The influence of fuel properties on spray characteristics

Ob vse večji energetski krizi ter neizogibnem dejstvu, da bo človeštvo slej ko prej porabilo zalogo nafte, se pojavlja vprašanje, kaj bo nadomestilo fosilna goriva. Biogoriva so eden izmed trenutno najpogostejših odgovorov na zastavljeno vprašanje. Namen tega dela je bilo pridobiti podatke o vplivu lastnosti biodizelskega goriva na tok v visokotlačni šobi ter na curek, ki se razvije ob vbrizgavanju v zgorevalni prostor motorja. Te podatke smo pridobili na podlagi numerične analize, ki smo jo izvedli v programskem okolju AVL FIRE. Te podatke smo primerjali s podatki enake analize, ki smo jo izvedli za klasično dizelsko gorivo. Opazili smo, da se višja dinamična viskoznost, gostota ter površinska napetost biogoriva odražajo na večji dolžini ter ožji širini curka goriva. Iz rezultatov je razvidno tudi, da uporaba biodizla privede do manjših kapljic goriva ter počasnejšega razvoja kavitacije v toku skozi izvrtino šobe.Due to ever growing energy crisis, and the inevitable fact that human kind wil use all of the Earths oil sooner or later. The question occurs. What will replace the fossil fuels? -Biofuels, is among the most popular aswers. The purpose of this work is to gather information on how the biofuels\u27s chracteristics, influence the flow inside the highpressure injector, and on the spray characterics of fuel injected into diesel engine. The data was gathered based on numerical simulation which was preformed with AVL FIRE program. Same simulation was also preformed for conventional diesel fuel. The results have shown that biodiesel\u27s higher dynamic viscosity, higher density and higher surface tension, reflect in a longer and narrower jet of fuel. Narrower angle of spray and smaller droplet diameter. And slower cavitation development inside the nozzle flow