Numerical modelling of spray and combustion processes using the Euler Eulerian multiphase approach

doctoral thesis

• Title (croatian): Numeričko modeliranje procesa spreja i izgaranja korištenjem Euler Eulerovog višefaznog pristupa
• Author: Zvonimir Petranović
• Mentor: Milan Vujanović (mentor)
• Committee member: Neven Duić (predsjednik povjerenstva)
• Committee member: Milan Vujanović (član povjerenstva)
• Committee member: Darko Kozarac (član povjerenstva)
• Committee member: Wilfried Edelbauer https://orcid.org/0000-0002-2905-4542 (član povjerenstva)
• Committee member: Peter Priesching (član povjerenstva); strani drzavljanin: Nije dostupno
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2016-12-05, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Process Energy Engineering
• Universal decimal classification (UDC): 51 - Mathematics

Abstract

The goal of this thesis is to develop advanced engineering method for numerical modelling of highly turbulent multiphase combustion processes. The first objective was to use the commercial 3D Computational Fluid Dynamics (CFD) code FIRE® and model real engineering system by changing various combustion parameters. In this section, the spray process was modelled by employing the widely used Euler Lagrangian discrete Droplet Method (DDM). The focus was to gain insight into advantages and disadvantages of that approach. In the second section, the Euler Eulerian multiphase approach sub – models, namely the liquid jet primary atomization and droplet secondary atomization model were thoroughly analysed and parametrized. Furthermore, the primary atomization model was validated against Direct Numerical Simulation (DNS) data, a new inlet boundary condition was developed, and the nozzle flow – spray interface was enhanced within the Euler Eulerian spray module. In the third section, the validation and enhancement of the WAVE secondary break – up model within the Euler Eulerian framework was performed. The modelled spray cloud shape, spray cone angle, liquid penetration, and droplet size distributions were compared to the available experimental data. In the fourth section, the stochastic O’Rourke collision model was modified and implemented into the Euler Eulerian spray code. In the fifth section, the multiphase module was enhanced with the combustion model where the combustion process was described through general gas phase reactions and chemistry mechanisms. The developed method was verified by numerical modelling of constant volume reactor filled with liquid – gas mixture under elevated pressure and temperature conditions. In the last section, the newly developed method was extensively validated by comparing the simulation results to the available experimental data from the Engine Combustion Network (ECN) database. The liquid and vapour phase penetration, mixture distribution, spray cloud shape and temperature field were examined for various combustion parameters. To find the most suitable spray sub – model coefficients, a high pressure liquid fuel injection into the non – reactive environment was modelled. Finally, the developed method was used to model internal combustion engine compression and expansion stroke. The given results imply that the developed method can be reliably used in a modern engineering development processes.

Abstract (croatian)

Cilj ovog rada je razviti naprednu inženjersku metodu za računalno modeliranje turbulentnih višefaznih strujanja i procesa izgaranja. U prvom dijelu teze modelirani su realni inženjerski sustavi uz varijacije parametara izgaranja. U ovom dijelu teze, za opisivanje procesa spreja korišten je Euler Lagrangeov pristup izoliranih čestica (DDM). Navedeni model spreja korišten je s ciljem stjecanja razumijevanja njegovih prednosti i nedostataka. U drugom dijelu teze provedena je parametrizacija postojećih modela primarnog raspada mlaza goriva i sekundarnog raspada kapljica korištenjem Euler Eulerovog višefaznog pristupa. Modeli su parametrizirani računalnim modeliranjem ubrizgavanja goriva u nereaktivnu okolinu s povišenom temperaturom. Nadalje, primarni model raspadanja mlaza goriva validiran je usporedbom s rezultatima izravnih numeričkih simulacija (DNS), razvijen je novi rubni uvjet za ubrizgavanje goriva i unaprijeđeno je postojeće sučelje sapnica – sprej unutar Euler Eulerovog modela spreja. U trećem dijelu teze verificiran je, validiran i modificiran WAVE model sekundarnog raspada kapljica unutar Euler Eulerovog pristupa. Izračunati oblik isparenog goriva, kut spreja, penetracija goriva te distribucija kapljica uspoređeni su s dostupnim eksperimentalnim podacima. U četvrtom dijelu teze modificiran je i unaprijeđen O'Rourke model sudaranja kapljica unutar Euler Eulerovog sprej modela. U petom dijelu teze Euler Eulerov model nadograđen je s modelom za opisivanja procesa izgaranja. Verifikacija razvijene metode izvršena je računalnim modeliranjem reaktora s konstantnim volumenom ispunjenog smjesom goriva i plinova u uvjetima povišenog tlaka i temperature. U šestom dijelu teze novo razvijena metoda validirana je usporedbom modeliranih rezultata s eksperimentalnim podacima grupe koja se bavi istraživanjem procesa izgaranja u motorima s unutarnjim izgaranjem (eng. Engine Combustion Network – ECN). Uspoređeni su podaci penetracije kapljevite i plinovite faze, radijalna i aksijalna distribucija isparenog goriva, oblik isparenog goriva te temperaturna polja. Kako bi se definirali odgovarajući koeficijenti korištenih modela spreja, provedeno je istraživanje ubrizgavanja kapljevitog goriva u nereaktivnu okolinu. Nakon toga, izvršena je validacija razvijene metode računalnim modeliranjem realnih sustava ubrizgavanja. U završnom dijelu rada, novo razvijena metoda korištena je za računalne simulacije motora s unutarnjim izgaranjem.

• Keywords: computational fluid dynamics; numerical modelling; Euler Eulerian approach; Euler Lagrangian approach; multiphase; spray process; primary break – up; secondary break – up; droplet collision; droplet evaporation; vapour combustion; compression ignition; IC engine; diesel; n – heptane; n – dodecane; reaction kinetics; constant volume vessel; pollutant emission
• Keywords (croatian): računalna mehanika fluida; modeliranje; Euler Eulerov pristup; Euler Lagrangeov pristup; višefazno strujanje; proces spreja; primarno raspadanje mlaza goriva; sekundarno raspadanje kapljica goriva; sudaranje kapljica; isparavanje; izgaranje; samozapaljenje; motor s unutarnjim izgaranjem; dizel; n – heptane; n – dodecane; kemijska kinetika; komora s konstantnim volumenom; štetne emisije
• Language: english
• URN:NBN: urn:nbn:hr:235:810384
• Study programme: Title: Mechanical Engineering and Naval Architecture; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje tehničkih znanosti (doktor/doktorica znanosti, područje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-04-15 16:39:45