20.500.12556/RUL-119349 Analiza vpliva zložljivega propelerja in različnih geometrij propelerske kape na upor tekmovalnega jadralnega modela letala Analysys of the influence of a folding blade propeller and different spinner geometry on a competition model aircraft drag V tem delu smo se osredotočili na analizo upora jadralnega modela letala, ki ga povzroča zložljivi propeler, ko ne obratuje. Upor smo izračunali z računalniško dinamiko tekočin, saj so natančne meritve na pravem modelu težko izvedljive. Pri izračunih smo se omejili na področje trupa pred krilom. Izračunali smo tlačno-hitrostno polje v okolici prednjega dela trupa letala, v petih različnih konfiguracijah: trup brez propelerja, trup z navadnim zložljivim propelerjem (z odprtino in brez odprtine za hlajenje motorja) in trup s propelerjem, ki se bolje prilega trupu (z odprtino in brez odprtine za hlajenje motorja). Uporabili smo nestrukturirano računsko mrežo, kateri smo spremenili tako razsežnost kot gostoto, da smo zagotovili neodvisnost od računske mreže. Za izračune smo uporabili orodje Ansys Fluent. Pri trupu brez propelerja smo izračune opravili z laminarnim tokom. Ko je propeler nastavljen na trup, smo izračune izvedli s turbulenčnim modelom Spalart-Allmaras. Ker moramo oceniti vpliv propelerja na upor celotnega letala, smo s sistemom GPS in z barometričnim višinomerom izmerili karakteristike modela letala. Ugotovili smo, da prisotnost propelerja poveča zračni upor letala za približno 2 %. Navaden zložljivi propeler ustvari intenzivnejšo turbulenco kot prilegajoči se propeler. Razlika upora dveh propelerjev je nekje 0,1 %. Rezultati simulacij kažejo, da prisotnost odprtine za hlajenje zmanjšuje upor letala. In this work we focused on the aerodynamic drag caused by a folding blade propeller while in the folded position, on a glider model airplane. The drag was calculated using computational fluid dynamics, because of the inability to perform accurate measurements directly on the glider model. Calculations were performed for the part of the fuselage ahead of the wing only. Calculations of five different geometries were performed: a clean fuselage, a fuselage with a standard folding propeller (with and without the presence of a cooling duct for the motor) and a fuselage with a modified folding propeller, which fits the fuselage better (with and without the presence of a cooling duct for the motor). An unstructured mesh was used, calculations for different mesh extent and density were performed in order to ensure a mesh independent solution. When performing calculations for the clean fuselage, a laminar flow was assumed. While performing calculations for the fuselage with a propeller, the Spalart-Allmaras turbulence model was used. All calculations were performed using the Ansys Fluent software. For the estimation of the total drag of the model airplane, measurements were performed using a GPS system coupled with a barometric altitude sensor. We found out that the presence of a propeller increases the glider's drag by almost 2%. The propeller's shape also influences the amount of drag. The standard propeller creates more turbulence. The difference in drag caused by the two propellers is about 0,1%. Our results indicate that the cooling duct decreases the drag. zložljiv propeler zračni upor jadralno letalo računalniška dinamika tekočin folding propeller aerodynamic drag glider computational fluid dynamics true false false [E. Zubalic] Slovenski jezik Angleški jezik Diplomsko delo/naloga 2020-09-08 08:32:27 2020-09-08 08:32:30 2023-11-17 08:07:36 0000-00-00 00:00:00 2020 0 Ljubljana 0 XXII, 44 str. 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 629.7.035.5:533.6.013.12(043.2) 223720 32792579 5975.pdf 5975.pdf 1 DBDF2EF605EA7ACFA7F22D23AB8E0860 eced8bee344b853f5547f5ae7017a00868a3ba672edc12f81e42e0508c98336a cd87532e-a1b9-11eb-a523-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=134051 Fakulteta za strojništvo 0 0 0