The influence of flow parameters on minimum ignition energy and quenching distance

Experiments have been carried out on the effects of pressure, velocity, mixture strength, turbulence intensity and turbulence scale on minimum ignition energy and quenching distance. Tests were conducted at room temperature in a specially designed closedcircuit tunnel in which a fan was used to drive propane/air mixtures at subatmospheric pressures through a 9 cm square working section at velocities up to 50 m/s. Perforated plates located at the upstream end of the working section provided near-isotropic turbulence in the ignition zone ranging from 1 to 22 percent in intensity, with values of turbulence scale up to 0.8 cm. Ignition was effected using capacitance sparks whose energy and duration could be varied independently

An investigation into high precision control of the relative angular position of two shafts over a range of speeds and ratios

SUMMARY The paper sets out to describe how a servo mechanism may be applied to generative gear grinding machines and an appropriate specification is drawn up. The system involves separate motor drives to the two shafts, the angular positions of which are monitored with radial diffraction gratings. One of the signals is frequency divided to achieve the speed ratio between the two shafts, the resultant similar frequency signals being phase compared, any difference producing an error signal thus completing the servo loop. Hydraulic motors are used as prime movers. The transfer functions of the loop are developed and compared with measured open loop results. It is clearly shown that with the components at present available the loop cannot be made stable. The specification of more appropriate hardware is discussed and future work outlined, but the conclusion is reached that this system cannot be used for its primary purpose on a generative gear grinding machine

Project P. 15

Summary System synthesis and analysis procedures were used to arrive at various conclusions about separation of functions, allocation of functions and, interface designs in a power station

Room temperature torsional fatigue properties of an iridium: 5% tungsten alloy

Introduction Fine wires of an iridium-5% tungsten alloy have been developed as a potential material for use in springs operating at high temperatures. Their suitability for such applications will to a considerable extent depend on satisfactory fatigue properties. The Materials Department of The College of Aeronautics was approached with a view to determining these torsional fatigue properties. This report covers preliminary work into this problem, namely the torsional fatigue behaviour of 0.020 ins. diameter wires at room temperature

The replica strain gauge technique

Surface deterioration and dimensional stability tests have been carried out on the low melting point replication alloy described in the first report. A range of alloys for the replication of surfaces at temperatures in the range 120 - 150°C has been prepared and evaluated. Preliminary studies of a cold pressing technique using fully annealed commercial purity aluminium as the replication material have shown that the technique has considerable promise for application over a wide range of temperatures

Push-pull fatigue properties of wires in an iridium - 5% tungsten alloy

Introduction This memorandum reports a series of tests to determine the fatigue properties of an iridium - 5% tungsten alloy at 600°c and 700°C. A previous memorandum, Memo. Mat. 61, reports the fatigue properties at room temperature of the same alloy

The time-dependent mechanical properties of fibre reinforced polymers

1. General Progress In the six months from April to September 1968 the task of primary importance has been to design lateral extensometers and to improve the longitudinal extensometer and consequently enable reproducable measurements of the deformations undergone by creep specimens to be made … [cont.]

The thermal degradation of epoxy resins (5)

A summary of work carried out between March 1968 and August 1968 on the resin hardener systems DDIVEP274, PA/EP274, LY558/HT973, EP274/Synolide 960, and CY175/HT907/DY065

Drilling system design project 1967: final report of frame design committee

This report outlines the recommendations of the Frame Design Committee for the final design of the machine, each major part of the structure being considered individually in the following sections : 1. Worktables 2. Guide and Slideways 3. Drill Head Support Structure 4. Swarf Disposal and Coolant Supply 5. General Constructio

The creep behaviour of fibre reinforced plastics

Synopsis: This paper describes the tensile creep behaviour of fibre reinforced plastics under a uniaxial stress system. In particular, unidirectionally and bidirectionally reinforced plastics are considered for the relative ease with which samples of them can be manufactured. A composite model that has previously been described 1, 2 is used as the basis of theoretical predictions of the variation of the creep compliance with certain material parameters. The parameters whose effects are examined are the volume fraction of the fibres, the distribution of fibre orientations, and the angle between a specified direction and the direction of application of a uniaxial stress system. Specimen experimental results are included to show the accuracy of these predictions and any shortcomings of the theoretical model are examined in the light of this comparison