Numerička simulacija dinamike mahokrila

master's thesis

• Title (english): Numerical simulation of flapping wing
• Author: Danijel Bosnar
• Mentor: Zdravko Terze (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

U ovom radu simulirana je dinamika mahokrila kroz tri slučaja 2D simulacije. U prva dva slučaja naglasak je na prikazivanju utjecaja vrtloga napadnog brida u stvaranju uzgona. U trećem slučaju ostvarena je sprega između programa specijaliziranog za računalnu dinamiku fluida, OpenFOAM i programa za analizu dinamike više tijela, MBDyn. Prvi slučaj simulira gibanje krila nalik na leptira vrste Janatella l. prema Suzuki et al. [2] za niske Re brojeve (100, 500 i 1000) te je rezultat ostvarivanje sile uzgona u zamahu krila prema dolje i sile propulzije u povratnom zamahu prema gore. Također utvrđen je porast sila uzgona i propulzije s porastom Re broja kao i smanjivanjem amplitude napadnog kuta dok se utjecaj debljine aeroprofila, za NACA0012 i NACA0006, nije pokazao značajnim. Iz autorove želje za pomicanje mreže u tim simulacijama korištena je klasa nastala modifikacijom displacementLaplacian klase u kojoj je ostvareno translacijsko pomicanje AMI granice unutar mreže s ciljem neograničene rotacije unutrašnje zone oko profila. U drugom slučaju simulira se gibanje krila vinske mušice Drosophila m. prema [3] uspoređujući dva tipa putanje gdje se putanja u obliku osmice pokazala boljom spram ovalne putanje ostvarujući veće sile. U trećem slučaju simulacija ostvarena je slaba sprega između programskih paketa otvorenog koda, OpenFOAM i MBDyn sa svrhom ostvarivanja FSI simulacije. Za primjer je napravljena simulacija aeroprofila u slobodnoj struji zraka vezanog torzijskom prednapregnutom oprugom. Komunikacija se odvija putem socket-a gdje je MBDyn server, a OpenFOAM klijent. Nedostatak sprege je neostvarena mogućnost komuniciranja u paralelnom računanju, zatim MBDyn koristi fiksni vremenski korak te MBDyn ne može ponovno započeti simulaciju od zadnjeg vremenskog koraka što poskupljuje računalnu simulaciju te su rješenja za to budući ciljevi za ovu spregu. Također je jedan od budućih ciljeva ostvariti spregu u kojoj se može simulirati elastično krilo.

Abstract (english)

In this thesis the dynamics of flapping flight is simulated through three cases of 2D simulations. In first two cases the main goal is to show the influence of LEV on the production of lift and propulsion forces. In the third case the coupling between Open-FOAM and MBDyn was achieved and demonstrated. In the first case of simulation the motion of butterfly Janatella l. was simulated according to Suzuki et al. [2] for the low Re numbers (100, 500 and 1000) and the result was achieving lift in the downward stroke and propulsion in the upward stroke. Also the lift and propulsion rise in amplitude as the Re rises and as the mean amplitude of the angle of attack is lower while the difference in thickness of aeroprofiles NACA0012 and NACA0006 was not of the significance. For the mesh movement author decided to modify displacementLaplacian motion solver in the way that it became possible to translationally move the AMI across the domain while the border of the domain don't move and the inner zone around the wing profile can rotate without influencing the deformation of the mesh. Second case of simulations showed the motion of the fruit fly Drosophila m. according to [3] comparing two paths of the wing where the eight like pattern path showed better then the oval path because of achieving greater lift and propulsion. In the third case of simulations the weak coupling between OpenFOAM and MBDyn is accomplished with the goal of FSI simulation. One demonstrative FSI case was made where the aeroprofile is in the air freestream while being constrained with torsional prestrained spring. The communication between OF and MBDyn is via socket communication where MBDyn acts as server and OpenFOAM as client. The cons of coupling is the impossibility of running in parallel, MBDyn uses only fixed timestep and MBDyn can't restart simulation from the last time step which all in all makes the simulations expensive and solutions for that are the next goals for this coupling. Also one of the goals which is to achieve is the FSI simulation with flexible wing.

• Keywords: RDF; slaba sprega; FSI; vrtlog napadnog brida; LEV; mahokrilac; MBDyn; OpenFOAM
• Keywords (english): CFD; weak coupling; FSI; LEV; flapping flight; MBDyn; OpenFOAM
• Language: croatian
• URN:NBN: urn:nbn:hr:235:982247
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 22:39:19