Abstract
In Stirling engines and cryocoolers, the regenerator is the indispensable heat exchanger. The regenerator exists between the heater and the cooler in engines, and between the expansion space and the compression space in cryocoolers. So, the flow passage at the regenerator ends is reduced in size. The effects of the small passage on the velocity distribution of working gas in the matrix cause increased flow loss and decreased thermal performance. In this paper, the effects of gap distance between regenerator ends and matrix on flow area in matrix, are examined by unidirectional steady flow apparatus.