Numerical Aerodynamic Characteristics Estimation of Airfoil in Transonic and Supersonic Air Flow

Cilj ovog diplomskog rada je bio provesti numerički proračun aerodinamičkih karakteristika aeroprofila u krozzvučnoj i nadzvučnoj struji zraka. Proračun je napravljen pomoću računalne dinamike fluida (CFD-Computational Fluid Dynamics) unutar ANSYS Fluent Student Software-a koji koristi matematičke odnose i algoritme, dobivene rješavanjem kompletnih Navier-Stokes-ovih jednadžbi, za analizu i dobivanje rezultata, kao što su koeficijenti uzgona i otpora, te sile uzgona i otpora koje određuju mogućnosti aeroprofila. U ovom radu je provedena CFD analiza na nadzvučnom „dijamantnom“ dvostruko simetričnom klinastom aeroprofilu oko kojeg je modelirano krozzvučno i nadzvučno strujanje uz promjenu napadnog kuta. Promatrana strujanja su stlačiva i turbulentna, te se koristi DB rješavač (density-based solver), koji daje dobre rezultate za stlačiva strujanja krozzvučnih i nadzvučnih brzina. Koeficijenti uzgona i otpora za krozzvučno strujanje nisu konvergirali prema konačnoj stalnoj vrijednosti, te se pri visoko podzvučnoj (krozzvučnoj) brzini ne mogu uzeti s pouzdanošću u njihovu točnost, ali pri krozzvučnoj brzini niske nadzvučne vrijednosti, koeficijenti su, iako bez potpune konvergencije, poprimili konačnu vrijednost te se mogu uzeti s pouzdanošću u njihovu točnost. Koeficijenti uzgona i otpora za nadzvučno strujanje, dobiveni numeričkim pristupom, uspoređeni su s teorijskim rezultatima, za koje je proveden egzaktni proračun u ovom radu, te je postignuto gotovo savršeno podudaranje.Objective of this master thesis was to conduct numerical aerodynamic characteristics estimation of airfoil in transonic and supersonic air flow. Estimation was made using Computational Fluid Dynamics (CFD) within ANSYS Fluent Student Software which incorporates mathematical relations and algorithms, obtained by solving complete Navier-stokes equations, to analyze and obtain results, such as lift and drag coefficients, and lift and drag forces which determine airfoil capabilities. In this paper, CFD analysis was conducted on supersonic diamond double symmetrical wedge shaped airfoil, over which a transonic and supersonic flow was modelled, with change of angle of attack. Observed flows are compressible and turbulent and density-based solver is used, which gives good results for transonic and supersonic compressible flows. Lift and drag coefficients for transonic flow didn´t converge towards finite constant value, and at high subconic (transonic) speed they can´t be taken with confidence in their accuracy, but at transonic speed of low supersonic value, coefficients have, although without complete convergence, obtained finite value and can be taken with confidence in their accuracy. Lift and drag coefficients for supersonic flow, obtained with numerical approach, are compared with theoretical results, for which exact estimation was made, and almost perfect agreement was achieved