Countercurrent flow limitation in a pressurizer surge line

Effects of Diameters on Countercurrent Flow Limitation at a Square Top End in Vertical Pipes

“…In region "R-III", all data were obtained with the protruding top end. K and m in region "R-IV" with the small diameters of D = 19-25 mm and the water level at midlevel were outside the range of values calculated by using (8). Our major interest is CCFL in large diameters with the square top end, and therefore all data in Regions "R-I" and "R-II" and data with large diameters in region "R-III" are plotted in Figure 8(b).…”

“…Computations with the Annular Flow Model. CCFL characteristics in vertical pipes can be computed by using the annular flow model with the maximum flow condition of ( * L / ) = 0 or ( * G / ) = 0 and correlations for the interfacial friction factor and the wall friction factor (Richter [9]; Bharathan and Wallis [20]; Sudo [21]; Yamamoto et al [8]). In the computations, the correlation for the interfacial friction factor is important.…”

“…As shown in Figure 7(a), however, the K value by Richter [9] had a maximum at an intermediate diameter and decreased with increasing the diameter toward large diameters due to the protruding end. The correlation for the interfacial friction factor improved by Sudo [21] gave a small K value for a large diameter (Yamamoto et al [8]). Therefore, the correlation for the interfacial friction factor should be improved to apply it to a large diameter without a protruding end.…”

“…CCFL data reported by Richter [9] and Doi et al [10] are well expressed by the Kutateladze parameters. From the data of D =19-140 mm in Figure 1(a), the Wallis-type correlation (6) was derived using the least-square method (Yamamoto et al [8]). * 1/2 G…”

“…In available data (Takeuchi et al [5]; Futatsugi et al [4]; Yu et al [6,7]), the pipe diameters were D = 30-90 mm, so that the CCFL data were not sufficient to evaluate effects of the diameters. In the pressurizer surge line, the falling liquid flow rate is limited at the square top end of the vertical pipe, and so we (Yamamoto et al [8]) derived a correlation for CCFL-U at the square top end for the pressurizer surge line by using existing data for D = 19-140 mm (Richter [9]; Doi et al [10]). However, CCFL-U behavior is very complex and there are some disagreements among experimental data.…”