Two‐phase critical flow of steam‐water mixtures

Abstract

Critical flow of two-phase steam-water mixtures in annuli has been studied, with a cylindrical test section 0.574 in. in diameter with an axially centered rod, 0.187 or 0.375 in. O.D., as a pressure probe. Pressure taps on the wall and the center rod permitted an accurate determination of the pressure profile over the entire length of the section, and, in cases where a movable probe was used, a short distance into the downstream exhaust chamber. Results were correlated by plotting the ratio of the observed critical mass velocity to the theoretical critical mass velocity for homogeneous flow as a function of quality.Exit pressures were found to be lower than most values previously reported. The ratio GJGTH was found to be independent of the probe diameter, the manner of upstream steam-water mixing, and, for test sections greater than 9 in. in length, the test section length. Since probe diameter had no observable effect on GJGTB, the correlation may be applicable to full bore pipes near % in. in diameter. In the range of qualities from 2 to 15% the critical G,,/GTx ratio was depressed with increasing exit (throat) pressure, but a t other qualities no pressure dependency was noted. The effect of changing the downstream exhaust chamber pressure was found to influence the exit pressure but to have little effect on the observed critical mass velocity.

Choking two-phase flow literature summary and idealized design solutions for hydrogen, nitrogen, oxygen, and refrigerants 12 and 11

“…[ [19] and Miller, Burnell and Linning, the They assumed an annular flow model with no slip velocity, and applied the conservation equations and a form of (5 …”

“…All, or nearly all of the solutions reported in the last few years have been programmed for [19] solution on the computer. Figure 7 from Zaludek shows numerical solutions presented in a very usable chart form.…”

“…Using the void fraction prediction of Martinelli, Firey computed [19] values of (17) is the ratio of the mass ratios of flow of liquid predicted with a discharge coefficient of one to the two-phase mass flow rate. C is the liquid contraction coefficient for the orifice, [49] and also tend to agree with the conclusions of Pasqua .…”

“…[37] Earlier investigators were perhaps less careful with respect to this measurement. Linning for example, measured temperatures which can be translated into pressure measurements only [19,75] if thermal equilibrium is additionally assumed. Some investigations mentioned previously reported choking pressures may be in error because of relatively long extrapolations of the pressure curve from the last measured pressure to the exit of the test section.…”

“…Some investigations mentioned previously reported choking pressures may be in error because of relatively long extrapolations of the pressure curve from the last measured pressure to the exit of the test section. In some [19] examples The separation would be expected as a consequence of the relatively undisturbed flow. This separation would provide a smaller interface area for the heat and mass transfer processes mentioned previously and thus make metastability more likely.…”