published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

Thesis--M. Sc. (Eng.), University of Hong Kong. / Mimeographed.

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In the present work, investigations are carried out for the ultimate use of the "Bis table Fluid Amplifier" as an alternator to produce intermittent vertical water slugs. The effect of some geometrical and flow variables on the amplifier characteristics used in a vertical position, is studied experimentally. The minimum control flow required to switch the main power jet from one wall to the other is obtained as a function of the main jet flow rate, the splitter angle and its distance from the main nozzle. The efficiency of the amplifier functioning as a pressure recovery device is determined in relation to the output load. Theoretical and experimental results are compared. Some aspects of downwards air water flow in long vertical tubes are investigated. The formation of a spherical-cap air slug in an overflow pipe, and the behaviour and stability of the air-water interface in the tube are studied with the aid of motion picture films. Finally, a theory is appended concerning the transient polytropic compression of a gas in a vertical tube by a high velocity falling liquid slug from a constant flow supply.

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The effects of internal dimensional variations on the switching and recovery performance of an or/nor gate are investigated. A large scale experimental model is observed for switch pressure and flow rate, return pressure, and output recovery pressure in relation to variations in wall length, control and vent width, wall offsets, and splitter distance. For each dimensional configuration, effects of 1- and 3-nozzle loads are examined over Reynolds numbers (based on power supply nozzle exit width) of 2500 to 4000. The nominal design yields high switch pressures (> 20% of supply) and flow rates, and exaggerated load and Reynolds number dependence. Results of the individual dimensional variations show the control width to display the greatest effect on switching, with attachment wall offset and wall length having less significance. Opposite wall and splitter variations show negligible effects over the range examined. A revised design is obtained by combining the dimensional variations which show desirable performance trends. An analytical model is described which agrees reasonably well with the experimental data with some empirical correlation. / Master of Science

Small dimensional changes in six parameters were experimentally studied for their effects on the performance of the bistable fluid amplifier. These dimensional parameters were offset, wall length, control width, power nozzle width, wall flat, and power nozzle shape. The investigation was conducted on a ten times actual size model of a typical, commercially available amplifier. Data were taken for operating conditions of 1 nozzle load and blocked outputs over a range of Reynolds numbers (based on the nominal nozzle width) of 2000 to 6000. Evidence in support of the hypothesis of the coexistence of two, different level, overlapping switch points was presented. The hypothesis was used to explain unusual behavior and to fit smooth and regular curves to the experimental data obtained. The center of the investigation was the six tables of data generated and the method used to obtain figures of the specific dimensional characteristics desired by the user. It was found that the overwhelming influence of operating conditions (Reynolds number and output loading) prevented specific discussion of dimension characteristics without having the user's specific needs or operating conditions specified. From a broad or general look at the dimensional characteristics, it was found that wall-length had the most severe characteristics. It was also found that the wider control width promoted a clean and well-behaved switch absent of two coexistent switch points. For reasons unknown, it was found that the shorter power nozzle shapes made the device extremely sensitive to bias. / Master of Science