An experimental study on flow resistance of regenerator wire meshes in oscillatory flow [in Stirling engines]

This paper describes the experimental results on fluid motion in regenerator wire meshes of a Stirling engine in a oscillatory flow. Theoretical analysis on laminar flow in a circular pipe is described for comparison. Simultaneous measurements of velocity nearby the mesh layer in the test section, pressure drops between the entry and exit points of the mesh layer and a photo signal of the top position of the piston were carried out under oscillatory flow conditions. Experimental result shows that variation of pressure drops slightly advances toward velocity variation as is clarified in the theoretical analysis on laminar oscillatory flow in a circular pipe. Friction factors, defined by adjusting the phase angle shift between pressure drops and velocity variations, show that it appears larger in the accelerating period than in the decelerating period. This phenomenon seems to be explained because fluid motion requires more energy to make an eddy structure in the accelerating period, while fluid motion in the decelerating period requires less energy as a streamwise eddy structure is already developed.