Assignment:
1. Consider a vertical-upward air-water two-phase flow in a round pipe with 2.54 cm inner diameter. Assume that the flow is operating at 25 °C under atmospheric pressure condition. Use any graphing software and generate the two-phase flow regime map proposed by Mishima and Ishii (1984). Submit both the flow regime map showing four regime transition boundaries and a screen shot of the spreadsheet as part of the solution.
2. Prediction for flooding phenomenon can be made for various combinations of liquid and gas flow rates by identifying tangential lines at the flooding points in the graph of jgf vs. α . Given that jgf is correlated with α by:
jgf = α (1-α )n vr∞ ,
the "flooding line" can be generated when one plots flooding solutions in jg vs. jf graph for varying void fractions by employing the following relations:
jg = α2 vr∞ n(1-α )n-1 and jf = -(1-αn)vr∞ (1-α ) n
(a) Derive Eq. (1) by using the analogy of identifying tangential lines at the flooding points in the graph of jgf vs. α .
(b) For a bubbly flow of a certain mixture, it is given, that n=1.1 and the terminal velocity vr∞ is 30.0 cm/s. Using any graphing software, plot jg vs. jf (in y and x axes, respectively) for varying void fractions to obtain flooding lines.