Marine propeller hydrodynamic characteristics evaluation using an open-source solver

Glavna svrha ovoga zadatka bila je pokazati koliko je odstupanje hidrodinamičkih karakteristika propelera dobivenih pomoću CFD alata i dva komercijalna CFD rješavača u odnosu na eksperimentalno dobivene rezultate. CFD alati i rješavači koriste se pri rješavanju problema koji se pojavljuju u području dinamike fluida. Prvi korak je napraviti diskretizaciju geometrije propelera mrežom konačnih volumena. Što je kvaliteta mreže bolja to će rezultati biti precizniji. Kvaliteta mreže ovisi o dosta čimbenika, o čemu će biti riječi nešto kasnije. Postoji velik broj CFD alata, a za naš slučaj koristili smo program Numeca. Nakon što je izrađena mreža ona se ubacuje u jedan od CFD rješavača. U njima se postavljaju uvjeti simulacije i radi numerička analiza protoka fluida. Time je omogućen uvid u različite karakteristike samog fluida, kao što su tlak i brzina, ali i uvid u same karakteristike zadane geometrije. Za naš slučaj koristili smo rješavač otvorenog koda OpenFOAM, te Fluent iz programskog paketa Ansys. Oba rješavača vrlo dobro aproksimiraju stvarne rezultate te se vrlo često koriste kod rješavanja problema u ovoj grani mehanike fluida. Osim navedenoga rad sadrži i teorijski dio koji se osvćre na opis i podjelu propelera (brodskog vijka), kao i na objašnjenje pojma CFD-a.The main purpose of this task was to show how big is deviation of hydrodynamic characteristics of propeller obtained using CFD tools and two commercial CFD solvers in regards to results obtained with experimental measuring. CFD tools and solvers are used to solve problems which show up in the field of fluid dynamics. The first step is to make discretization of geometry with finite volume mesh. The better quality of the mesh is, the more accurate results will be. The mesh quality depends on many factors, which will be discussed later. There are a large number of CFD tools, and for our case we used a program Numeca. When making of the mesh is done, we put it in in one of CFD solvers. In solvers, setting of simulation conditions and doing numerical analysis of fluid flow is done. This enables an insight into the different characteristics of the fluid, such as pressure and speed, but also insight into the very characteristics of the given geometry. For our case we used open-source solver OpenFOAM and Fluent from Ansys software package. Both solvers very well approximate the actual results and are often used in solving problems in this branch of fluid mechanics. In addition to above, this work contains theoretical part which refers to the description and division of propeller, as well as the explanation of CFD