Showing papers on "Slug flow published in 1971"

Pressure drop and holdup in horizontal slug flow

Abstract: The Dukler-Hubbard slug-flow model is used along with independent correlations for in situ holdup and slug frequency to predict pressure drops for two-phase slug flow. The holdup and frequency correlations are for the most part based on data for air-water flowing in a 1.50-in. pipe. Predictions of pressure drop using this approach are compared with experimental data taken from studies utilizing various systems and pipes from 1.50 to 6.065 in. in diameter. Alternative correlations by Dukler and Hughmark for predicting two-phase pressure drops and holdup, respectively, are included for comparison. In general, the present approach is at least equivalent to the Dukler-Hughmark method, and for values of ΔP/L > 0.06 lb./sq. in./ft. appears to be slightly better.

Upward Liquid Flow in Small Tube into which Air Streams : 1st Report, Experimental Apparatus and Flow Patterns

Abstract: In the main fuel pipe (main nozzle) of the carburetor of gasoline engine, a little air is let into the fuel stream, in general. This two-phase flow streams into the venturi-tube. The author's experiments are made with simple models to elucidate the basic phenomena of the confluence of air and fuel in a small tube, that is, the flow pattern of a two-phase flow, the pressure drop caused by the confluence, the two-phase flow friction, and the relaxation oscillation. In 1st Report, experimental apparatus and flow pattern are described. Vertical tubes are 6, 3, 2 mm of diameter. Liquid is tap water in the most part of experiments, and in some part of them, is distilled water, gasoline, solvent, or surface active agents solution, Unless the air holes are large, stable fish-scale type slug flow appears in some range of air and liquid. This is attributed not to the effect of so-called entrance length but to that of the small diameter of tube.

Two‐phase slug flow in horizontal and inclined tubes

Abstract: Slug flow in the air-water system near atmospheric pressure was studied in a one-half inch diameter tube. Measurements of flow characteristics, pressure gradient, pressure fluctuations, slug velocity and frequency were made for horizontal and inclined flow. A semi-empirical theory based on a simple model was developed. Pressure losses calculated from this theory require a priori knowledge of the slugging frequency. A comparison of the prediction of the theory and two published correlations shows that the proposed theory gives better agreement with the data.

Studies on the Fluctuation of pressure Drop in Two-Phase Slug Flow : 1 st Report, Experimental Study

Abstract: Experimental and theoretical studies of the fluctuation of air-water two-phase slug flow in a vertical tube, have been described in three papers. Among them, the experimental results are presented in this paper. It was verified that the time variation of pressure drop is predicted by the variation of lengths of gas bubble and liquid slug flowing in the tube. It was also shown that the probability distribution of pressure drop in long segments of tube is normal distribution, and that in short segments, distribution has generally two peaks at Δp* (i.e., dimensionless pressure drop) =0 and 1. The maximum amplitude of the pressure drop was given by the following empirical equation δΔpmax*/Δpm*=0.7LT-0.62wl0-0.62wg00.9 where, δΔpmax* and Δpm* are the maximum amplitude and the mean value of dimensionless pressure drop, respectively; wl0 and wg0 superficial liquid and gas velocity, respectively; and LT is the length of segment of tube.

Propagation of Pressure Wave in Air-Water Two-Phase System, (II)

Abstract: In an attempt to gain information on the propagation characteristics of pressure waves in a two-phase system consisting of gas and liquid, experiments were performed on a nonflowing air-water mixture in a range of pressures from 1.0 to 7.5 bar and void fractions from 0 to 60%. Stepwise pressure disturbancies were applied to a water column dispersed with rising air bubbles by bursting diaphragm. The pressure transients at several points down the fluid column were measured with strain gage type pressure transducers and recorded on magnetic tapes. The nonlinearity of the pressure wave records was scarcely marked. The propagation velocity of pressure wave front down the fluid column was found almost independent of the magnitude of the pressure change applied, nor whether it was depressive or compressive. At higher void fractions where the flow regime became sluggy, the measured propagation velocities showed increasing deviation from the calculated values based on the nonslip homogeneous adiabatic model, thoug...

554. ナトリウム-アルゴン垂直上昇2相流のボイド率と熱伝達率

Abstract: The void fraction in a vertical upward two-phase flow of Na-Ar was measured using electro-magnetic flow meters and γ-ray attenuation. It was found that with a flow pattern of bubbly flow, the statistical error induced in measurements of void fraction was slightly greater when using γ-ray attenuation as compared to electro-magnetic flow meters, while with slug flow electro-magnetic flow meters method were quite incorrect.Measurements were also made on the heat transfer coefficient of Na-Ar twophase flow with uniform heat flux. The oddition of a small quqntity of the hiected Ar decreased the heat transfer coeffcient, but upon further increase of the gas content the coefficient increased after passing a minimum value.

Studies on the Fluctuation of Pressure Drop in Two-Phase Slug Flow : 3 rd Report, Pressure Recovery behind a bubble, and Lengths of Bubble and Liquid Slug

Abstract: The variation of pressure difference in a vertical tube when a single gas bubble rose in still water, was investigated experimentally and theoretically, as a fundamental study of two-phase slug flow. The pressure recovery ΔpR due to the momentum of liquid film around a gas bubble was studied experimentally. It was shown that ΔpR is about 30 kg/m2 or less theoretically, and agrees with the experimental value. Moreover the theory was extended to the general two-phase flow, and the results that ΔpR takes a value of 40∼50 kg/m2, was obtained experimentally and theoretically. And also the statistical characteristics of the lengths of bubble and slug were described, which were used in the analysis of the fluctuation of pressure drop in the 1st and 2nd reports.