Modeling of a stacked-screen regenerator in an oscillatory flow

In this paper, we model tortuous flow channels of a stacked-screen regenerator as a bundle of cylindrical tubes to analyze and design thermoacoustic Stirling engines. The oscillatory flow resistance of stacked-screen regenerators is measured and compared with those obtained using empirical equations to verify the applicability of those empirical equations to oscillating flows of pressurized Ar and He gases. It is then converted to an effective radius parameterized by Reh and r₀/δ_ν, where Re_h represents the Reynolds number based on velocity oscillation amplitude, r₀ is Ueda's effective radius (= √ d_hD/2, where d_h is the hydraulic diameter and D is the mesh wire diameter), and δ_ν denotes the viscous penetration depth. The applicability of the proposed effective radius is demonstrated experimentally when the axial temperature gradient is imposed on the regenerator.