No description available.

A review was carried out which revealed that no simple mathematical model was available which could be used to predict the performance of a centrifugal pump when it is operating under two phase flow conditions. Experimental analyses were carried out to aid the development of such a model. A rotating channel test rig was designed to study the structure of airwater flow through an impeller passageway. The observations generated a large amount of qualitative data. A full scale centrifugal pump was also tested which provided data that allowed the results of the rotating channel experiments to be considered in more quantitative terms. These two sets of experimental work allowed a conceptual model of the two phase flow through a centrifugal pump to be constructed. The model assumes that forces act on the bubbles as they pass through the impeller passageway because of the rotation and the curvature of the impeller passageway. These forces cause the bubbles to decelerate and coalesce creating a stationary air void which leads to a partial blockage of the channel. This causes the velocity of the fluid passing through the pump to be modified. The model uses a onedimensional velocity vector approach adjusted for hydraulic losses to calculate the head raised by the pump under such conditions. The model presented provides the basis upon which a predictive tool could be developed and used in the development engineering environment. Currently operational problems that arise because of two phase flow are often quantified using scaled hydraulic models, which are expensive, or within the actual application where costly engineering solutions may be required to give acceptable performance. A mathematical model is a much more cost effective tool and its application allows the engineer to decide whether system performance would be compromised by the two phase conditions encountered and propose possible solutions. In recommending the development of such a model it is necessary to consider where and how in the project cycle it should be used. A number of companies were canvassed and it was concluded that in many cases such models are used too late in the project cycle to provide maximum return. In the case of projects which include participants from a number of companies it is suggested that an inter-company team should be constructed if development models are to be widely used. This team should be used to plan and implement the use of development models efficiently and ensure that the data produced is communicated effectively and is of the maximum value to the participants.

During micro packaging process, the products are almost manufactured by hand work. The development of the micro packaging system can reduce human error and automatic process is implemented. This paper describes a method of motion planning of sliding, and rotating manipulations by a adjustable gripper. In precision assembly tasks such as a screw insertion, the task accuracy required for each direction in the task space is different. This paper discusses the adjustable gripper applied on automatic assembly system. The accurate determination of the position and shape of the objects are analyzed and identified by machine vision. The package time is reduced and the product yield rate is raised.

This study experimentally investigates the effects of rotation, the buoyancy force, and the channel aspect ratio on heat transfer in two-pass rotating rectangular channels. The experiments are conducted with two surface conditions: smooth walls and 45?? angled ribbed walls. The channel aspect ratios include 4:1, 2:1, 1:1, 1:2 and 1:4. Four Reynolds numbers are studied: 5000, 10000, 25000 and 40000. The rotation speed is fixed at 550 rpm for all tests, and for each channel, two channel orientations are studied: 90?? and 45?? or 135??, with respect to the plane of rotation. Rib turbulators are placed on the leading and trailing walls of the channels at an angle of 45?? to the flow direction. The ribs have a 1.59 by 1.59 mm square cross section, and the rib pitch-to-height ratio (P/e) is 10 for all tests. The effects of the local buoyancy parameter and channel aspect ratio on the regional Nusselt number ratio are presented. Pressure drop data are also measured for both smooth and ribbed channels in rotating and non-rotating conditions. The results show that increasing the local buoyancy parameter increases the Nusselt number ratio on the trailing surface and decreases the Nusselt number ratio on the leading surface in the first pass for all channels. However, the trend of the Nusselt number ratio in the second pass is more complicated due to the strong effect of the 180?? turn. Results are also presented for this critical turn region of the two-pass channels. In addition to these regions, the channel averaged heat transfer, friction factor, and thermal performance are determined for each channel. With the channels having comparable Nusselt number ratios, the 1:4 channel has the superior thermal performance because it incurs the least pressure penalty. In this study, the author is able to systematically analyze, correlate, and conclude the thermal performance comparison with the combination of rotation effects on five different aspect ratio channels with both smooth walls and rib turbulated walls.

Thesis (Ph. D.)--York University, 1999. Graduate Programme in Philosophy. / Typescript. Includes bibliographical references (leaves 143-148). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ43451.

Inaug.-diss.--Marburg.

Inaug.-diss.--Göttingen. / Lebenslauf.

Thesis--Ph. D., University of Hong Kong. / Mimeographed.

In rotating machinery there exist mechanical and electrical losses. With the advent of more efficient power-electronic devices, the shift has been towards reducing mechanical losses. There are solutions that exist, such as air bearings and oil-mist bearings that go some way to reducing these losses. In order to produce an even more efficient machine, windage losses must be reduced. This can be achieved by placing the machine in a vacuum. It becomes clear, therefore, that the bearing system can only be of the magnetic type. An area of research interest that has developed as a result of higher-efficiency machines is that of flywheel-energy storage systems. The most effective machine for flywheel energy storage is the permanent-magnet machine. This does not require external excitation for motoring or generating and is easier to operate as a generator than an induction machine. In this work a permanent-magnet synchronous machine is designed and constructed, with the aid of finite-element analysis. The rotor is a novel design which uses six magnets in a two-pole configuration. This gives a rotor which is mechanically and magnetically good, yet it does not require the use of a can. The testing of this machine shows a good correlation between predicted and measured results. When a permanent-magnerto tor is placed in bearingst hat allow it to move radially, there exists an unbalanced magnetic pull between rotor and stator. These forces are predicted using a finite-element method and then measured. These results are then used as a basis . for the design of an active magneticb earing The magneticb earingw as found to be able to 0 C7 cope with these forces. The magnetic bearing itself was used as a novel way of measuring the unbalanced magnetic forces, which required no contact between the rotor and the transducer.

No description available.