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It is well known that high-speed liquid jetting is one of the most powerful techniques available to cut or penetrate material. Recently, it has been conjectured that high-speed liquid jets may be beneficial in improving combustion in such applications as SCRAM jets and direct injection diesel engines. Although there are practical limitations on maximum jet velocity, a fundamental study of the characteristics of high-speed liquid fuel jets and their auto-ignition feasibility is necessary. Important benefits could be increased combustion efficiency and enhanced emission control from improved atomisation. The generation of high-speed liquid jets (water and diesel fuel) in the supersonic to hypersonic ranges by use of a vertical single stage powder gun is described. The effect of the projectile velocity and projectile mass on the jet velocity is found experimentally. Jet exit velocities from a range of different nozzle inner profiles and nozzle hardness are thoroughly examined. The characteristics and behaviour of the high-speed liquid jet and its leading bow shock wave have been studied with the aid of a shadowgraph technique. This provides a clearer picture of each stage of the generation of hypersonic liquid jets. It makes possible the study of hypersonic diesel fuel jet characteristics and their potential for auto-ignition. The fundamental processes by which a supersonic liquid jet is generated by projectile impact have been investigated. The momentum transfer from the projectile to the liquid and the shock wave reflection within the nozzle cavity are the key items of interest. A new one-dimensional analysis has been used in order to simplify this complex and difficult problem. The impact pressure obtained from the projectile was firstly derived. Then, an investigation of the intermittent pressure increase in a closed end cavity and a simple stepped, cross-sectional nozzle were carried out. The nozzle pressure and final jet velocity were estimated and compared to a previous method and to experimental results. Some interesting characteristics found in the experiments relate well to those anticipated by the analysis. The characteristics of a hypersonic diesel fuel jet and its leading edge shock wave were assessed for their potential for auto-ignition using fuel with cetane numbers from 50-100. The investigations were performed at normal ambient air and at elevated air (110 ???C) temperature. So far, there is no sign of auto-ignition that may occur because of the temperature rise of the induced shock.

Steel construction materials are very common use for factory and high building in nearly years. Generally speaking the steel construction material is refers has the fixed cross section the steel products. Like rolling H, the T section, the light channel steel, the angle steel and so on all are. But their order characteristic for depends on the length order, also can be different regarding the different length its unit weight price. Manages in not the easy situation in the present enterprise, saved the material cost already to change can it be that is often important, All company shall consider for its huge material storage. Regarding the company huge stock information bank system in, frequently the existence permits the material which how long year hasn't used, finally really very is big by the waste treatment regarding company's loss. So material cutting plane is an important work for those fabrication company. A good cutting plane is directly effect the used percentage, material cost, transportation cost, moving efficiency are also an important effects points, Therefore a good combination for cutting plan can obvious lower material cost, also good help for cutting efficiency, The research of Tabu search shall be use to steel construction material combination and becoming an good effective calculation method to reach three purpose as follow: 1.Considers the multi-objective of material fixed number of years, the spillage of material and the material cost, that material best arrangement combination solution or approximate best solution. 2.Develop algorithm for actuality using in materials combination so all fabrication company can use this method to reduce their cost. 3.Collection all remain material and make it together to save moving time. The result showed obtains the solution by the Tabu Search method to be possible the effective reduced material purchase quantity; also remainder centralism also has the very good improvement.

Thesis (M. Phil.)--University of Hong Kong, 1986.

Thesis (Ph. D.)--University of Hong Kong, 1988.

published_or_final_version / Industrial Engineering / Master / Master of Philosophy

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

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