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Showing papers on "Slug flow published in 1970"



Journal ArticleDOI
TL;DR: In this paper, the authors extended the Graetz problem in heat transfer to the analysis of mass transfer in circular ducts for the cases where wall resistance is included and where non-Newtonian fluids that obey Casson's equation are considered.
Abstract: The Graetz problem in heat transfer is extended to the analysis of mass transfer in circular ducts for the cases where wall resistance is included and where non-Newtonian fluids that obey Casson's equation are considered. The eigenvalues and fluid bulk coefficients are presented for the fluid between the extremes of Newtonian and slug flow. It is found that for fluids which are only slightly non-Newtonian, such as blood, which is closely approximated by Casson's equation, the mass transfer rate can be predicted by Newtonian fluid analysis without appreciable error. Some experimental results give support to the theory.

49 citations


Journal ArticleDOI
TL;DR: In this article, the steady-state mass transfer with axial diffusion of decaying products resulting from the disintegration of an inert gas is considered for a slug and a Poiseuille pipe flow, where the products of disintegration are filtered out at the tube inlet but are again generated by radioactive decay of a flowing inert gas along the cylindrical tube.

36 citations


Journal ArticleDOI
TL;DR: In this paper, a laminar boundary-layer model is proposed to account for viscous losses during the transient turbulent flow of a liquid in a tube, where inviscid slug flow is assumed for the core and all viscous effects are assumed to occur in the boundary layer.
Abstract: A laminar boundary-layer model is proposed to account for viscous losses during the transient turbulent flow of a liquid in a tube. In this model, inviscid slug flow is assumed for the core and all viscous effects are assumed to occur in the boundary layer. The transient boundary-layer velocity distribution is determined as a function of a prescribed variation in core velocity and the associated pressure gradient. Both analytical and numerical solutions are presented. This transient flow information is used to calculate local and integrated energy dissipation rates which are then combined, with one-dimensional energy analyses. The result is a prediction of the decrease in pressure-wave magnitude due to viscous dissipation, and a comparison is made with experimental data for rapid flow extinction. Good agreement between the observed and predicted results is obtained.

29 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used two quick closing valves to trap a portion of the flow stream and then measured the trapped liquid using the velocity of the gas bubble and the velocity in the annular region.
Abstract: H. D. Beggs. This paper is a welcome addition to the limited work in the area of two phase flow in inclined pipes. Some question arises, however, as to the adquaey of the experimental apparatus used in the study. Griffith and Wallis [1] have shown that entrance effects can persist for lengths as much as 300 pipe diameters in two phase flow. Since the pipe length used by Singh and Griffith was only 20 ft, most of their data were taken in a region where the flow could still be developing. McDonald and Baker [2] indicate that the developing region may be as much as 500 pipe diameters in inclined pipes. The void fractions were determined using two quick closing valves to trap a portion of the flow stream. A description of the method used to measure the trapped liquid would be of interest. Assumptions 3 and 4 imply that there is no pressure drop in the gas filled portion of the pipe. These assumptions are valid if the bubble length is small, but for long bubbles they oversimplify the problem. If the flow pattern developed into the annular region, there would be no pressure drop at all under these assumptions. I t is also assumed that the acceleration pressure drop is negligible. This is a reasonable assumption for low velocities, but Hoogendorn [3] showed that the acceleration pressure drop could be as much as 15 percent of the total pressure drop under certain conditions. Street [4], in a study of vertical slug flow, concluded that the effects of liquid acceleration around the gas bubble cannot be ignored. The authors state that in some cases negative friction pressure drops were obtained. Was this concluded in cases where the calculated gravity pressure drop exceeded the observed total pressure drop? Hagedorn [5] also observed this for the vertical case, but after correcting his values for void fraction and consequently calculated gravity pressure drop, the negative friction condition was eliminated. In equation (4) for bubble velocity, the second term

28 citations


Journal ArticleDOI
TL;DR: In this paper, the growth of the thermal boundary layer and the heat transfer problem in a steady, axially symmetrical slug flow of an incompressible, isotropic medium with constant physical properties, without internal heat sources assuming mixed boundary conditions, were studied.

12 citations



Journal ArticleDOI
TL;DR: In this article, the effect of a single air chamber on the propagation of a pressure surge in a line is carried out, where the pressure surge is generated by rapid closure of a downstream valve.
Abstract: An investigation of the effect of a single air chamber on the propagation of a pressure surge in a line is carried out. The pressure surge is generated by rapid closure of a downstream valve. Both a distributed parameter wave analysis and a lumped parameter slug flow analysis are formulated to describe the transient flow situation. It is shown that short term effects, which are not predicted by a lumped parameter analysis, may be important, and that the magnitude of the short term surge may be many times greater than that predicted by a lumped parameter analysis. It is further shown that an optimum design of an air chamber is possible, and this is dependent on short term effects. Experiments are conducted which are in close agreement with predicted results. It is pointed out that the performance of an air chamber must be evaluated relative to a specific application and that an accurate transient analysis is necessary and can be accomplished utilizing the approach described herein.

7 citations


Journal ArticleDOI
TL;DR: In this article, a theoretical study of heat transfer for in-line slug flow through unbaffled equilateral triangular bundles is reported, and results are given for the pitch: diameter range 1.05 to 2.00
Abstract: A theoretical study of fully developed heat transfer for in-line slug flow through unbaffled equilateral triangular bundles is reported. Results are given for the pitch: diameter range 1.05 to 2.00...

5 citations


Journal ArticleDOI
TL;DR: In this paper, the authors considered the problem of simultaneous development of velocity and temperature profiles in the case of a laminar flow in the entrance region between two flat plates, and showed the influence of parameters such as the optical thickness, the ratio of conductive energy to radiative energy and Graetz number on the temperature variation across the duct and the heat transfer rates.
Abstract: Consideration is given to heat transfer for the problem of simultaneous development of velocity and temperature profiles in the case of a laminar flow in the entrance region between two flat plates. The duct consists of two diffuse, black, isothermal parallel surfaces separated by a finite distance. A medium filling the space between plates emits and absorbs thermal radiation. Numerical solutions are obtained for a slug flow (Pr=0), a flow of the inlet region (Pr=1) and a fully developed flow that was shown in the 2nd report, and show the influence of parameters such as the optical thickness, the ratio of conductive energy to radiative energy and Graetz number on the temperature variation across the duct and the heat transfer rates. The radiative heat transfer rate is scarcely affected but the convective one is much affected by flow patterns. An approximate method for the prediction of heat transfer rates in any flow patterns is shown and the results are in good agreement with the exact ones in the region of large optical thickness.

3 citations



Journal ArticleDOI
30 Jun 1970
TL;DR: In this paper, the authors measured the steam volume fraction of a two phase mixture in the low quality and low mass velocity region, as the fluid flowed upward under atmospheric pressure in 4-rod and 7-rod bundle geometries of triangular lattice (9.5mm O.D. and 1m long, 1.37 and 1.79p/d ratio).
Abstract: The steam volume fraction of a two phase mixture was measured in the low quality and low mass velocity region, as the fluid flowed upward under atmospheric pressure in 4-rod and 7-rod bundle geometries of triangular lattice (9.5mm O.D. and 1m long, 1.37 and 1.79p/d ratio).The experiments were performed with use made of a capacitance-type void meter described in previous papers, and by supplying various heat inputs into each rod heater.The results indicate that:(1) In the bubble flow region, a significant peaking in void fraction was observed in the transition to slug flow in all the experimental runs. This is probably related to the effects of turbulent interchonge and diversion cross-flow between adiacent subchannels, under conditions of two phase flow.(2) In the slug flow and annular flow regions with large disturbance waves, 4-rod bundle data were 5% lower than those in circular tube and concentric annulus, and 7-rod bundle data 10% lower. These results can be explained by Griffith's(3) correlation with bubble rising velocity, in which channel geometries are considered. Taking account of channel geometry, the authors' correlation proposed in the previous paper is also valid in predicting the void fraction in rod bundle geometries.