Journal of Mechanical Engineering Science

Measurements have been made of the amounts of cold and heat produced by a vortex tube operated with methane containing some carbon dioxide, and with Algerian natural gas, which has a high methane content. The effects of gas supply temperature and pressure have been investigated. The contribution of the Joule–Thomson effect to the total cooling has been calculated and allowed for.

Vortex effect cooling decreases with lowering of the supply temperature and probably disappears at the gas liquefaction point. It is dependent on the pressure expansion ratio across the tube. The findings are compared with those of other workers and those predicted by vortex tube theories.

When calculating the flow through turbomachines by an iterative procedure, it is assumed that on each cycle of iteration there is only one solution for the flow pattern. The uniqueness of the solution obtained by the method of streamline curvature is examined and a set of Mach number conditions are derived which are sufficient to ensure that the flow pattern is unique. The Mach number limitations are the same as those which are necessary to avoid ambiguity in the matrix through-flow analysis. An alternative procedure is then described in which the solution for the flow pattern is always unique.

Hydraulic vibrators which are powerful, cheap and compact are described and theory for their performance prediction is given. They are of use where high forces are required on structures of high dynamic stiffness at frequencies up to 1 kHz.

The trend in modern plain journal bearing design is towards a reduction in the relative bearing width; this results in reduced machine bulk and bearing losses, but has the disadvantage of increased bearing wear, particularly at starting, stopping and the reversal of motion.

A method of reducing this wear problem is by means of hydraulic jacking, or the separation of the load carrying surfaces by the introduction of high pressure oil into the clearance space, through suitable feed grooves.

The article describes an analytical solution to the problem of hydraulic jacking. The following solutions are presented, giving full performance characteristics.

(1) Single- and twin-axial feed grooves, end leakage neglected.

(2) Single- and twin-axial feed grooves, concentric journal, finite length bearing (approximate solution).

(3) Single- and twin-axial feed holes, concentric journal, small diameter feed holes (approximate solution).

Some experimental verification is given for the theory of the axial feed groove arrangement, both the single grooved and the twin grooved arrangement.

A new test for investigating biaxial creep in sheet metal is described. The specimen is a thin circular diaphragm clamped at the edge and deflected by lateral hydrostatic pressure. Stress and strain in the central region of the specimen are determined from measurements of pressure and of extension and curvature at the pole.

An analysis of the time-dependent deformation of a circular diaphragm is presented and compared with experiments in which commercial purity aluminium sheet was tested in constant pressure tests at temperatures between 100 and 250°C. The biaxial creep data were compared with the results of uniaxial constant load tests, but no satisfactory correlation could be obtained. The results of constant pressure biaxial tests at different temperatures above 175°C could be correlated using the Zener–Holloman time parameter.

A class of epicyclic gears based on coaxially mounted plane trains is defined. The class is restricted to those gears in which planetary gears of adjacent trains are coupled.

The type of epicyclic multi-ratio gearbox in which the input and output members are always the same is selected for consideration. The basic kinematics of the planetary member are then reduced to a single equation which is subsequently expressed as a chart, covering all ratio possibilities and directly applicable as the basis of synthesis. The chart is shown to offer an arbitrary means of describing the various forms of gear by a number-and-letter code.

The application of the chart to the synthesis of trains incorporating planetary idlers and multi-ratio trains is explained.

In Part 1, the slip-line field solutions and the associated load requirements necessary for the indentation of anisotropic solids are presented. The analysis is based on Hill's approach to the analysis of anisotropic material. All results are recorded in terms of a lumped anisotropic parameter, c.

In Part 2, the results of an investigation to determine the anisotropic parameters of a commercially available aluminium are reported. Specimens machined from the aluminium at selected orientations to the anisotropic axes were indented using a nominally frictionless flat rectangular punch. A comparison between the theoretical and experimental indentation loads is given.