Termomehanička numerička analiza ispušnog sustava motora

master's thesis

• Title (english): Thermomechanical numerical analysis of engine exhaust manifold
• Author: Andrej Šubat
• Mentor: Zdenko Tonković (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2017-05-19, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Raspodjela temperatura po strukturi bilo koje komponente motora s unutarnjim izgaranjem je definirana temperaturom plinova (koji predstavljaju termalno opterećenje), stanjem okoliša, geometrijom i materijalnim svojstvima te mehanizma prijenosa topline i njegovim intenzitetom. To se također odnosi i na ispušnu granu motora s unutarnjim izgaranjem te se može pretpostaviti da će konfiguracija (orijentacija) ugradnje motora u prostoru motora i pozicija ugradnje ispušne grane utjecati na raspodjelu temperatura po njenoj strukturi. Do tog učinka dolazi zbog promjene slike strujanja zraka u prostoru motora, uzrokovane gibanjem vozila, što posljedično određuje intenzitet prijenosa topline konvekcijom između ispušne grane i njenog okoliša.

Cilj ovog diplomskog rada je utvrditi razlike do kojih eventualno dolazi u pogledu intenziteta prijenosa topline i rezultirajuće raspodijele temperatura po strukturi analiziranih komponenata između tri standardne konfiguracije ugradnje motora i pozicije ispušne grane koristeći pritom metodu konačnih elemenata.

Tri standardne konfiguracije su simulirane na istom proračunskom modelu varirajući samo ambijentalne termalne rubne uvijete nametnute na površine komponenata motora koje su izložene direktnom strujanju zraka u prostoru motora.

Novo definirani i nametnuti termalni rubni uvjeti su određeni na temelju rezultata nekoliko 3D analiza strujanja zraka kroz prostor motora izvedenih primjenom računalne dinamike fluida koje je omogućila tvrtka AVL List GmbH.

U konačnici je ispitan utjecaj različite raspodijele temperatura i temperaturnih gradijenata po strukturi između ispitivanih konfiguracija na termomehanički zamor ispušne grane motora.

Numeričke simulacije procijene životnog vijeka ispušne grane, za sve konfiguracije, izvedene su prema AVL-ovoj provjerenoj proceduri za ispitivanje termomehaničkog zamora.

Simulacije provedene u okviru ovog diplomskog rada izvedene su u programskom paketu SIMULIA Abaqus® koji razvija tvrtka Dassault Systèmes.

Abstract (english)

Structural temperature distribution of any internal combustion engine component is defined by the gas temperature (thermal load), surrounding conditions, geometry, material properties and the overall intensity of heat exchange mechanisms. This also applies to the internal combustion engine exhaust manifold and it can be presumed that installation configuration (orientation) of the engine and the mounting position of the exhaust manifold in the engine compartment will influence structural temperature distribution. The reason behind this effect is the alteration of the underhood airflow stream, induced by vehicle motion, which defines convective mode of heat exchange process between exhaust manifold and its surrounding.

The aim of this Master’s thesis is to investigate the differences between three standard engine and exhaust manifold installation configurations in passenger cars with respect to the heat exchange and the resulting structural temperature distribution using the finite element method approach.

Three standard configurations are simulated on the same finite element model by varying ambient heat transfer boundary conditions applied to surfaces exposed to underhood airflow stream.

Newly defined and applied ambient heat transfer boundary conditions are based on the results of multiple 3D computational fluid dynamics underhood airflow simulations provided by AVL List GmbH.

Finally, influence of structural temperature and structural temperature gradient variation between each model variant on exhaust manifold thermo-mechanical fatigue life is investigated.

Thermo-mechanical fatigue analyses are carried out in accordance with AVL’s validated and tested thermo-mechanical fatigue simulation procedure for internal combustion engines. The numerical models of internal combustion engines were also provided by AVL List GmbH.

SIMULIA Abaqus® finite element software, developed by Dassault Systèmes is used in the scope of this thesis.

• Keywords: Termomehanički zamor; Niskociklički zamor; Zamor ispušne grane; Metoda konačnih elemenata; Termalna analiza; Sekvencijalno spregnuta termomehanička analiza
• Keywords (english): Thermo-mechanical fatigue; Low cycle fatigue; Exhaust manifold fatigue; Finite element method; Thermal analysis; Sequentially coupled thermo-mechanical analysis
• Language: english
• URN:NBN: urn:nbn:hr:235:481227
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 19:32:19