Countercurrent flow limitation in narrow rectangular ducts

Countercurrent air-water two phase flow limitation in vertical narrow rectangular ducts was investigated. The scale effect was investigated using three narrow rectangular ducts with different gaps (2 x 100, 5 x 100, 10 x 100 mm). The experimental data showed similar tendency in spite of gap or upper plenum liquid level. The Wallis type correlation with constant C = 0.65 gave a good agreement with the experimental data. A comparison with the prediction by the envelope theory using the Bharathan friction factor correlation was also discussed. (author)