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This paper presents a theory for condensing fluid flow in pipes. The theory incorporates the Reynolds flux concepts, advanced by Silver and Silver and Wallis, to account for the modification of interfacial shear when a phase change occurs across an interface. The basic theory is applicable to any fluid condensing in the annular two-phase flow régime and enables good predictions to be made for the local values of phase velocity, static pressure, and amount condensed. A comparison has been made with published experimental data for steam condensing with velocities in the range 380–730 ft/s, i.e. turbulent vapour core and a laminar/turbulent condensate film. A further outcome of the comparison with experimental data is a rationalization of the Reynolds flux concept with less empirical modification.

The theory of evaporating flow given in this paper is believed to be an advance on what has hitherto been available in that it makes due allowance for the effect of vapour condensation which occurs simultaneously with vapour expansion. The basic theory is applicable without modification to any fluid undergoing evaporating flow in the annular mode, given suitable correlations for wall and interphase friction factors as defined in the paper. Preliminary correlations, which can only be very rough, are provided for water. A lot of experimental work on a variety of fluids would be required to achieve a position from which general correlations could be developed. The theory incidentally permits prediction of critical outlet conditions and some interesting comparisons with available experimental data have been made.

Abstract The new analysis technique of Annular Flow Dynamics is a simple, practical way to predict and control rheology and hydraulics in predict and control rheology and hydraulics in Drilling Fluid Systems. It is based on field experience in the sloughing shale areas of Canada and on a recently developed method of calculating Annular Pressure Losses with greater accuracy and more simplicity than previous methods. previous methods. Annular Flow Dynamics is primarily oriented towards improving drilling practices in sloughing shale situations. However, as holes become deeper, additional restrictions are imposed on casing programs and hole size. These make it even more important to be able to determine and possibly predict certain drilling fluid parameters for maximum performance. This paper shows how, by use of performance. This paper shows how, by use of a logarithmic plot of viscometer data, the following can be determined:Effective annular viscosities at any pump rate and for any flow properties.Flow type (laminar or turbulent).Accurate annular pressure losses.Approximate bit nozzle shear rates.Upper and lower limits on both flow properties and pump rates for optimum well bore stabilization and minimum E. C. D. (Equivalent Circulation Density).Approximate ascending velocity of cuttings. In the past year, Annular Flow Dynamics has been used on a field basis in Canada with very positive results. Introduction Well bore instability occurs primarily when shales absorb water. Controlled activity oil minds are presently the only way to satisfy the shales affinity for water. The mechanism of sloughing shales due to actual change in the physical and chemical properties of the shale physical and chemical properties of the shale have been thoroughly researched and discussed by the industry. Less attention has been paid to the mechanical aspect of stabilizing shales by well planned and flexible rheological and hydraulics programs.

In the low pressure parts of steam turbine, the annular flow areas are made diverging towards the downstream. In such a case, the fluid behaves the radial velocity which cannot be neglected in the calculation, In the beginning of this paper, a method to calculate the velocity distribution through such stages is presented, and some examples of application for the concrete flow pattern are described. And next, some results of the measurement of the flow through the last stage of actual marine turbine are described, showing that there exists good agreement with theoretical prediction.