Student Number : 9803192Y -
MSc(Eng) Dissertation -
School of Mechanical, Industrial and Aeronautical Engineering -
Faculty of Engineering and the Built Environment / A computational °uid dynamics (CFD) study was carried out to improve the aero-
dynamic performance of an agile high angle of attack missile. The normal force
generated by the missile strakes had to be increased at the low angles of attack and
the large side forces, experienced at high angles of attack due to the formation of
steady asymmetric vortices had to be eliminated using strakelets on the missile nose.
The ¯rst objective was achieved by increasing the missile strake span from 0:06D to
0:13D. The larger strake span increased the e®ective diameter of the missile body
and prevented °ow reattachment to the body, a problem that was experienced when
the strake span was 0:06D. Due to °ow separating further away from the body,
strong vortices formed on the missile strakes, resulting in an increase in the normal
force generated by the missile strakes at low angles of attack. The second objective
was two-fold. Prior to analysing the e®ect of the strakelets on a steady asymmetric
°ow¯eld, the steady asymmetric °ow¯eld had to ¯rst be created. This was achieved
by placing a permanent, geometric perturbation on the missile nose. The size of
the perturbation used in the study, which was determined by an iterative process,
did not force °ow separation at low angles of attack and resulted in a steady asym-
metric °ow¯eld that was representative of that on a blunt-ogive body. The e®ect
of changing the span of the strakelets and the axial position of the strakelets were
then investigated. It was found that the strakelets with a span of 0:09D, placed 1D
from the nose tip eliminated the side forces by forcing vortex symmetry. Increasing
or decreasing the span of the strakelet, positioned 1D from the nose tip or placing
the strakelets with a span of 0:09D closer or further away from the nose tip did not
eliminate the steady vortex asymmetry.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/2152 |
| Date | 28 February 2007 |
| Creators | Kistan, Prevani |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 4845560 bytes, application/pdf, application/pdf |
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