MICRO-SCALE CFD MODELING OF OSCILLATING FLOW IN A REGENERATOR
- University of Wisconsin Madison, WI, 53706 (United States)
Regenerator models used by designers are macro-scale models that do not explicitly consider interactions between the fluid and the solid matrix. Rather, the heat transfer coefficient and pressure drop are calculated using correlations for Nusselt number and friction factor. These correlations are typically based on steady flow data. The error associated with using steady flow correlations to characterize the oscillatory flow that is actually present in the regenerator is not well understood. Oscillating flow correlations based on experimental data do exist in the literature; however, these results are often conflicting. This paper uses a micro-scale computational fluid dynamic (CFD) model of a unit-cell of a regenerator matrix to determine the conditions for which oscillating flow affects friction factor. These conditions are compared to those found in typical pulse tube regenerators to determine whether oscillatory flow is of practical importance. CFD results clearly show a transition Valensi number beyond which oscillating flow significantly increases the friction factor. This transition Valensi number increases with Reynolds number. Most practical pulse tube regenerators will operate below this Valensi transition number and therefore this study suggests that the effect of flow oscillation on pressure drop can be neglected in macro-scale regenerator models.
- OSTI ID:
- 21371794
- Journal Information:
- AIP Conference Proceedings, Vol. 1218, Issue 1; Conference: International cryogenic materials conference (ICMC) on advances in cryogenic engineering materials, Tucson, AZ (United States), 28 Jun - 2 Jul 2009; Other Information: DOI: 10.1063/1.3422339; (c) 2010 American Institute of Physics; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
COMPUTERIZED SIMULATION
CORRELATIONS
CRYOGENICS
FLUID MECHANICS
FLUIDS
FRICTION
FRICTION FACTOR
HEAT TRANSFER
NUSSELT NUMBER
OSCILLATIONS
PRESSURE DROP
REYNOLDS NUMBER
SCALE MODELS
SOLIDS
STEADY FLOW
DIMENSIONLESS NUMBERS
ENERGY TRANSFER
FLUID FLOW
MECHANICS
SIMULATION
STRUCTURAL MODELS