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The interference of a rearward facing jet on the flow over three representative afterbody shapes in a uniform subsonic flow
No full textThis report contains the results of an experimental investigation
into the interference of a ,rearward facing undeflected jet on the flow
over three afterbody shapes at subsonic speeds. The tests were performed
at a Reynolds number of 0.3 x 10(6) based on body diameter.
It was found that the form (or pressure) drag coefficient of the
bluff afterbody of a right cylinder increased appreciably with increase
in jet thrust coefficient. A similar but much smaller increase in form
drag was found on an ellipsoidal afterbody and a 'boat-tail'.
The effect of the jet was found to extend to approximately three
body diameters upstream of the jet exit but that beyond one body diameter
the effect was very small
Report to the worshipful company of coachmakers and harnessmakers. The digital simulation of a turbo-charged diesel engine
No full textA mathematical simulation of a, four stroke six cylinder
turbo-charged diesel engine vas used to study the changes in
performance caused by the variation of engine parameters and
operating conditions.
The principle variables were turbocharger size combustion timing and turbocharer bearing friction. The effect of these and other factors are tabulated and discussed. The results were explained in terms of the mathematical model employed and by comparison with the physical system.
The results suggest that the mathematical model behaves sensibly, in most cases, but that further development is required in order to incorporate the refinements which are necessary for an accurate simulation
Crack propagation in light alloys Ministry of Aviation contract no. PD/28/07
No full textThe revised approach to the measurement of the rate of crack propagation
in light alloys has entailed the development of new experimental techniques,
in particular the development of a multi-channel interval timer. The
design of this instrument and descriptions of the new techniques are
reported here together with the results of some preliminary evaluation tests
The relevance of the parameter yield strength to ultimate tensile strength ratio in sheet metal forming operations and a note on the importance of anisotropy in engineering applications
No full textA report on a series of tests carried out to determine the suitability of the grinding process for evaluating the efficiency of coolants to be used on the metal cutting processes process for evaluating the efficiency of coolants to be used on the metal cutting processes and also to evaluate the relative efficiency of 4 coolant samples for the drilling and turning processes
No full textA test programme was to be carried out to evaluate a series of
additives for use in industrial metal cutting coolants for use initially
on the turning, drilling and milling processes. These tests when they
take the form of tool life tests are costly in time and material and
where a shorter test can be reliably substituted for a life test, this
is most desirable. To this end the grinding process was included
in a pilot scheme to try to relate the grinding results to the drilling
and turning results. Milling was not used in this pilot scheme.
The grinding process has been very extensively studied at the
College of Aeronautics during the past 10 years and a reliable method
of evaluating the performance of grinding wheels and coolants has been
developed and proved in a very wide range of industrial applications.
The time required to evaluate a wheel or coolant sample is approximately
1 hour and the material consumed would be a few ounces in weight, hence,
the desire to interpret coolant efficiency for the metal cutting processes
from tests carried out using the controlled grinding process. (See
ref. 1)
The philosophy and principles of welding design
No full textThe welding designer requires a philosophy for his design responsibilities
and a thorough understanding of the basic principles in the subjects covering
his responsibilities. The education of the welding designer must provide a
spectrum of studies which will define these responsibilities and which will
help him to understand and apply the science and technology relevant to his
work
Milton Keynes: an outline cost-benefit study
No full textThis is a preliminary survey of some of the factors which would need to
be investigated in the design and cost-benefit analysis of alternative
transport systems for Milton Keynes. It outlines the framework within which
further work can be developed and provides some order-of-magnitude estimates
for basic elements in the transport cost-benefit equations
The mechanical properties of anisotropic polymers: Progress report no. 6
No full textPart 1
General Developments
The basic development work on the tensile creep apparatus was
completed by March, 1968. A description of the latest 'heavy-duty' creep
rig and two types of contraction extensometer, together with the relevant
creep trials, was given in Progress Report No. 5. Since then two further
'heavy-duty' creep rigs have been assembled and tested and are now ready
for use with rigid plastics. In addition, further trials of the double
transducer contraction extensometer described in Report No. 5 have been
carried out. These trials are described in part 2 of this report The
trials were considered reasonably satisfactory and each of the three heavy-duty
creep rigs has now been fitted with a device of this type in addition
to the normal tensile extensometer. The polythene creep rig described in
Progress Report No. 3 has been working satisfactorily for over a year and
no further modifications have been made in the period under review. At
the conclusion of the above-mentioned trials it was considered that the
creep apparatus was unlikely to require any further major changes. A
detailed report of all the apparatus has therefore been prepared with the
intention of submitting it for publication to the Journal of Scientific
Instruments. It is at present being examined at the Ministry of Technology.
(CoA Memo. No. 158)
Milton Keynes - preliminary estimates of regional traffic flows in 1981
No full textThe Milton Keynes Development Corporation and their planning
consultants have asked the College Transport Group to investigate the
scale of likely regional traffic flows into and out of Milton Keynes.
At this stage the emphasis is on providing information for the preparation
of a Master Plan for the city itself, rather than detailed traffic
estimates for planning transport systems in the surrounding region.
Population estimates for 1981 have been obtained from County
Councils for areas within a 20 mile radius of the new city, and the
proportions attracted to Milton Keynes for work and shopping assessed
using gravity model techniques. Separate estimates have been made of
work journeys from the city to regional employment and to London.
Possible upper and lower limits to these forecasts are included to
account for many uncertainties in the absolute and relative growth of
population, employment and shopping opportunities in the city itself and
in the surrounding region. The results are presented as traffic flews
into and out of octant sectors around the city. Flows to the east are
greater than to the west with work trip flows of the order of 2,500 person
trips each way in the most heavily loaded sectors. A 1981 city population
of 150,000 is likely to produce at least 1,500 daily commuters to London
using the fast rail service, with an additional 200 commuters from the region
using Milton Keynes railway station
The relevance of the mechanics of metal cutting to machinability
No full textINTRODUCTION
The process of metal cutting is a subject of great importance to
the makers and users of machine tools. Extensive research has gone
into the subject but has still left most of the phenomena unexplained.
Tool life is the main interest and before any real improvement in this
factor can be made, the basic metallurgical factors governing the
interaction between tool and workpiece must be better understood. Such
improvement can be effected through control of the wear process since
both tool and workpiece are metallic and machining is a process of
metal flow which is associated with a serious wear problem. The absence
of exact knowledge has however hampered empirical and mathematical
approaches to the problem.
Basically all machining operations are considered as either oblique
or orthogonal cutting, the former requiring three dimensions to specify
the geometry of the cutting part of the tool and the latter two. The
basic metal cutting process to be considered is that which is common,
in one form or another, to all metal cutting operations using a tool,
that of the wedge-shaped tool in fig. 1 (a-j) (1). Analyses of cutting
have been mainly concentrated on the relatively simple case of orthogonal
or two-dimensional cutting. Here the tool is so set that its cutting
edge is perpendicular to the direction of relative motion between tool and
workpiece and generates a plane parallel to the original work surface.
In doing this the tool removes a layer of material termed the chip.
One of the major objectives of metal cutting theory is the determination
of machining forces, chip geometry, tool life, energy consumption
and surface finish from a knowledge of the physical properties of the
workpiece and tool material and the cutting conditions alone. If this
could be achieved, lengthy chip measurements, delicate dynamometry, tedious
and costly tool life tests and surface finish measurements might be dispensed
with