TESTING OF THE APPLICABILITY OF MATHEMATICAL MODELS OF LOWER LEVEL APPROXIMATION OF NAVIER-STOKES EQUATIONS ON THE FLOW AROUND AEROPROFILES USING CFD ANALYSIS

U ovome radu opisani su opći zakoni aerodinamike za primjenu strujanja zraka oko aeroprofila. Na osnovi primjenjivosti matematičkih modela niže razine aproksimacija Navier-Stokesovih jednadžbi izrađeni su CFD modeli raznih vrsta optjecanja oko aeroprofila. Prikazana je dimenzija aeroprofila, važne dimenzijske karakteristike, koje čine svaki aeroprofil posebnim. Utjecaj karakteristika zraka (gustoća, viskoznost, stlačivost) na strujanje je također objašnjeno u ovome radu. Sve je navedeno uvršteno u Navier-Stokesove jednadžbe koje su modificirane prema vrsti strujanja. Objašnjena je razlika između potencijalnog, laminarnog i turbulentnog strujanja. Ispitan je utjecaj Reynoldsovog broja na strujanje. Bitna je pozadina, odnosno objašnjenje svega što je prethodno navedeno kako bi rezultati CFD riješenja imali smisla i kako bi se to kasnije u analizi moglo usporediti sa stvarnim procesom. U protivnom, ne razumijevanjem osnovnih dijelova za primjenu CFD riješavača rezultati neće imati smisla i dobiti će se kriva predodžba. Na osnovi izrađena tri različita modela za svako strujanje, provedena je detaljna analiza. Za svaki aeroprofil (NACA 0012, NACA 4418, NACA 4421) posebno je ispitano pri kojem Reynoldsovom broju dolazi do promjene vrste strujanja, gdje se pojavljuje koje strujanje, te kako utječe oblik aeroprofila na to strujanje.This paper describes the general laws of aerodynamics for the application of air flow around an airfoil. Based on the explained applicability of mathematical models of lower level approximations of Navier-Stokes equations, CFD models of various types of flow around airfoils were developed. The dimension of the airfoil is presented as are important dimensional characteristics which make each airfoil special. The influence of air characteristics (density,viscosity, compressibility) on the flow is also explained in this work. All of the explained parameters are included in the Navier-Stokes equations that are modified according to the type of flow. The difference between potential, laminar and turbulent flow is also explained. Influence of Reynolds number on the flow is investigated. The background is important, such as the explanation of everything that was previously stated, how the results of the CFD solution made sense and how they could be compared with the actual processes later in the analysis. Otherwise, not understanding the basic parts for applying a CFD solver the results won’t make sense and we can get someone’s misconceptions. Based on the three different models developed for each flow, a detailed analysis will be required. Within the analysis, it is important to compare for each airfoil (NACA 0012, NACA 4418, NACA 4421) separately, at which Reynolds number there are changes in flow patterns, where which flows occur, and how the shape of the airfoil affects the flow