Design of a Wind Tunnel Force Balance Aerospace Engineering

122 Pages·2017·2.09 MB·English

by  Andre C. Marta

Design of a Wind Tunnel Force Balance
João Tiago Pinheiro Fernandes
Thesis to obtain the Master of Science Degree in
Aerospace Engineering
Supervisor: Prof. André Calado Marta
Examination Committee
Chairperson: Prof. Filipe Szolnoky Ramos Pinto Cunha
Supervisor: Prof. André Calado Marta
Member of the Committee: Prof. João Manuel Gonçalves de Sousa Oliveira
June 2018
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Dedicatedtomyfamilyandfriends.
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Acknowledgments
Firstly,Iwouldliketothanktomysupervisor,ProfessorAndre´ Marta,forthewiseguidanceandpatience
duringthelastmonths,evenwhenthingsseemedtofailtogoasplanned.
This thesis is the milestone of a period of hard-work and dedication that started a few years ago.
Throughout this path, I’ve met extraordinary people without whom this trajectory would not have been
as bright as it was. I would like to thank to my friends Marta for all the support and advices and Rute
for the working spot and all the helpful writing tips, with whom I share the adventures of working in a
demandingmasterthesis.
IalsowanttoexpressmygratitudetomyspecialfriendsCla´udiaandRitaforthecoffeebreaksand
forthemomentsoflaughterandjoythatkeptmepreparedforanotherroundofintensivework.
Allthisworkwouldnothavehavebeenpossiblewithouttheunconditionalsupportofmylovingfamily.
Especially to my mother, for being truly understanding and for showing support in the moments when
I needed it the most, to my father that supported my work with his technical expertise and for always
havingasolutionandtomybrotherandgrandparentsfortheloveandcare.
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Resumo
Os tu´neis aerodinaˆmicos sa˜o usados para simular o comportamento de modelos na presenc¸a de um
escoamento, permitindo obter as componentes que melhor definem essa interac¸a˜o, as forc¸as e os
momentos. Para tomar total partido do tu´nel aerodinaˆmico presente no Laborato´rio de Engenharia
Aeroespacial do Instituto Superior Te´cnico, revelou-se necessa´rio projetar uma balanc¸a de forc¸as e
momentos.
Em primeiro lugar, o dimensionamento da balanc¸a baseou-se-se na possibilidade de realizac¸a˜o
de testes em modelos de aeronaves e de meia asa montados na secc¸a˜o de teste, recorrendo a um
software de simulac¸a˜o (XFLR5) que permitiu obter a gama ma´xima de carregamento a que a balanc¸a
estara´ sujeitaparacadaumadashipo´teses.
Omodelodabalanc¸afoiselecionadoutilizandoumconjuntodecrite´rioscomparativoserecorrendo
aoProcessoHiera´rquicoAnal´ıticoquepermitiudefinir,deentreasarquitecturasdebalanc¸asdeforc¸as
mais comuns, a que se revelou mais adequada (balanc¸a externa em plataforma). Uma vez definido
o modelo que constitui o “esqueleto” da balanc¸a de forc¸as, foi necessa´rio projetar, criteriosamente,
cada um dos seus componentes mecaˆnicos e verificar a sua integridade, atrave´s do uso do software
de modelac¸a˜o SolidWorks. Seguiu-se a selec¸a˜o de todos os componentes eletro´nicos como os ex-
tenso´metros e o sistema de aquisic¸a˜o de dados que permitira˜o averiguar a deformac¸a˜o da balanc¸a
causadaporumdadocarregamento. Foramfeitas, ainda, algumasconsiderac¸o˜esacercadoprocesso
de montagem e foi apresentado o custo total estimado da balanc¸a de forc¸as. Por fim, sugere-se um
procedimentodecalibrac¸a˜oquepermitetornarabalanc¸aoperacional.
Palavras-chave:
Balanc¸aaerodinaˆmicadeseiscomponentes, Ensaiosexperimentais, Pro-
jetomecaˆnico,Sensoreseinstrumentac¸a˜o,Procedimentodecalibrac¸a˜o
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Abstract
Wind tunnels are used to simulate the behaviour of models in the presence of an airflow thus allowing
to obtain the components that better define this interaction, forces and moments. In order to take full
advantage of the Aerospace Engineering Laboratory’s wind tunnel at Instituto Superior Te´cnico, it has
provednecessarytodesignabalancetomeasureforcesandmoments.
Firstly, the force balance dimensioning was based in the possibility of testing both aircraft and half-
wing models that fit the wind tunnel test section, using a simulation software (XFLR5) to obtain the
maximumloadrangetheforcebalancehastobeabletosupportineachofthesituations.
The Analytic Hierarchy Process and a set of comparison criteria allowed the selection of the most
adequateforcebalancearchitecturefromthemostwidelyused,theexternalplatformbalance. Oncethe
“skeleton”oftheforcebalancewasdefined,itwasnecessarytocarefullydefineeachofitsmechanical
componentsandguaranteethatitsintegritywasfulfilledusingthesoftwareSolidWorks. Thisisfollowed
by the selection of all the electronic components like strain gauges and data acquisition system that
willassessthedeformationofthebalanceforacertainloadingcondition. Severalconsiderationsonthe
mechanicalassemblyweremadeandacostanalysiswaspresented. Finally,itissuggestedacalibration
proceduretomaketheforcebalancefullyfunctional.
Keywords:
Six components aerodynamic balance, Experimental testing, Mechanical design,
Sensorsandinstrumentation,Calibrationprocedure
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