Martha Salcudean

Effect of flow-obstruction geometry on pressure drops in horizontal air-water flow

Abstract Experiments were carried out to investigate the pressure drop due to flow obstructions in horizontal air-water flow. The axial pressure distribution along a 25.4 mm inside diameter tube, with and without flow obstructions was measured using multi-tube manometers. Various obstruction shapes and sizes were investigated. Pressure-loss coefficients and two-phase multipliers were derived for twelve different flow obstructions. Estimates of the kinetic energy and momentum of the flow were also obtained from radial void distribution measurements. The pressure drop through the obstructions in two-phase flow was found to depend strongly on the kinetic energy and momentum of the liquid intercepted by the flow obstruction. Buoyancy-induced flow stratification caused a strongly non-symmetrical effect, and resulted in large pressure drops for flow obstructions located in the bottom part of the channel.

COMPUTATION OF THREE-DIMENSIONAL FLOW AND HEAT TRANSFER IN GAS AGITATED REACTORS

Abstract Equations have been written, and a computational scheme developed, for predicting flow fields and heat transfer phenomena associated with asymmetric gas-driven flows in systems of cylindrical geometry. Cases considered include axisymmetric gas injection wherein the gas-liquid plume is either of constant radius, or expands in a cone-like manner towards the surface. It is, thereby, shown that the model compares reliably with existing axisymmetric computations. Non-central gas flows are then considered and resulting 3-D liquid flow patterns computed. Finally, the temperature fields in an initially stagnant and thermally stratified liquid resulting from the local introduction of gas on the bottom surface is illustrated

A three dimensional representation of fluid flow induced in ladles or holding vessels by the action of liquid metal jets

A three dimensional flow model is proposed for describing the recirculatory flow patterns generated by coherent jets of metal entering ladles or holding vessels. Based on previous lam-inar and turbulent flow models1,2 developed for axisymmetric conditions, it was decided that a transient three dimensional, laminar flow model was best suited to predict the effect of jet angle, jet location and ladle aspect ratio on resulting flow patterns. It is shown that the ladle’s shape and the jets location and entry angle are critical in establishing the nature of the recirculating flow patterns, and that in some instances, surface flow along the minor axis can reverse.

Turbulent Flow in Filling Ladles

The fluid flow patterns generated during the course of tapping operations from Basic Oxygen Furnaces have been analyzed using two mathematical models of the filling process. The present work is mainly concerned with the application of the κ — ∈ turbulent flow model to describe recirculatory flow in filling ladles. Predicted velocity fields were quite similar to those based on the laminar flow model and both models provided predictions which checked reasonably closely with experimental values using a one tenth scale model. Based on the full scale predictions, it is suggested that the magnitude of flow velocities are technologically significant in terms of their effect on ferro-alloy immersion times.

Fluid flow in filling ladles

The fluid flow generated during the course of tapping operations from Basic Oxygen Furnaces was analyzed. Mathematical models of the filling process were developed, and their predictions checked with experimental values obtained using a one-tenth scale model of the ladle. Reasonable agreement was achieved. Based on the full scale predictions, it is suggested that the magnitude of flow velocities are technologically significant in terms of their effect on ferro-alloy immersion times and recoveries.

Heat transfer during the rewetting of hot horizontal channels

Abstract The heat transfer in the rewetting of hot horizontal channels is investigated. The physical model assumes an inclined rewetting front advancing at a uniform velocity. Precursory cooling in the dry region is considered. Three-dimensional energy equations are solved numerically by a finite difference method. Further, the axial and circumferential temperature distributions are predicted. The influence of various parameters on the rewetting velocity is analyzed, as are the variations of the different heat transfer mechanisms, convection to the fluid and conduction in the three-dimensions, as a function of time.

HEAT TRANSFER IN TURBULENT RECIRCULATORY FLOWS AFFECTED BY BUOYANCY FORCES IN RECTANGULAR CAVITIES

Abstract An analysis is carried out to investigate the heat transfer in a turbulent recirculatory flow affected by buoyancy forces. Transport equations for turbulence kinetic energy, energy dissipation Tate and mean square temperature fluctuations are derived and solved numerically together with the mass, momentum and energy conservation equations. The flow pattern and temperature distribution are shown for different Reynolds numbers. The buoyancy effect on flow pattern and temperature distribution is analyzed. Mean Nusselt numbers, with and without buoyancy effect are presented. Turbulence characteristics such as turbulence kinetic energy and effective viscosity arc discussed.