Thesis (Ph. D.)--Lehigh University, 1996. / Includes vita. Bibliography: leaves 276-284.

Thesis (doctoral)--Rheinische Friedrich-Wilhelms-Universität Bonn, 1996. / Includes bibliographical references (p. 94-99).

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 202-212).

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This paper presents the methods of predicting the steady-state two-phase flow (steam and water) pressure drop across the restrictions of annular geometries formed when tubes extend through circular holes in tube support plates. Two approaches are discussed and a detailed sample calculation of the one selected is presented. The major areas of discussion are the orientation of tubes-to-tube support plate holes, and the thickness of tube support plate. Finally, the conclusion gives a comparison of methods and recommendations for future investigations.

The flow patterns of an air-water mixture at atmospheric pressure were visually observed through a simulated vertical steam generator tube support plate of circular hole and trefoil designs. Flow oscillations with a period on the order of 0.4 seconds were observed in both support plates at similar mass flow rate combinations. The oscillation consisted of a period of rapid surging followed by a low flow or stagnation period on the order of 0.1 seconds. Reverse (downward) flow was also observed for part of the oscillation cycle in the trefoil support plate. The flow oscillations that exist in one tube support plate are coupled to the oscillation phase that exists in the preceding tube support plate. The operation of a steam generator in a region where this flow oscillation occurs could result in reduced to steam generator life due to increased corrosion.

This work firstly reviews the experimental data for centrifugal pumps operating in steady-state and transient two-phase flow. The pump head and torque become degraded in two-phase pumping operation. This degradation becomes increasingly severe and abrupt as pump specific speed falls, and is chiefly due to the reduced impeller performance. Degradation depends primarily on specific speed and pump geometry, void fraction and flow coefficient. Degradation also depends on flow regime, fluid viscosity, flow rate and system pressure. The evidence suggests that transient pump performance can be accurately predicted by steady-state tests.A pseudo-two-dimensional analysis is then presented of two-phase flow through a centrifugal pump to predict the head and torque performance over the full range of operating conditions. The loss of performance in the impeller in pumping operation is caused by the large slip that develops between the two phases as the gas slows dramatically compared to the liquid, particularly in stratified flow. In these conditions there is little or no pressure recovery by diffusion in the pump casing, with further energy losses at the impeller exit due to flow impact against the casing.The head and torque performance predicted by the model compared favourably with the results from the single-phase and two-phase experimental pump tests. The comparisons cover all 4 quadrants of pump operation over the whole voidage range for a comprehensive range of pump designs and fluid mixtures. A number of recommendations are made to improve two-phase pump performance for industrial applications.