This paper describes an experimental investigation on helium-air exchange flow through multiple openings, i.e., a opening with a partition. A vertical partition is in alignment with center line of the opening to make the multiple openings.
The exchange flow through the multiple openings was experimentally investigated. Dimensionless exchange flow rate (Froude number) was evaluated as a function of opening ratio H1/Df, where H1 and Df are height and effective diameter of the opening, respectively. At lower opening ratios (H1/Df < 0.75), the exchange flow rates through the multiple openings were almost the same as those through a single opening. However, at higher opening ratios (H1/Df ≥ 0.75), they were larger than those through a single opening because upward and downward flows were separated by the vertical partition. In this study, effect of inner diameters of the openings on the exchange flow rate was experimentally investigated at higher opening ratios. The inner diameters of the openings D1 are 10, 20, and 40 mm, and the opening ratios are in the range 0.6 to 10. The measured Froude numbers increased with the opening ratios and the inner diameters.
The exchange flow rate was evaluated by balance between pressure loss and difference of static head. The pressure loss due to fluids interaction out of entrance and exit was modeled as the loss of the laminar plane wall jet. The interaction between the upward and downward flows out of the entrance and the exit of the opening with the partition was found to be an important factor on the exchange flow rate. The present modeling is useful to predict relationships of the measured Froude numbers on the opening ratios and the inner diameters.