In industrial pipe circuit, local flow instabilities generate planar pressure waves propagating upstream and downstream from the source location. In case of resonance, this can lead to important pressure fluctuation in the entire circuit. The aim of this study is to develop a concurrent simulation strategy in order to model this phenomenon.
Doctoral student : Nicolas Ruchonnet
The methodology is the following, the source term of the Lighthill equation is calculated with a 3D CFD model of the local flow instability and a 1D pipe flow model is used to compute the response of the circuit. As the Eigen frequencies of the circuit are strongly influenced by the pipe wall deformation, the 1D model includes simplified fluid-structure interaction terms. The feed-back effect of the circuit on the flow instability must also be taken into account. For this reason, the boundary conditions of the CFD model are adjusted at each time step using the data from the pipe flow model. The method is validated with experimental data. The test case is a PVC pipe placed between two large constant pressure reservoirs. The resonance is induced by the shedding of vortices in the wake of a bluff body placed cross flow at ¾ of the pipe length.