Numerical simulation of 2-dimensional radial unsaturated flow in liquid composite molding processes

A dual-scale unsaturated flow model was established by introducing the sink function, and the finite element/control volume method was employed to simulate numerically 2-dimensional radial flow in liquid composite molding(LCM) processes under the conditions of constant pressure and constant flow. The pressure distribution and time-varying resin flow front were obtained and compared with the results of theoretical prediction of single-scale model. The simulation results show that during unsaturated flow process, pressure and pressure gradient drop significantly in the unsaturated region; the length of unsaturated region increases firstly and thenkeeps constant, when the saturated flow front reaches the exit, the length begins to decrease; when there is a difference in permeability of two principal direction, the length of unsaturation region in the direction of higher permeability is longer and the time to completely infiltrate the fabric depends on the smaller permeability. The research results have significance to reasonably predict the pressure distribution and the infiltration of the fiber preform in the resin filling process.