Search

U teorijskom dijelu rada opisana je povijest razvoja i primjene turbopunjača, princip rada motora s turbopunjačem te dijelovi turbopunjača, s naglaskom na materijalima i proizvodnim postupcima za njihovu izradu i najčešćim kvarovima. U eksperimentalnom dijelu rada analizirana je havarija turbopunjača izuzetog iz gospodarskog vozila. Na istrošenim dijelovima kompresora i turbine turbopunjača provedena je kemijska analiza metodom fluorescentne spektrometrije, ispitivanje tvrdoće metodom Vickers te analiza mikrostrukture svjetlosnom mikroskopijom. U diskusiji rezultata je opisan slijed događaja koji su prethodili havariji turbopunjača i glavni uzrok, lom spojnog vratila koji je u konačnici rezultirao havarijom i prestankom rada turbopunjača. The theoretical part of the paper describes the history of the development and application of turbochargers, the principle of operation of engines with turbochargers, and parts of turbochargers, with an emphasis on materials and production procedures for their manufacture, and the most common failures of turbochargers. In the experimental part of the work, the failure of a turbocharger removed from a commercial vehicle was analyzed. Chemical analysis using the fluorescence spectrometry method, hardness testing using the Vickers method, and microstructure analysis using light microscopy were performed on the worn parts of the compressor and turbocharger turbine. In the discussion of the results, the sequence of events preceding the turbocharger failure and the main cause, the fracture of the connecting shaft, which ultimately resulted in the failure and cessation of operation of the turbocharger, are described.

U ovom radu opisan je nulto-dimenzionalni model motora s unutarnjim izgaranjem, prednabijanjem i hlađenjem stlačenog zraka za izgaranje. Ukratko su objašnjeni teorijski principi rada te prednosti i nedostaci pojedinih klasa modela. Dan je opis matematičkog modela svakog od glavnih dijelova motora koji su međusobno povezani u jednu cjelinu koja čini matematički model cijelog motora. Model motora se izradio po uzoru na moderni šesterocilindrični dizelski motor s prednabijanjem i hlađenjem stlačenog zraka N57D30O0 njemačkog proizvođača vozila BMW. Dan je sažeti tehnički opis glavnih dijelova i sustava navedenog motora uz navedene glavne tehničke karakteristike motora. Za provedbu simulacija rada motora korišten je računalni program Engine Simulation britanske tvrtke Lotus Engineering. Usporedbom rezultata simulacije rada motora s vrijednostima snage i okretnog momenta stvarnog motora zaključilo se da je napravljeni model motora valjan te da vjerno opisuje rad stvarnog motora uz mala odstupanja vrijednosti dobivenih simulacijom od stvarnih vrijednosti motora. Analizirao se utjecaj tlaka prednabijanja na rad motora i turbopuhala te utjecaj temperature vanjskog zraka u okolini motora na njegov rad te na rad hladnjaka stlačenog zraka. Također su se usporedili rezultati simulacije rada motora sa i bez hladnjaka stlačenog zraka., This master’s thesis describes the workings of a zero-dimensional thermodynamic model of a diesel powered, turbocharged internal combustion engine with charge air cooling. Theoretical working principles of various mathematical model types (regarding their dimensionality) are briefly described, as are their respective advantages and disadvantages. Mathematical models of each of the main individual engine components are described. When combined, those individual models make up the model of the whole engine. The virtual engine model was modelled after a modern six-cylinder turbocharged engine with charge air cooling, the BMW N57D30O0 engine. A brief technical description of the main parts and systems of the aforementioned engine is given, as are its main technical parameters. Engine Simulation, a computer program made by Lotus Engineering, was used to carry out the engine run simulations. By comparing the results of the engine run simulations with the power and torque values of the real engine it is concluded that the engine model created is valid and that it correctly describes the operation of the real engine with small deviations between the values obtained by the simulation and the actual engine values. The influence of varying boost pressure on the engine and turbocharger operation was analysed, as well as the influence of the outside air temperature on its operation and the operation of the charge air cooler. The simulated results of the engine running with and without a charge air cooler were also compared.

U ovom radu analiziran je dvotaktni motor s prednabijanjem namijenjem za pogon zrakoplova generalne avijacije. U novije vrijeme zbog sve većih zahtjeva za smanjenjem potrošnje goriva i sve strožim propisima emisija ispušnih plinova, četverotaktni motori su istisnuli uporabu dvotaktnih motora. Analizom je pokazano kako se primjenom izravnog ubrizgavanja i pažljivim konstruiranjem kanala za izmjenu radnog medija mogu postići sasvim zadovoljavajući rezultati potrošnje goriva i emisije ispušnih plinova, istovremeno iskorištavajući veću snagu i ujednačeniji moment dvotaktnog motora. Za simulaciju rada motora koristio se komercijalni programski paket AVL BOOSTTM v2013.2. Na početku je izrađena simulacija motora s pojednostavljenim modelom turbopunjača te su uspoređeni dobiveni rezultati s maksimalno očekivanom efektivnom snagom pri maksimalnoj brzini vrtnje motora. S ciljem što točnije analize definirano je nekoliko kompletnih mapa rada turbopunjača te su uspoređeni rezultati i odabran je turbopunjač koji najbolje odgovara analiziranom motoru. Na kraju je analiziran utjecaj povećane nadmorske visine na rad motora te je opisan koncept dodatnog kompresora pogonjenog elektromotorom (eng. e-booster) kojim se može kompenzirati gubitak snage uslijed niskog tlaka okoline. In this thesis the cycle-simulation of two stroke spark ignition turbocharged engine for the application in general aviation was analyzed. Most recently due to the increasing demands on reduction in fuel consumption and increasingly stringent exhaust emissions regulations, four-stroke engines have squeezed the use of two-stroke engines. The analysis has shown that by using direct injection and by detailed design of intake and exhaust ports, two stroke engines can achieve quite satisfactory results of fuel consumption and exhaust emissions while simultaneously taking advantage of greater power and a more balanced torque of the two-stroke engine. For engine simulation, the commercial version of AVL BOOSTTM v2013.2 software package was used. At the beginning a simulation of the engine with a simplified turbocharger model was made and the obtained results were compared with the maximum expected brake power at maximum engine speed. For a more accurate analysis, several full turbocharger maps have been defined and the results were compared with simplified model and a turbocharger is selected that best suits the analyzed engine. Finally, the influence of increased altitude on engine operation was analyzed and the concept of an additional compressor powered by an electric motor (e-booster) was described to compensate for the loss of power due to low ambience pressure.

U ovom radu su opisani sustavi turbonabijanja brodskih četverotaktnih i dvotaktnih dizelskih motora. Povećanje tlaka zraka korištenog za ispiranje i izgaranje uvelike je doprinijelo rastu snaga i korisnosti motora, kao i smanjivanju dimenzija istog. Analizom vodećih proizvođača turbopuhala poput ABB i MAN Diesel&Turbo, opisana je sama konstrukcija turbopuhala te različiti sustavi i metode turbonabijanja. Budući da se glavne komponente turbopuhala rotiraju velikom brzinom, podmazivanje i održavanje sustava je neophodno. Održavanje se provodi kroz postupke čišćenja turbopuhala i obavljanjem poslova i kontrola definiranih od strane proizvođača. U radu je također definirano pumpanje turbopuhala, jedan od glavnih problema u radu koji se javlja u određenim operativnim uvjetima te preporuke za izbjegavanje istog. This paper describes turbocharging principles in four-stroke and two-stroke engines. Increasing the pressure of air supplied to the engine have played imporatnt role in engine efficiency by means of power and downsizing. Construction of turbochargers and various methods of turbocharging have been described in this paper by analayzing some of the main manufractures like ABB and MAN Diesel&Turbo. Since the main components of turbocharger are rotate at high velocity, lubrication and maintanance must be provided. Maintanance is carried out by washing of turbocharger and following the instructions given by the manufracturer. Also, one of the main troubleshoot in turbocharger operation, pumping, is explained.

Kao odgovor na zahtjeve tržišta razvijena su mnoga rješenja za smanjivanje vremena odziva pri nagloj promjeni opterećenja turbonabijenog motora. Jedno od tih rješenja je primjena turbopunjača s turbinom promjenjive geometrije. U svrhu ispitivanja utjecaja primjene turbopunjača s turbinom promjenjive geometrije na vrijeme odziva pri nagloj promjeni opterećenja Ottovog motora provedene su simulacije u računalnom programu AVL BOOST. Prikazan je način odabira kompresorske mape i usporedba odziva dva modela s različitim turbopunjačima pri različitim brzinama vrtnje motora te su naznačena vremena potrebna za postizanje 99% odnosno 99,9% maksimalne vrijednosti za svaki model. Također je prikazan utjecaj momenta inercije turbopunjača na vrijeme odziva. Rezultati su pokazali da primjena turbopunjača s turbinom promjenjive geometrije može dovesti do smanjenja vremena odziva pri naglim promjenama opterećenja za 39,77%. Iz rezultata je također vidljivo da promjena inercije rotacijskih masa turbopunjača u iznosu od 20% dovodi do promjene vremena odziva od 8,2%. In response to market demands, many solutions for reducing response time to a sudden load change in turbocharged engines have been developed. One of these solutions is the use of variable nozzle turbine turbocharger. For the purpose of testing the influence of the variable nozzle turbine turbocharger on response time to a sudden load change of SI engine, simulations were conducted in computer program AVL BOOST. The compressor map selection method and comparison of the load response for two models with different turbochargers at different engine speeds are shown with the time required to achieve 99% and 99.9% of maximum values marked for each model. The influence of the turbocharger moment of inertia on response time is also shown. Results have shown that the use of variable nozzle turbine turbocharger can lead to 39.77% reduction in response time to a sudden load change. The results have also shown that the reduction in turbocharger moment of inertia by 20% leads to response time reduction by 8.2%

Studenti Fakulteta Strojarstva i Brodogradnje u sklopu FSB Racing Team-a, već se godinama natječu na Formula Student natjecanjima. Formula Student je međunarodno natjecanje studenata tehničkih fakulteta u kojem studenti osmišljavaju, konstruiraju i izrađuju svoj trkaći bolid prema određenim pravila. Dosadašnji razvijeni bolidi FSB Racing Team-a nisu koristili turbopunjač, niti je ta mogućnost bila detaljno razrađena, iako je pravilnikom dopušten. S obzirom da pravilnik zahtjeva specifičan smještaj turbopunjača, pri čemu se kompresor turbopunjača mora nalaziti iza restriktora kojim se ograničuje najveći mogući protok zraka kroz motor, postavlja se pitanje da li bi njegova primjena donijela značajno poboljšanje momenta i snage motora. Također, važno je za napomenuti da je motor koji koristi bolid FSB Racing Team-a i u koji bi se ugrađivao turbopunjač jednocilindarski. U sklopu ovog rada napravljen je, u računalnom programu AVL Boost, simulacijski model postojećeg motora i simulacijski model istog tog motora s ugrađenim turbopunjačem. Kako bi se odabrao odgovarajući turbopunjač od dva ponuđena, motor je prethodno parametriziran uz primjenu pojednostavljenog modela turbopunjača. Međutim, pošto se nije moglo jednoznačno utvrditi koji je turbopunjač bolji za odabrani motor, provedene su simulacije za oba turbopunjača, te je prikazana usporedba rada motora bez prednabijanja i motora s različitim turbopunjačima. Students of Faculty of Mechanical Engineering and Naval Architecture within the FSB Racing Team have been competing in Formula Student competitions for years. Formula Student is an international competition for students from faculities of technical studies in which students develop, design and construct their own racing car following certain rules. Formerly developed cars by FSB Racing Team have not been fitted with the turbocharger, nor has this possibility been elaborated in detail, although the rules permit usage of a turbocharger. Given that the rulebook requires a specific turbocharger's accommodation, such that the compressor must be behind the restrictor that limits the maximum possible airflow through the engine, the question arises as to whether its application would significantly improve engine's torque and power figures. Also, it is important to note that the engine used by the FSB Racing Team car and in which a turbocharger would be fitted, is a single-cylinder engine. In this thesis, a simulation model of the existing engine and a simulation model of the same engine fitted with a turbocharger were developed using AVL Boost software. In order to select between the two available turbochargers, the engines were parameterized with the use of a simplified turbocharger model. However, since the exact determination of better turbocharger for an engine of choice was not possible, simulations were carried out for both turbochargers and the comparison between normally aspirated engine and the engines with different turbochargers is given.