Numerical Analysis of Flow Field Distribution and Flow Resistance of Open-Cell Foam Structures

Abstract

Purposes This research is carried out in order to systematically study the flow characteristics, heat and mass transfer characteristics of air flow field of open-cell metal foam. Methods The dodecahedron as a single cell of metal foam model is constructed by geometric representation. The influences of parameters of the cross-section shape of foam ligament, pore density (PPI), and the symmetry of foam structure in the direction of flow field at altitude on flow field distribution, mass transfer, and flow resistance at different inlet velocities are simulated by finite element method. Findings The results show that with the decrease of the vertex curvature of the foam ligament cross-section, the blocking of ligaments is weakened, and the friction loss (hf) of flow field decreases. Increasing the pore density can improve the distribution uniformity of convective intensity in flow field. In the height direction, the convection intensity of the asymmetric boundary field is greater, and the distribution of the convection intensity around ligaments tends to be uniform, while that of the symmetric structure is opposite. The convection velocities at the upper and lower boundaries of the symmetric boundary are slightly larger than those at the asymmetric boundary structure, and the symmetric structure is more conducive to mass transport at boundaries. The characteristics of open-cell metal foam structure and gas inlet velocity have obvious influences on the flow field distribution and flow resistance. The dimensional analysis results of the flow problem show that the more the number of pores, the greater the ratio of friction loss of flow field to the initial kinetic energy of the gas, and the ratio is reduced as the inlet velocity increasing. When the inlet velocity is greater than 6 m/s, the ratio tends to be stable.

Keywords

• open-cell metal foam
• ligament cross-section
• symmetry of foam structure
• pore size density
• friction loss
• mass transfer