Parametric Design, Aerodynamic Analysis and Parametric Optimization of a Solar UAV Aerospace ...

114 Pages·2014·11.84 MB·English

by  Andre C. Marta

Parametric Design, Aerodynamic Analysis and Parametric
Optimization of a Solar UAV
Nuno Miguel António Silva
Thesis to obtain the Master of Science Degree in
Aerospace Engineering
Supervisors: Professor André Calado Marta and Doctor José Manuel da Silva Chaves
Ribeiro Pereira
Examination Committee
Chairperson: Professor Fernando José Parracho Lau
Supervisor: Professor André Calado Marta
Member of the Committee: Professor Filipe Szolnoky Ramos Pinto Cunha
June 2014
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Tomyparents. Fortheirloveandsupport.
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Acknowledgments
Mymostsincerethanksto:
First and foremost, my supervisors Professor Andre´ Calado Marta and Dr. Jose´ Manuel da Silva
Chaves Ribeiro Pereira for their patience, guidance and support throughout the period it took me to
completethisthesis.
LASEFfortheuseofitsinstallationsandresources.
The LASEF team that relentlessly helped me when any technical adversities occurred when using
theirequipmentinordertoperformalltheaerodynamicsimulations.
Myfamilyandfriendsfortheirconstantsupportandbeliefinmethroughtheyears.
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Resumo
OobjectivodestatesefoidesenvolverumaferramentaCADquefac¸ausodescriptsporformaadesen-
har diferentes configurac¸o˜es de UAVs e a posterior ana´lise aerodinaˆmica dessas configurac¸o˜es. Com
recurso ao Star-CCM+ analisou-se um UAV em particular. O UAV de estudo consiste num Long En-
duranceElectricUAV(LEEUAV).OLEEUAV,foisubmetidoaumase´riedeestudosaerodinaˆmicosonde
se usou os modelos de turbuleˆncia Spalart-Allmaras e k−ω SST, este u´ltimo usado em conjunto com
o modelo de transic¸a˜o γ −Re , e os seus resultados comparados com dados experimentais. Apenas
θ
o modelo de turbuleˆncia k −ω SST em conjunto com o modelo de transic¸a˜o γ −Re foram usados
θ
nas simulac¸o˜es aerodinaˆmicas mais detalhadas. Em voo cruzeiro, o LEEUAV apresenta uma raza˜o
de finesse de 14.01, velocidade de perda de 6.21 m/s e velocidade ma´xima em voo cruzeiro de 29.3
m/s. Para melhorar a performance do LEEUAV implementaram-se estudos parame´tricos a` forma do
nariz, asa e fuselagem. Com a modificac¸a˜o da forma do nariz, os gradientes de pressa˜o adversos a´ı
localizados foram eliminados ou diminu´ıdos. Com a ponta da asa arredondada reduziu-se em 3 cm
as bolhas de separac¸a˜o laminares na asa. Modificando a geometria da raiz da asa eliminou-se uma
zonadeescoamentoseparadoquesegeravaapartirdos2o. Diminuindooaˆngulodeincideˆnciadaasa
permitiu-seocontroloatrave´sdeaileronsate´ pelomenos10o.
Palavras-chave:
UAV Solar, Longo Alcance, Propulsa˜o H´ıbrida, CFD, CAD, Modelac¸a˜o
Parame´trica,Ana´lisedeSensibilidade.
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Abstract
Theaimofthisthesiswastodevelopandimplementacomputationalprocesstoenabletheswiftdesign
ofdifferentUAVconfigurationsandtheiraerodynamicanalysis. Tothisend,aCADtoolusingscriptswas
adoptedtodefinetheUAVexternalshapewhichwaslaterimportedintoaCFDtooltogeneratesuitable
meshes. The test case consisted of a Long Endurance Electric UAV (LEEUAV), that was aerodynam-
ically analyzed and parametrically optimized. While performing the aerodynamic analyses, turbulence
modelsSpalart-Allmarasandk−ω SST,thelaterbeingemployedintandemwiththeγ−Re transition
θ
model,wereemployedandtheirpredictionscomparedwithexperimentaldata. Onlythek−ω SSTtur-
bulencemodelandtheγ−Re transitionmodelwereemployedinthedetailedaerodynamicsimulations.
θ
During cruise, the baseline LEEUAV presents a lift-to-drag ratio of 14.01, stall speed of 6.21 m/s and
maximumcruisespeedof29.3m/s. Toenhancethebaselinecruiseperformance,aseriesofparamet-
ricoptimizationandsensitivitystudieswereperformedwhereitsnose, wingandfuselageshapeswere
modified. With the nose shape modification proposal, the adverse pressure gradients that previously
existed in that surface were reduced. With rounded wingtips, the wing long laminar separation bubbles
werepredictedtodecrease. Withtheproposedwingrootfairing,aregionofseparatedflowthatformed
beginning at 2o disappeared thus reducing the aircraft drag. With the proposed wing washout, aileron
controleffectivenesswasextendedtoanglesofattackupto10o.
Keywords:
SolarUAV,UAVAirframe,LongEndurance,HybridPropulsion,ComputationalFluid
Dynamics,Computer-AidedDesign,ParametricModeling,SensitivityAnalysis.
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