Void distribution in a shallow bubbling pool
An analytical model based on the variational principle of minimum energy is derived to determine the steady-state two-phase mixture level and axial void distribution of a non-condensable gas that is introduced uniformly across the base of a shallow liquid pool. The model expresses pool void fraction and mixture level in terms of the Froude and Weber numbers, while the void fraction just below the free surface depends only on the Weber number. The shallow pool model is based on the assumption of one-dimensional flow of an inviscid bubbly mixture in a pool with its height much less than its diameter. It is also assumed that both the hydrostatic pressure of the pool and the pressure difference across the bubble surface are much smaller than the ambient pressure. By including the dependency of the added mass coefficient on void fraction, the model predicts a maximum bubbly flow void fraction of 0.3 which agrees well with the observed transition from bubbly to churn-turbulent flow at a void fraction between 0.2 and 0.3. When the theoretical results for an inviscid shallow pool are compared with available experimental data for void fraction in pools which are not shallow and hence the viscous and wall effects are not negligible, the model under-estimates the data on pool fraction by about a factor of 5. Good agreement is obtained between the inviscid model and a drift flux correlation for pool void fraction when the viscosity of water is extrapolated to 1/10 of the value at room temperature. 14 refs., 7 figs.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5968477
- Report Number(s):
- BNL-42658; CONF-890819-19; ON: DE89014517
- Resource Relation:
- Conference: ASME/AIChE national heat transfer conference, Philadelphia, PA, USA, 6-9 Aug 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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