Boundary layer method for unsteady aerodynamic loads determination

doctoral thesis

• Title (croatian): Metoda graničnog sloja za određivanje nestacionarnih aerodinamičkih opterećenja
• Author: Frane Majić
• Mentor: Zdravko Virag (mentor)
• Mentor: Ralph Voss (komentor); VIAF: 236683450
• Committee member: Zdravko Terze (predsjednik povjerenstva)
• Committee member: Zdravko Virag (član povjerenstva)
• Committee member: Ralph Voss (član povjerenstva); VIAF: 236683450
• Committee member: Zoran Milas (član povjerenstva)
• Committee member: Milan Vrdoljak (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2010-05-25, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Aviation, Rocket and Space Technology; Aircraft Construction and Design
• Universal decimal classification (UDC): 53 - Physics

Abstract

In this work a simple and accurate method for two-dimensional unsteady aerodynamic load determination on airfoil is developed. The method employs viscous-inviscid coupling. The inviscid flow is governed by the unsteady Euler equations solved by finite volume method on moving C-type rigid grid, while viscous flow is governed by steady boundary layer integral equations. The Euler equations are solved in conservative form, in transformed body-fitted coordinates. The viscous-inviscid coupling is... More performed by transpiration velocity incorporated in the boundary condition on airfoil. Therefore, the method requires no grid deformation for the boundary layer influence inclusion. The transition is predicted by the en method. The viscous-inviscid method is focused on subsonic and transonic flows, at high Reynolds number, with shock-wave appearance. The steady and unsteady test cases for three characteristic airfoils are performed, namely NACA 0012, NACA64A010, NLR 7301. The results are compared with experimental data and with unsteady RANS calculations. The method gives results which are in good agreement with experimental data and with calculated unsteady RANS results. The method has convergence problems in the test cases with separation. The method is applicable in the design processes where unsteady loads are required within reasonable time and with accuracy comparable with RANS methods. Less

Abstract (croatian)

U ovome radu razvijena je jednostavna i precizna metoda za odredivanje nestacionarnih aerodinamičkih optrećenja za dvodimenzionalno strujanje oko aeroprofila. Metoda koristi princip sprezanja viskoznog i neviskoznog dijela strujanja. Neviskozni dio strujanja je opisano nestacionarnim Eulerovim jednadžbama koje su riješene pomoću metode kontrolnih volumena na pomičnoj nedeformabilnoj mreži C-tipa. Viskozni dio strujanja je opisan integralnim jednadžbama graničnog sloja za stacionarno... More strujanje koje su riješene Runge-Kutta metodom četvrtog reda. Eulerove jednadžbe su riješene u konzervativnom obliku, u transformiranim prianjajućim koordinatama. Sprezanje viskoznog i neviskoznog dijela strujanja je izvedeno pomoću transpiracijske brzine koja je uključena u rubni uvjet na aeroprofilu. Iz tog razloga metoda ne zahtijeva deformaciju mreže da bi se uključio utjecaj graničnog sloja. Položaj tranzicije graničnog sloja je predviđen pomoću en metode. Metoda viskozno-neviskoznog sprezanja je usmjerena na podzvučno i kroz zvučno strujanje pri velikim Reynoldsovim brojevima, s pojavom udarnog vala. Izvršeni su proračuni za stacionarno i nestacionarno strujanje, za tri karakteristična aeroprofila NACA 0012, NACA64A010 i NLR 7301. Rezultati su usporedeni s eksperimentalnim podacima i s nestacionarnim RA\NS proračunima. Metoda daje rezultate koji se dobro slažu s eksperimentalnim podacima i s proračunatim nestacionarnim RANS rezultatima. U slučajevima strujanja s odvajanjem, metoda pokazuje probleme s konvergencijom. Metoda je primjenjiva u procesima razvoja gdje se zahtijeva proračun nestacionarnih opterećenja unutar prihvatljivog vremena računanja i s preciznošću koja je usporediva s RANS metodama. Less

• Keywords: viscous-inviscid coupling; viscous flow; Euler equations; transpiration velocity; computational fluid dynamics; mach number; airfoil; shock-wave; airfoil pressure coefficient distribution
• Keywords (croatian): viskozno-neviskozno sprezanje; viskozno strujanje; Eulerove jednadžbe; transpiracijska brzina; računalna dinamika fluida; Machov broj; aeroprofil; udarni val; raspodjela koeficijenta tlaka na aeroprofilu
• Language: english
• URN:NBN: urn:nbn:hr:235:562514
• Promotion: 2020
• Study programme: Title: Mechanical Engineering and Naval Architecture; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje tehničkih znanosti (doktor/doktorica znanosti, područje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-06-25 11:17:35