Flow Field Simulation of Stator Cascade in Automotive Torque Converters based on Lattice Boltzmann Method

Abstract:

Theory and application of the lattice Boltzmann method (LBM) for flow field simulation in the torque converter stator cascade is studied. Firstly, treatment for rotational periodic boundary is proposed. Then, influence of different parameters on computational stability and efficiency is analyzed. In order to ensure stable calculation of migration and collision process of particles, it is essential to choose appropriate value of the relaxation time, τ to avoid occurrence of negative value of the equilibrium distribution function, feq. Furthermore, the large eddy simulation (LES) is adopted in the LBM to lessen the restriction of computational stability on the relaxation time, τ and to improve computational efficiency. Finally, flow field simulation of the stator cascade is realized by extending function of an open source code named ‘Palabos’, and instantaneous structure of unsteady wake flow behind the stator blade is obtained. The computational result shows that calculated force applied by fluid on the stator blade is nearly the same for the LBM to that of the tradition computational fluid dynamics (CFD) method. However, the LBM has advantage in calculating the forming history of flow filed and complex details of instantaneous flow structure.