner. This paper presents the steps, the different questions raised, the difficulties and limitations for the setting and the realization of the CFD modeling approach. The comparison between experimental results and simulation results is presented for the mobile rigid cylinder with k-ω SST turbulence model.