Effect of Entrance and Exit Areas on the Pressure Drop and Velocity Distribution in Regenerator Matrix

In order to examine the effect of entrance and exit areas on the velocity distribution in stacked wire screens, which are the most familiar regenerator matrices of Stirling cycle machines, the pressure drop across them and the velocity distribution at their exit are measured for different mesh numbers, flow rates, entrance areas, exit areas and stack thicknesses. The results show that the effective flow area ratio, which is an index for the uniformity of the velocity, is independent of the mesh number and the Reynolds number but dependent on the entrance and exit areas and the stack thickness. In addition, a simple theoretical flow model has been formulated based on the isotropy of the friction factor, which is confirmed by the measurement of axial and radial friction factors. The calculation using this model gives an effective flow area ratio and a velocity distribution that agree well with experimental ones.