BIODIESEL AND WASTE COOKING OIL AS THE ALTERNATIVE FUELS: THE INJECTION PROCESS ASPECT

Sažetak U ovom radu će se raspraviti utjecaj uporabe alternativnih goriva na proces ubrizgavanja, karakteristika strujanja u mlaznicama i proces tvorbe mlaza. Rezultati analize dobiveni su na osnovi analiza uz uporabu paketa računske dinamike fluida FIRE, jednodimenzionalnog modela za izračun karakteristika ubrizgavanja i empirijskih izraza za izračun dimenzija kapljica ubrizganog goriva te dometa mlaza. Kalkulacije su izrađene za konvecionalan sustav ubrizgavanja s linijskom pumpom, visokotlačnim cijevima i mlaznicom sa četiri rupe. Dobiveni rezultati mogu se koristiti za ispravno podešavanje sustava za ubrizgavanje na primjeru uporabe alternativnog goriva umjesto klasičnog dizelskog goriva.Abstract The presented paper discusses the influence of using alternative fuels on the fuel injection process, in-nozzle flow characteristics and spray formation process. The analysis is performed using the computational fluid dynamics package Fire, a one-dimensional mathematical model for the injection process characteristics calculations and empirical models for calculating the injected droplet mean diameter and spray penetration length. The calculations were performed for the conventional fuel injection system with the in-line pump, high pressure tube and four-hole nozzle with the sac chamber. The results of presented analysis can be used to set properly the fuel injection system for operation with alternative fuels

BIODIESEL AND WASTE COOKING OIL AS THE ALTERNATIVE FUELS: THE INJECTION PROCESS ASPECT

Sažetak U ovom radu će se raspraviti utjecaj uporabe alternativnih goriva na proces ubrizgavanja, karakteristika strujanja u mlaznicama i proces tvorbe mlaza. Rezultati analize dobiveni su na osnovi analiza uz uporabu paketa računske dinamike fluida FIRE, jednodimenzionalnog modela za izračun karakteristika ubrizgavanja i empirijskih izraza za izračun dimenzija kapljica ubrizganog goriva te dometa mlaza. Kalkulacije su izrađene za konvecionalan sustav ubrizgavanja s linijskom pumpom, visokotlačnim cijevima i mlaznicom sa četiri rupe. Dobiveni rezultati mogu se koristiti za ispravno podešavanje sustava za ubrizgavanje na primjeru uporabe alternativnog goriva umjesto klasičnog dizelskog goriva.Abstract The presented paper discusses the influence of using alternative fuels on the fuel injection process, in-nozzle flow characteristics and spray formation process. The analysis is performed using the computational fluid dynamics package Fire, a one-dimensional mathematical model for the injection process characteristics calculations and empirical models for calculating the injected droplet mean diameter and spray penetration length. The calculations were performed for the conventional fuel injection system with the in-line pump, high pressure tube and four-hole nozzle with the sac chamber. The results of presented analysis can be used to set properly the fuel injection system for operation with alternative fuels

A spray analysis of petrol and alternative fuels

V prispevku je obravnavana numerična analiza curkov plinskega olja in nekaterih nadomestnih goriv. Z uporabo paketa računske dinamike tekočin FIRE so bile določene karakteristike curkov (velikost kapljic in domet) plinskega olja, biodizla in odpadnega rastlinskega olja. Nekatere vrednosti karakterističnih veličin curka so bile primerjane tudi z vrednostmi, izračunanimi z uporabo znanih empiričnih modelov za določitev karakteristik curka. Analize so bile izvedene za dva tipa vbrizgalnih šob oz. vbrizgalnih sistemov (neposredni in posredni). V primeru slednjega so rezultati numerične analize primerjani še s fotografijami curka.This paper presents numerical analyses of sprays of diesel and some alternative fuels. The fuel spray characteristics (the droplet size and the penetration length) of diesel fuel, biodiesel and waste cooking oil were calculated using the computational fluid dynamics program FIRE. Some of the characteristics were calculated using existing empirical models. The analyses were made for two different injection systems: direct and indirect injection. In the case of indirect injection, the results were also compared with fuel-spray photographs

Diesel-spray analysis

V prispevku je obravnavan proces vbrizgavanja goriva in karakteristike curka dizelskega motorja z uporabo programa računske dinamike tekočin FIRE. Natančnost rezultatov, dobljenih s tem programom, je v veliki meri odvisna od pravilno postavljenih začetnih pogojev. Določevanje nekaterih pogojev je precej zahtevno, saj jih lahko določimo le na temelju izkušenj ali zahtevanih meritev v laboratoriju. V tem prispevku so na podlagi številnih zgledov in primerjav z rezultati, dobljenimi z znanimi empiričnimi izrazi za srednji Sauterjev premer kapljic, podane smernice za postavljanje začetnih pogojev.The fuel injection process and the characteristics of the diesel-fuel spray were simulated using a computational fluid dynamics program FIRE. Initial conditions greatly influenced the accuracy of te results and these conditions can generally only be determined by complicated laboratory measurements. Guidelines to determine more realistic initial conditions based on comparisons of different practical results and empirical expressions for Sauter\u27s mean diameter of a droplet are given in the paper

Coupled simulations of nozzle flow, primary fuel jet breakup, and spray formation

Presented are two approaches for coupled simulations of the injector flow withspray formation. In the first approach the two-fluid model is used within the injector for the cavitating flow. A primary breakup model is then applied at the nozzle orifice where it is coupled with the standard discrete droplet model. In the second approach the Eulerian multi-fluid model is applied for both the nozzle and spray regions. The developed primary breakup model, used in both approaches, is based on locally resolved properties of the cavitating nozzle flow across the orifice cross section. The model provides the initial droplet size and velocity distribution for the droplet parcels released from the surface of a coherent liquid core. The major feature of the predictions obtained with the model is a remarkable asymmetry of the spray. This asymmetryis in agreement with the recent observations at Chalmers University where they performed experiments using a transparent model scaled-up injector.The described model has been implemented into AVL FIRE computational fluid dynamics code which was used to obtain all the presented results