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undergraduate thesis
Utjecaj oblika prostora izgaranja na performanse Ottovog motora
Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2017. urn:nbn:hr:235:115974
Kaurić, Mario
University of Zagreb
Faculty of Mechanical Engineering and Naval Architecture

Institutional repository: Repository of Faculty of Mechanical Engineering and Naval Architecture University of Zagreb

Cite this document

Kaurić, M. (2017). Utjecaj oblika prostora izgaranja na performanse Ottovog motora (Undergraduate thesis). Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture. Retrieved from https://urn.nsk.hr/urn:nbn:hr:235:115974

Kaurić, Mario. "Utjecaj oblika prostora izgaranja na performanse Ottovog motora." Undergraduate thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2017. https://urn.nsk.hr/urn:nbn:hr:235:115974

Kaurić, Mario. "Utjecaj oblika prostora izgaranja na performanse Ottovog motora." Undergraduate thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, 2017. https://urn.nsk.hr/urn:nbn:hr:235:115974

Kaurić, M. (2017). 'Utjecaj oblika prostora izgaranja na performanse Ottovog motora', Undergraduate thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, accessed 02 June 2024, https://urn.nsk.hr/urn:nbn:hr:235:115974

Kaurić M. Utjecaj oblika prostora izgaranja na performanse Ottovog motora [Undergraduate thesis]. Zagreb: University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture; 2017 [cited 2024 June 02] Available at: https://urn.nsk.hr/urn:nbn:hr:235:115974

M. Kaurić, "Utjecaj oblika prostora izgaranja na performanse Ottovog motora", Undergraduate thesis, University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Zagreb, 2017. Available at: https://urn.nsk.hr/urn:nbn:hr:235:115974

Metadata
TitleUtjecaj oblika prostora izgaranja na performanse Ottovog motora
Title (english)Influence of the combustion chamber geometry on the performance of spark ignition engine
AuthorMario Kaurić
MentorMomir Sjerić (mentor)
GranterUniversity of Zagreb
Faculty of Mechanical Engineering and Naval Architecture
Zagreb
Defense date and country2017-03-02, Croatia
Scientific / art field,
discipline and subdiscipline		TECHNICAL SCIENCES
Mechanical Engineering
Abstract
Motori s unutarnjim izgaranjem su pogonski strojevi većine cestovnih vozila koji prometuju današnjim cestama. Elektromotor daje vučnu karakteristiku vrlo sličnu idealnoj hiperboli, no baterijski sustav nije dovoljno razvijen kako bi spomenuta kombinacija postala ozbiljan konkurent motoru s unutarnjim izgaranjem kao pouzdan i dugotrajan pogonski stroj. Razvoj modernih motora usmjeren je na poboljšanje performansi uz smanjenje potrošnje i zadovoljavanje sve rigoroznijih zakona o emisiji štetnih plinova u okoliš. Eksperimentalna istraživanja u području motora s unutarnjim izgaranjem zahtijevaju primjenu izrazito skupe opreme te znatno više vremena u usporedbi s primjenom numeričkih simulacija. Povećanjem mogućnosti računala računalne simulacije se promiču u glavni inženjerski alat za razvoj motora s unutarnjim izgaranjem. Izgaranje u Ottovom motoru započinje pojavom električne iskre između elektroda svjećice čime se električna energija impulsa pretvara u povećanje unutarnje energije što dovodi do inicijalnog zapaljenja smjese goriva i zraka. Nakon početne faze stvaranja jezgre plamena dolazi do širenja fronte plamena kroz cjelokupni prostor izgaranja što je popraćeno turbulentnim izgaranjem u cilindru. Najveći utjecaj na brzinu oslobađanja topline u Ottovom motoru, koja posljedično utječe na performanse motora, imaju turbulentno strujanje u cilindru i geometrija prostora izgaranja. Simulacijama radnog ciklusa (engl. Cycle-simulation) te primjenom tzv. kvazi-dimenzijskih modela izgaranja moguće je obuhvatiti utjecaj karakterističnih turbulentnih veličina i oblika prostora izgaranja na širenje fronte plamena tijekom izgaranja. Fraktalni model izgaranja, kao jedan od često korištenih kvazi-dimenzijskih modela izgaranja za Ottove motore, promatra izgaranje kao proces koji se sastoji od tri karakteristične faze: stvaranja jezgra plamena, turbulentnog izgaranja i dogorijevanje uz stjenku. U svrhu proračuna karakterističnih turbulentnih veličina kao što su intenzitet turbulencije i integralna duljina vrtloga potrebno je primijeniti pod-model turbulencije. U ovom radu korišten je K-k pod-model turbulencije. Za potrebe kalibracije konstantni simulacijskog modela izrađenog u komercijalnom programskom paketu AVL Boost izmjereni su eksperimentalni podatci za nekoliko radnih točaka eksperimentalnog motora Hatz 1D81 u Laboratoriju za motore i vozila.. Nakon provedene validacije i kalibracije konstanti simulacijskog modela provedene su numeričke analize utjecaja raznih oblika čela klipa i glave motora na srednji indicirani tlak i efektivnu snagu motora. Tijekom simulacija sve ostale geometrijske značajke motora i konstante pojedinih pod-modela ostale su nepromijenjene čime je osigurano izdvajanje utjecaja geometrije prostora izgaranja na performanse motora. Na kraju su prikazani, uspoređeni i objašnjeni simulacijski rezultati te su izvedeni zaključci o mogućnostima simulacija radnog ciklusa u pogledu analize utjecaja promjene geometrije prostora izgaranja na performanse Ottovog motora. Također, dane su smjernice za razvoj poboljšanog prostora izgaranja analiziranog motora.
Abstract (english)
Internal combustion engine propels most of vehicles that drive on traffic roads of today. Electric motor has traction characteristics very similar to ideal but battery system is not developed enough to become serious competition to internal combustion engine as reliable and long-lasting mover. The development of modern engines is aimed at improving performance while reducing consumption and meeting the rigorous laws on emissions into the environment. Experimental studies in the field of internal combustion engines require the use of extremely expensive equipment and much more time compared with the use of numerical simulation. By increasing the capabilities of computers numerical simulations became the main engineering tool for the development of the internal combustion engine. Combustion in the SI engine is initiated with electric spark discharge that occurs between the spark plug electrodes. Electrical energy is transformed into internal energy which results with ignition of the fuel-air mixture. After early flame kernel formation and growth flame is fully developed and turbulent combustion in the cylinder starts. Turbulent flow in the cylinder and combustion chamber geometry have the biggest influence on the rate of heat release (ROHR) in the SI engine, which has an impact on engine performance. Cycle-simulation with the application of the so-called quasi-dimensional combustion model can include the impact of turbulence and shape of the combustion chamber on the expansion of the flame front during combustion. In fractal combustion model, one of the frequently used quasi-dimensional combustion model for the SI engine, combustion process consists of three distinctive phases: flame kernel growth, turbulent flame and wall-combustion. For the purpose of calculation of turbulence intensity and other turbulent sizes proper sub-model of turbulence should be applied. In this paper K-k sub-model of turbulence is used. Experimental data for several operating points of the experimental engine Hatz 1D81 were measured at the Laboratory for engines and vehicles for the purpose of calibration of the simulation model developed in the commercial software package AVL Boost. After the validation and calibration of simulation model numerical analysis of the effects of various forms of piston crown and cylinder head on the indicated mean effective pressure and effective power of the engine was carried out. During the simulation all other geometrical features of the engine and constants of individual sub-models remained unchanged, which ensured separation of the impact of the geometry of combustion chamber on engine performance. At the end simulation results are presented, compared and explained. Conclusions about the possibilities of cycle-simulation, with respect to the analysis of a change in the geometry of the combustion chamber on the performance of SI engines, and guidelines for the development of improved combustion chamber are also given.
Keywords
Keywords (english)
Languagecroatian
URN:NBNurn:nbn:hr:235:115974
Study programmeTitle: Mechanical Engineering
Study programme type: university
Study level: undergraduate
Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
Type of resourceText
File originBorn digital
Access conditionsOpen access
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Created on2019-05-22 18:35:35