Numerical analysis of the engine with spark ignition and compression ignition

U radu se prikazuju istraživanja simulacije izgaranja u testiranom motoru s četiri cilindra, na osnovu motora Toyote Yaris 1,3 dm3 s paljenjem iskrom i opremljenim s dva sustava napajanja energijom: osnovnim i paljenjem. Primijenjene su dvije metode pokretanja postupka izgaranja: paljenje iskrom i ponovo, poslije isključenja, ubrizgavanje zapaljive doze. Cilj je istraživanja bilo utvrđivanje razlika u postupku izgaranja i radu motora, prije svega promjena tlaka do kojih je došlo u cilindru te vrste motora s dva sustava napajanja energijom. Zapaljiva doza uštrcana u cilindar bila je jednaka otprilike 5 ÷ 8 % ukupne mase goriva u motoru. Gorivo je direktno ubrizgavano tijekom nekoliko desetaka stupnjeva rotacije koljenaste osovine prije dostizanja gornje mrtve točke. Pripremljena je prostorna mreža modela motora (predprocesor), a napravljena je i modifikacija izvornog KIVA 3V programa kako bi se uzela u obzir dva sustava ubrizgavanja. Treba spomenuti da standardni KIVA 3V program ima, po defaultu, samo jedan izvor ubrizgavanja goriva.The article presents simulation researches on the combustion process in the four-cylinder testing engine, based on the spark ignition engine Toyota Yaris 1,3 dm3 which was equipped with two systems of power supply i.e.: fundamental and ignition. Two methods of initiating the combustion process were applied: by spark ignition and, after it was turned off, by means of the ignition dose injection. The researches aimed at revealing the differences in the combustion process and engine performance, above all the changes in pressure that occurred in the cylinder for that kind of two-fuel power supply of the engine. The ignition dose injected into the cylinder was equal to about 5 ÷ 8 % of the general mass of the fuel supplied to the engine. The mass of the fuel injected into the approach collector determined the remaining part, and the direct injection of the fuel took place over several dozen of rotation degrees of the crankshaft before TDC (Top Dead Centre). A spatial grid of the engine’s model (pre-processor) was prepared, and also a modification to the source KIVA 3V program was made consisting in taking into account of two systems of injection. It is necessary to mention that the standard KIVA 3V program contains, as a default, only one source of fuel injection

Modelling of the injection and combustion processes in the gasoline direct injection engine

Rad prikazuje modeliranje procesa ubrizgavanja pomoću KIVA programa. Složeni matematički modeli koji se koriste u izračunima i koji opisuju procese koji se odvijaju unutar cilindra motora omogućuju generiranje kompliciranih virtualnih modela koji odražavaju stvarne uvjete na zadovoljavajući način. Točnost rezultata proračuna određena je kvalitetom ulaznih podataka, koji se mogu dobiti na temelju ispitivanja s modelom. Na temelju modeliranja procesa ubrizgavanja i izgaranja u GDI motoru, predstavljenih u radu, dobivena je osnova za širu analizu plinsko-dinamičkih pojava.The paper presents modelling of the injection process by means of KIVA program. The elaborate mathematical models used in calculations describing the processes occurring inside the engine cylinder make it possible to create complicated virtual models reflecting real conditions in a satisfactory way. The accuracy of calculation results is determined by the quality of input data, which can be obtained based on model investigations. Based on the modeling of injection and combustion processes in the GDI engine, presented in the work, the basis for a broader analysis of the gas-dynamic phenomena was obtained