CERES Community:
https://dspace.lib.cranfield.ac.uk:443/handle/1826/16
2016-07-25T06:11:49ZDevelopment of a method to study aircraft trajectory optimisation in the presence of icing conditions
https://dspace.lib.cranfield.ac.uk:443/handle/1826/10154
Title: Development of a method to study aircraft trajectory optimisation in the presence of icing conditions
Authors: Shinkafi, A.
Abstract: There is a growing demand for new technologies and
ight procedures that will enable
aircraft operators to burn less fuel and reduce the impacts of aviation on the environment.
Conventional approaches to trajectory optimisation do not include aircraft
systems in the optimisation set-up. However, the fuel penalty due to aircraft systems
operation is signi cant. Thus, applying optimised trajectories which do not account for
systems o -takes in real aircraft Flight Management System (FMS) will likely fail to
achieve a true optimum. This is more important in real scenarios where the ambient
conditions in
uence the systems operation signi cantly. This research proposed an ice
protection methodology which enables the development of a decision making process
within the FMS dependent on weather conditions; thus transforming the conventional
anti-icing method into a more intelligent system.
A case of a medium size transport aircraft
ight from London - Amsterdam under
various levels of possible icing was studied. The results show that fuel burn due to
anti-icing operation can increase up to 3.7% between climb and cruise altitudes. Up to
5.5% of this penalty can be saved using icing optimised trajectories. A 45% reduction
in awakenings due to noise was achieved with 3% fuel penalty. The novelty of the study
was extended using 3D optimisation to further improve
ight operations. It was found
that the simulation successfully changed the lateral position of the aircraft to minimise
the time spent and distance covered in icing conditions. The work here presents a
feasible methodology for future intelligent ice protection system (IPS) development,
which incorporates intelligent operation.2015-11-01T00:00:00ZShinkafi, A.Boundary layers with suction or injection
https://dspace.lib.cranfield.ac.uk:443/handle/1826/10088
Title: Boundary layers with suction or injection
Authors: Stevenson, T. N.
Abstract: Approximate integral equations are derived for the
compressible laminar boundary layer with arbitrary pressure
gradient and arbitrary suction or injection velocity through a
porous wall, Reasonable agreement is obtained when particular
solutions to the integral equations are compared with solutions
by previous authors.
Experiments in an incompressible turbulent boundary
layer over a porous surface reveal two laws for the inner and
cuter regions; laws which correlate previous experimental results.
The lams are used to calculate shear distributions and variations
of skin friction with Reynolds number and enable Preston tubes to
be used to estimate skin friction over a porous surface.
The outer region theory is extended to boundary layers
in small pressure gradients and at separation. The only universal
functions required are obtained from zero pressure gradient flow.
No other constants are used to calculate the mean velocity profiles
for boundary layers in small pressure gradients, with suction or
injection and at separation or reattachment. The theory agrees
with the available experimental results for turbulent boundary
layers in energy equilibrium.
Experiments in folly developed pipe flow show haw the
mean flow is altered when there is suction through a porous
section of the pipe. An approximate theory for the inner region
compares reasonably well with the experiments for small suction
velocities.1964-08-31T23:00:00ZStevenson, T. N.Non-equilibrium flow in plane expansion waves
https://dspace.lib.cranfield.ac.uk:443/handle/1826/10059
Title: Non-equilibrium flow in plane expansion waves
Authors: Cleaver, J. W.
Abstract: The non-equilibrium supersonic flow of a relaxing or reacting
gas through a plane expansion has been studied from a numerical,,
analytical and experimental point of view.
The flow of an ideal dissociating gas in a two dimensional
expansion has been solved numerically by writing the governing
equations of motion in their characteristic form.
In conflict with linearised theory along the wall, the
numerical solutions do not asymptote to the infinite rate equilibrium
values. To estimate how far the asymptotic state deviates from the
infinite rate equilibrium values, a formal second order solution has
been developed with the aid of transform techniques. An example has
been discussed for a simplified relaxing gas model, and estimates of
the asymptotic state have been obtained. An exact solution over the
whole field was not possible but by treating the parameter
as small, an approximate answer has been found.
To understand in more detail the coupling effects of two
relaxation processes, linearised theory has been extended to cope
with the flow of a gas with more than one relaxing mode. An example
has been discussed far Carbon Dioxide and the effect of possible
coupling between the bending and stretching modes of the molecule
in a plane expansion has been investigated.
The Mach-Zehnder interferometer and Schlieren method have
been used in conjunction with a 2" - diameter shock tube to study the
density and density gradients within, and following a sharp two-dimensional
expansion for shock heated Carbon Dioxide. Measurement
of the density gradient at the leading edge of the expansion by
quantitative Schlieren methods have allowed relaxation times to be
obtained. This method has the advantage that relaxation times can
be obtained for specific values of the density and temperature for
only small departures from an equilibrium state.1964-05-31T23:00:00ZCleaver, J. W.Optimum structures
https://dspace.lib.cranfield.ac.uk:443/handle/1826/10052
Title: Optimum structures
Authors: Hemp, W. S.; Chan, H. S. Y.
Abstract: The design of the best structure for a given purpose
depends upon the criterion used for optimisation. Structures
may be designed to safely transmit a given system of forces using
the least weight of material.. They may also be designed to have
maximum stiffness of a certain type for a given weight or
alternatively to have the greatest possible fundamental
frequency of vibration. These problems, although in general
distinct from one another, are closely related and much can be
achieved towards maximisation of stiffness and frequency by the
use of minimum weight designs. In fact it can be shown that a
minimum weight framework is the stiffest structure of that weight
for the force system, which it is designed to carry.x
The present report is concerned exclusively with the problem of
the design of structures of minimum weight, which are required
to transmit specified forces. Some attention will be given to
frameworks because, in particular, methods of approximate
numerical analysis are more readily formulated for this type of
structure, but the main emphasis will be placed upon the design
of structures formed from plates of variable thickness reinforced
by direct load carrying members.
See para,l.41965-06-30T23:00:00ZHemp, W. S.Chan, H. S. Y.