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Naslov: Design of an Efficient Fan Steering Strategy for Efficient Cooling of Engine Peripheral Components during Vehicle Thermal Soak : magistrsko delo ID Pečnik, Tjaša (Avtor)ID Zadravec, Matej (Mentor) Več o mentorju... ID Wolff, Daniel (Komentor) MAG_Pecnik_Tjasa_2024.pdf (13,61 MB, Vsebina bo dosegljiva po 26.03.2027)MD5: F15AE33BAA754CFFB0192FADD55E3E28 Angleški jezik Magistrsko delo/naloga 2.09 - Magistrsko delo FS - Fakulteta za strojništvo The aim of this Master's thesis was to find a mathematical correlation between various fan momentum fields for a fan which is used for cooling the underhood area of a car. The correlation had to link a known momentum field to all possible momentum fields related to fan rotation speed and car velocity. With this correlation, new alternative fan steering strategies can be used to cool the vehicle underhood area. An already functioning RBM (Rigid Body Motion) simulation was used as a base, since it already gave satisfying results in the past. With this simulation file, several tests were run to ensure that the results really converge nicely. In this way it was established that the results are accurate enough for further use. After obtaining the results, a set of 30 simulation files was calculated. The simulations were a combination of different fan rotation speeds and car velocities. After the set was done, the results were analysed using various computer software (Star-CCM+, MS Excel and Matlab). It was concluded that a polynomial approach for the momentum field was a suitable option but to add some additional complexity, surface equations were used. To obtain the equations, tables with different results were put into Matlab and the program did the rest. The result were two sets of three surface equations with x and y values. In both cases, x represented the rotation speed of the fan and y represented the car velocity in one case and the delta pressure between two evaluation surfaces in the other. After that it was time to implement the newly acquired surface equations in a Star-CCM+ simulation file. The old simulation file was again used as a base, but new field functions were put in with the help of which the UDMS (User Defined Momentum Source) is being changed. Both types of surface equations were tested and calculated. In the end, it was decided to go with the one where the delta pressure on two evaluation surfaces is being used as the y value. One surface was placed in front of the fan and the other after the fan. The final step was to test different fan steering strategies. The usual cooling procedure consists of a phase where the fan cools for a specific amount of time with a defined rotation speed and then turns off. Temperatures on critical points around the engine and in the underhood area of the car are being looked at as a result. The first strategy was to run the fan at the same speed as usual, but gradually slow it down in uniform steps so that the shut down time remains the same. With this approach, the highest temperature values were actually lower than usual, but certain temperature probes became warmer as the fan speed decreased. Nevertheless, the temperatures at the end were very similar. The second tested strategy was inspired by the idea of potentially saving some battery energy if we could somehow manage to cool the underhood area quicker. In this case, the fan ran for a short time at a high rotation speed and after that at a slightly lower speed. Then it was turned off for a few minutes and subsequently switched back on. The maximum temperature in this scenario reached even higher values. The reason for this was that the fan blew warm air toward certain measurement points, causing them to heat up further. The temperatures at the end of the simulation were similar to those in the previous two cases. In conclusion, it is indeed possible to steer a fan momentum field with the help of field functions and equations which describe the relationship between different fan rotation speeds and car velocities. fan, momentum, RBM, CFD, thermal soak Maribor Maribor [T. Pečnik] 2024 1 spletni vir (1 datoteka PDF (XVIII, 130 f.)) 20.500.12556/DKUM-87351 62-712.3:621.43.016(043.2) 192132611 02.04.2024 68 0 KTFMB - FS Kopiraj citat

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## Licence

Licenca: CC BY-NC-ND 4.0, Creative Commons Priznanje avtorstva-Nekomercialno-Brez predelav 4.0 Mednarodna http://creativecommons.org/licenses/by-nc-nd/4.0/deed.sl Najbolj omejujoča licenca Creative Commons. Uporabniki lahko prenesejo in delijo delo v nekomercialne namene in ga ne smejo uporabiti za nobene druge namene. 12.03.2024

## Sekundarni jezik

Jezik: Slovenski jezik Zasnova učinkovite strategije upravljanja ventilatorja za učinkovito hlajenje perifernih komponent motorja med toplotno obremenitvijo vozila Cilj te magistrske naloge je bil najti matematično korelacijo med različnimi vrtilnimi količinami ventilatorja za hlajenje območja pod pokrovom avtomobila. Korelacija je morala povezati znano vrtilno količino ventilatorja z vsemi možnimi vrtilnimi količinami, vezanimi na hitrost vrtenja ventilatorja in hitrost avtomobila. S to korelacijo je mogoče uporabiti nove alternativne strategije krmiljenja ventilatorja za hlajenje podvozja avtomobila. Za osnovo je bila uporabljena že delujoča RBM (Rigid body motion) simulacija, saj je v preteklosti že dala dovolj dobre rezultate. S slednjo je bilo izvedenih nekaj testov, da so rezultati resnično dobro konvergirali. Na ta način je bilo zagotovljeno, da so rezultati dovolj dobri za nadaljnjo uporabo. Po pridobitvi rezultatov je bil izveden set tridesetih simulacij, katere so bile kombinacija različnih hitrosti vrtenja ventilatorja in hitrosti avtomobila. Po izvedbi celotnega seta tridesetih simulacij, so bili rezultati analizirani s pomočjo različnih računalniških programov (Star-CCM+, MS Excel in Matlab). Ugotovljeno je bilo, da je polinomski pristop najprimernejši za vrtilno količino, za dodatno kompleksnost pa so bile uporabljene površinske enačbe. Za pridobitev teh enačb so bile v Matlab vstavljene tabele z različnimi rezultati, program pa je naredil preostanek. Rezultat sta bila dva niza treh površinskih enačb z vrednostmi x in y. Vrednost x je v obeh primerih predstavljala hitrost vrtenja ventilatorja, vrednost y pa je v enem primeru predstavljala hitrost avtomobila, v drugem pa razliko tlaka na dveh površinah, s pomočjo katerih je bil slednji beležen v področju pod pokrovom avtomobila. Za tem je sledila implementacija novo pridobljenih površinskih enačb simulacijsko datoteko Star-CCM+. Za osnovo je bila ponovno uporabljena stara simulacija, kamor pa so bila vnesena nova funkcijska polja, s pomočjo katerih se spreminja vrtilna količina ventilatorja (UDMS – User defined momentum source). Obe vrsti površinskih enačb sta bili testirani in izračunani, na koncu pa je bila izbrana tista, kjer je za vrednost y uporabljena razlika tlakov na dveh površinah v območju pod pokrovom avtomobila. Ena je bila postavljena pred ventilator, druga pa za njim. Zadnji korak je bil preizkus različnih strategij krmiljenja ventilatorja. Običajni postopek hlajenja je sestavljen iz faze, kjer ventilator določen čas hladi z določeno hitrostjo vrtenja in se nato ugasne. Preučujejo se temperature na kritičnih točkah v okolici motorja pod pokrovom avtomobila. Prva strategija je bila sledeča: zagnati ventilator z enako hitrostjo kot običajno, vendar ga postopoma upočasnjevati v enakomernih korakih, da je na koncu čas zaustavitve še vedno enak. S tem pristopom so bile najvišje vrednosti temperature dejansko nižje od običajnih, vendar so se določene točke med procesom, ko se je hitrost ventilatorja zniževala, še dodatno ogrele. Kljub temu pa so bile temperature na koncu simulacije zelo podobne. Druga preizkušena strategija je bila zasnovana po navdihu, da bi morda lahko prihranili nekaj baterijske energije, če bi nekako uspeli v krajšem času ohladiti območje pod pokrovom avtomobila. Ventilator je v tem primeru za kratek čas deloval z visoko hitrostjo, nato pa z nekoliko manjšo. Nato je bil za nekaj minut izklopljen in potem ponovno vklopljen. Izkazalo se je, da maksimalne temperature v tem primeru dosegajo še višje vrednosti. Razlog za to je bil v tem, da je ventilator pihal topel zrak v smeri nekaterih merilnih točk, ki so se zaradi tega še bolj ogrele. Temperature na koncu simulacije pa so bile kljub vsemu podobne kot v prejšnjih dveh primerih. Skratka, ugotovljeno je bilo, da je vsekakor mogoče krmiliti vrtilno količino ventilatorja s pomočjo funkcijskih polj in enačb, ki opisujejo razmerje med različnimi hitrostmi vrtenja ventilatorja in hitrostmi avtomobila. ventilator, vrtilna količina, CFD, RBM, toplotna obremenitev

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