AERODINAMIČNE KARAKTERISTIKE NESTACIONARNEGA ZASTOJA NA PROFILU S809 PRI NIZKIH REYNOLDSOVIH ŠTEVILIH
Povzetek
Opravljena je bila raziskava, kjer smo preučevali karakteristike nestacionanega statičnega zastoja na profilu S809, katerega aerodinamične karakteristike so reprezentativne za vetrne turbine z horizontalno osjo. Eksperimentalno je zelo težko preučevati ta pojav, še posebej kadar želimo preučevati odcepljanje toka na rotirajočih lopaticah. Izvedba meritev v zračnem tunelu oziroma simulacij računalniške dinamike tekočin je primernejše. Z namenom raziskovanja nestacionarnega statičnega zastoja glede aerodinamičnih karakteristik S809 profila je bila opravljena primerjalna študija, tako so bili primerjani eksperimentalni in numerični rezultati položaja odcepitve toka, porazdelitve tlaka po profilu in hitrostih profilov vključno z oscilacijami hitrosti. Eksperimentalni rezultati so bili pridobljeni z uporabo PIV (meritev hitrosti z odslikavo delcev) in pri različnih napadnih kotih. Pri nizkih napadnih kotih nismo zaznali odcepitve toka, pri napadnem kotu 9.6° je odcepljen vrtinec zavzemal 50% dolžine tetive profila, pri napadnem kotu 20° zastojni vrtinec obsega ves profil. Opazovana področje odcepitve ni bilo stacionarno ampak smo ugotovili, da oscilira okrog njene srednje pozicije v intervalu ±10% dolžine tetive. Uporabljena turbulentna modela, k-ε in SST, v 2D časovno odvisnih simulacijah nista napovedala teh oscilacij, čeprav so se numerični rezultati dokaj dobro ujemali z eksperimentalno pridobljenimi, še posebej polja povprečne hitrosti in polja vrtinčnosti na sesalni strani profila pri uporabi SST turbulentnega modela.
Prenosi
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