Piezoelectric Energy Harvesting for Flow Control in Fixed-Wing Micro Aerial Vehicles Aerospace

102 Pages·2016·18.38 MB·English

by  Andre C. Marta

Piezoelectric Energy Harvesting for Flow Control in
Fixed-Wing Micro Aerial Vehicles
Sérgio Ricardo Sumares Souteiro
Thesis to obtain the Master of Science Degree in
Aerospace Engineering
Supervisor: Prof. João Manuel Melo de Sousa
Examination Committee
Chairperson: Prof. Fernando José Parracho Lau
Supervisor: Prof. João Manuel Melo de Sousa
Member of the Committee: Prof. Filipe Szolnoky Ramos Pinto Cunha
July 2016
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Dedicatedtomybelovedfamilyandfriends
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Acknowledgments
First and foremost, I would like to thank my supervisor Professor Joa˜o Manuel Melo de Sousa, for
theguidance,supportandinterestthatallowedmetoreachasfarasIdidinthiswork. Hispatiencewas
veryimportantduringthemonthsittookmetocompletethisthesis.
Also, I would like to express my great thanks to all my friends and family for their love and support
eversinceIneededit. Theirhelphasbeenimportantformyentireacademicpathbutspeciallyoverthe
lastfewmonthsofcompletingthisthesiswascrucial.
I would like to thank my girlfriend for cheering me up when I needed it most and for being always a
supportiveforcewhileIwasdoingthiswork.
A special note to my mother. She is the one who ever believed in me and always did everything for
mesoIcouldreachmydreamsandgoals. EvenwhenitlookedthatIfailed,shewastheretoshowme
therightway. Thisworkistheresultofyourefforts. Thankyoumum!!
Withoutthehelpandsupportfromthisbiggroupofpeople,thisprojectandmyacademicpathwould
nothavebeenpossible. Thankyoueveryone!
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Resumo
Nos u´ltimos anos, a procura de Micro-Ve´ıculos Ae´reos (MAVs) intensificou-se devido a`s suas car-
acter´ısticas e potencial gama de aplicac¸o˜es. Consequentemente, surgiu uma grande necessidade em
entenderecontrolaraaerodinaˆmicadebaixosnu´merosdeReynolds.
Foi aplicado num proto´tipo de MAV de asa fixa um me´todo passivo optimizado para o controlo
de escoamento e obtiveram-se ganhos a n´ıvel do desempenho aerodinaˆmico, o que provou que esta
seria uma boa soluc¸a˜o para controlar o escoamento no regime de baixo nu´mero de Reynolds. Con-
tudo, em condic¸o˜es de pre´-perda, detectou-se uma bolha de separac¸a˜o que deteriora a performance
aerodinaˆmica do MAV quando comparado com a situac¸a˜o em que nenhum me´todo de controlo e´ apli-
cado. Esta tese propo˜e-se a resolver este problema atrave´s da implementac¸a˜o de um sistema de
controlo activo que operara´ nas condic¸o˜es de pre´-perda. O me´todo escolhido foi injecc¸a˜o de ar que
deveriaseralimentadoatrave´sdoaproveitamentodaenergiadevibrac¸a˜odaestruturadaasaenquanto
esta´ avoar.
Para o projecto do colector de energia piezoele´ctrico desenvolveu-se um modelo electromecaˆnico
que simula a resposta destes dispositivos. Os efeitos do sistema de controlo de escoamento activo
na performance aerodinaˆmica do MAV foram obtidos atrave´s de ensaios em tu´nel de vento com uma
balanc¸aaerodinaˆmicaeome´tododePIV.
Osresultadosdemonstraramquecomosistemadecontrolodeescoamentoh´ıbrido(passivo-activo)
o desempenho aerodinaˆmico do MAV e´ melhorado, a perda e´ atrasada e a sustentac¸a˜o aumenta na
po´s-perdatambe´m. Portanto,agamadeoperac¸a˜odosMAVstempotencialparacrescer.
Palavras-chave:
MAV,AerodinaˆmicadeBaixoNu´merodeReynolds, SistemasdeControlo
de Escoamento Activo, Desempenho Aerodinaˆmico, Recolha de Energia, Colector Piezoele´ctrico, En-
saiosemTu´neldeVento,Me´tododePIV.
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Abstract
In the last years, Micro Aerial Vehicles (MAVs) have become very popular due to its characteristics
and its potential range of applications. Accordingly, there is an urge to understand and control low
Reynoldsnumberaerodynamics.
An optimized passive flow control method was applied to a fixed-wing MAV prototype and gains
in aerodynamic performance were obtained, thus demonstrating that it was a good solution to control
the flow in the regime of low Reynolds numbers. However, in pre-stall conditions, a separation bubble
was detected, leading to a worse aerodynamic performance of the MAV with the use of the passive
stall control system than if any flow control system was applied. This thesis proposes to solve this
issue through the application of an active flow control system to operate in pre-stall conditions. The
chosen active method was air injection that should be powered by vibrational energy harvested from
wingstructurewhileinoperation.
To design a piezoelectric energy harvester, an electromechanical model was designed that simu-
lated the response of such devices. The effects of the active flow control system on the aerodynamic
performanceoftheMAVwereassessedwithwindtunneltests,employinganaerodynamicbalanceand
aPIVmethod.
The results showed that with the use of the hybrid (passive-active) flow control system the aerody-
namic performance of the MAV is improved, the stall is delayed and the lift is enhanced in post-stall
conditionsaswell. Therefore,theoperationalrangeofMAVshasapotentialtogrow.
Keywords:
MAV, Low Reynolds Number Aerodynamics, Active Flow Control System, Aerodi-
namicPerformance,EnergyHarvesting,PiezoelectricHarvesterDevice,WindTunnelTests,PIVMethod.
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