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A leak detection system for pipelines was developed by using artificial neural networks (ANN) for leak sizing and location and by processing the field data. This system can detect and locate leaks down to 1% of flow rates in pipelines carrying hazardous materials in about 100 s. A reference pipeline was considered for practical implementation of the package. The ability of the package to withstand spurious alarms in the event of operational transients was tested. The compressibility effect, due to packing of the liquid in the pipeline, causes many such spurious alarms. Adequate preprocessing of the data was performed by using a computer code in conjunction with the ANN to compensate for the operational variations and to prevent spurious alarms. The package detects leaks as small as 1% of the inlet flow rate and correctly predicts the leaking segment of pipeline with a probability of success that is greater than 50% for the smallest leak. In all cases, the timely response of the system was seen as a major advantage.

Measurements of the effect of liquid viscosity on the initiation of roll waves in a horizontal gas-liquid flow are presented. These results are interpreted by an analysis based on the calculation of the growth of long wavelength disturbances.

The point of onset of large disturbance waves and droplet entrapment has been determined for the annular downward flow of air-water mixtures in a 24 mm ID tube. Experimental results are in a good qualitative agreement with the previous work by Webb and Hewitt1. These results indicate that 1the critical gas velocity at the onset of entrainment is lower than the value predicted by available correlations 2the critical gas velocity continuously decreases at increasing the liquid Reynolds number 3below a liquid Reynolds number of 270 no entrainment occurs even at gas velocities as high as 80 m/sec A correlation for the critical gas velocity which is based on a simple physical model of atomization, is also proposed.

New measurements are presented for film height and pressure drop for vertical gas-liquid annular flows. Improved methods for predicting the film height and interfacial friction factor are developed for situations in which the liquid film flow rate is known.

Downward annular two-phase flow (air-water) has been examined experimentally. Statistical methods have been applied to calculate the flowrates associated with the hypothetical substrate flow and large wave flow. Agreement with actual Jiquid flowrates under varying gas flows is good. The constant thickness assumption is shown to give significant error. Main characteristics of large waves have also been determined. L'ecoulement biphasique annulaire descendant (air-eau) a ete etudie experimentalement. Des methodes statistiques ont ete appliquees aux calculs des debits associes a l'ecoulement hypothetique du substrat et a l'ecoulement de grandes ondulations. L'accord avec les debits reels en presence de differents ecoulements gazeux est bon. L'hypothese d'une epaisseur constante s'est averee impliquer une erreur importante. Les principales caracteristiques des grandes ondulations ont egalement ete determinees.