Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619129
Title: Aerodynamics, stability and shape optimisation of unmanned combat air vehicles
Author: Coppin, Joe
ISNI:       0000 0004 5356 8038
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2014
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Abstract:
Unmanned Combat Air Vehicles have been proposed for future military roles. The shape of these vehicles is driven by stealth requirements and is often aerodynamically compromised. This results in designs which struggle to meet their take-off lift requirements without experiencing flow separations and unacceptable instabilities in the pitch or yaw axis. This work aims to better understand the aerodynamics of these vehicles as well as develop methods to generate improved designs. An in depth RANS analysis has been completed for the Boeing 1303 UCAV concept with validation from QinetiQ 5m and ARA transonic wind tunnels. Two flow solvers and various turbulence models have been used. Longitudinal and directional stability have been investigated, looking at total and spanwise forces, pressure distributions and flow visualisation. The effects of modelling assumptions has also been studied. This has helped to better understand the underlying flowfield and has given some indication as to how the design may be improved. A novel design methodology has been developed and applied to the 1303 UCAV aiming to minimise drag at cruise while ensuring the leading edge flow remains attached at take-off. This is based on an a sequential quadratic programming (SQP) optimiser where objective function (CD) is calculated with an in house solver MERLIN and the gradients are calculated in an efficient manner using a discrete adjoint solver adjoint-MERLIN. High lift constraints were applied based on Lan's Quasi-Vortex-Lattice Method with an experimentally derived limit on attainable leading edge thrust. The geometry was parametrised with Bézier-Bernstein polynomials combined with the Class Shape Transformation method for improved geometrical control near the leading edge. Various designs were produced giving some indication of the trade-off between cruise and high lift performance as well as limitations to the method. The method has proved to be good for generating balanced designs however higher lift designs suffer from lower surface separation at cruise.
Supervisor: Qin, Ning Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.619129  DOI: Not available
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