DSpace Collection:
https://dspace.lboro.ac.uk/2134/10344
2016-09-26T09:14:52ZAttenuation of plane and high order modes in a circular and annular lined duct
https://dspace.lboro.ac.uk/2134/19756
Title: Attenuation of plane and high order modes in a circular and annular lined duct
Authors: Snow, D.J.
Abstract: An experimental and theoretical programme was undertaken to
measure and predict the attenuation of plane and spiral modes
within a cylindrical and annular duct. The duct was lined with a
partitioned absorber designed to act as a locally reacting surface.
A detailed duct modal theory was evolved for the cylindrical duct
and used to compare with the measured results. A thin annulus .
theory was adopted for the annular duct which made use of an
existing computer programme originally written for the
v
rectangular duct problem. (Ref 1-3).
The experimental work was conducted using a siren rig and also,
in order to obtain greater detail and reliability, a loudspeaker
rig was built and used extensively for the m = 0 and m = 1 modes.
These results confirm, within the limits of experimental accuracy ..
that the theoretical approach used is a valid one at least under
the prevailing laboratory conditions of zero mean air flow and
low sound pressure levels. Excellent agreem ent was obtained
between theory and experiment for the cylindrical duct. In the
case,-ยท of the annular duct the comparison was less satisfactory
but prOvided at least qualitative agreem ent.
The principle observed effects are the increase of attenuation
rate with increasing mode number and decreasing cut-off
frequency ratio.
The thesis is written wit ha. bias towards the problems of the
aero-engine industry and includes a brief account of present
day absorption technology in this field.
Description: A dissertation submitted as a requirement for the degree of MSc (by research).1971-01-01T00:00:00ZA study of the hydrodynamics of ACV hulls with particular emphasis on plough-in
https://dspace.lboro.ac.uk/2134/17317
Title: A study of the hydrodynamics of ACV hulls with particular emphasis on plough-in
Authors: Prasad, Rudrasena A.
Abstract: Since the major calm-water capsizes occurred in 1965/66,
much experimental work has been done to establish better
operational margins of safety. The general approach has
been to establish well defined limits of manoeuvrability
based upon available model and full-scale data. Mathematical
modelling of the ACV motion was used as a secondary approach
because the expressions involved are high in non-linearities
involving aerodynamic and hydrodynamic force terms of
similar orders of magnitude.
In this study, a numerical technique for the solution
of ACV non-linear equations is proposed and a two degree-of-
freedom model is built up using the digital simulation
language, SLAM. The simulation involved the use uf the
technique of storing values of the various non-linear functions
over a defined regime and then using these to provide updated
inputs as the craft changed its state. An ACV overturn sequence is studied by developing,
simulating and testing of equations describing the roll and
sideslip motion of the craft. In particular, the equations
take into account stiffness and damping forces associated
with both the hard structure and the craft cushion system;
inertial coupling effects due to craft deceleration are also
incorporated; induced trim effects due to the position of
the cushion wave system below the craft is modelled and
suitable phase lag is employed depending upon the deceleration
of the craft.
A basic configuration craft is chosen based upon critical
design parameters such as hull depth, skirt depth, VCG height
and hull angle of inclination. Extensive numerical testing of this
configuration is carried out involving a systematic method
of variation of the critical design parameters.
Results indicate that it is good philosophy to design ACV
hulls with planing capability applied to all faces of the hard
structure. The results also allow a set of ranges to be
established for the critical design parameters, which, if adhered
to will minimise the possibility of capsize for a craft
configuration of the type chosen for the study.
Description: A Masters Dissertation, submitted in partial fulfilment of the requirements of the award of Master of Science of Loughborough University.1978-01-01T00:00:00ZComputer analysis of wing design for general aviation aircraft
https://dspace.lboro.ac.uk/2134/16174
Title: Computer analysis of wing design for general aviation aircraft
Authors: Papadakis, Michael
Abstract: The calculation of the two dimensional viscous incompressible flow about
single and multielement aerofoil sections is considered.
A panel method, based on vorticity and source distributions is used for
the calculation of the potential flow. Once the velocity distribution is
known, integral boundary layer methods are employed to predict the viscous
effects. A wake model has also been developed for the calculation of the wake
behind the aerofoil system.
The solution is iterative. At the end of each iteration the velocities
on the aerofoil are corrected for viscosity and wake effects; the wake position
is also relaxed, before the next iteration starts.
The mathematical model of the flow, together with the computer program
written to test the model are described here in detail. The numerical results
obtained using the computer program are found to be in good agreement with
both experimental data and exact solutions.
Description: A Masters Dissertation, submitted in partial fulfilment of the requirements of the award of Master of Science of Loughborough University.1981-01-01T00:00:00ZThe performance and flow characteristics of a gas turbine combustor dump diffuser
https://dspace.lboro.ac.uk/2134/12691
Title: The performance and flow characteristics of a gas turbine combustor dump diffuser
Authors: Goom, Kevin A.
Abstract: Low speed tests have been carried out on a branched
diffuser, geometrically similar to that employed in some
gas turbine combustion systems. The fully annular test rig
consisted of a straight walled, axisymmetric pre-diffuser,
exhausting into a sudden expansion, the flow then being
divided into two separate streams by a bluff body simulating
the combustion chamber situated on the same centre-line as
the pre-diffuser. The overall area ratio was maintained at
2.0, and tests vJere conducted with fully developed entry
flo\~ for a range of pre-diffusers of 120 included angle, the
design value of the ratio of mass flows in the inner and
outer annuli surrounding the flame tube being fixed at 1.2.
Further tests were conducted using a single pre-diffuser, a
distorted entry velocity profile, and a design flow division
around the flame tube of 2.15....
Description: A Master's Dissertation, submitted in partial fulfilment of the requirements of the award of the Master Of Science degree of Loughborough University.1974-01-01T00:00:00Z