مشخصات پژوهش

This study investigated the effects of rainfall on flow separation and the aerodynamic performance of single elementandslattedNACA0012airfoilsbyusingamathematicalmodel developedwiththe commercialcomputationalfluiddynamicssolverANSYSFLUENT18.2. Atwo-way momentumcoupled Eulerian–Lagrangianmultiphaseapproach wasusedto simulate the formation ofthe waterfilmlayer onthe airfoil’ssurface. Accordingto the results, verylow valuesofthe lift-to-drag ratio atlow anglesofattackreflected severe degradationofthe aerodynamicperformanceofthe airfoilin the presenceofwateraccu-mulatedonits surface. Theimpact ofrain dropletsonthe leading-edge slat surface led to less wateraccumulatingonthe mainsectionofthe airfoil.In particular,the maximum waterfilmmassconcentratedonthe airfoilsurfacedecreasedfrom 15gto 1gcompared withthe singleelementairfoil.Hence,the thickness ofthe waterfilmlayer wasnotsuf-ficientlylarge to significantlyaffectthe aerodynamiccoefficientsofthe slattedairfoil,es-peciallythe maximumlift coefficient,comparedwiththe thicker waterfilmlayer onthe singleelementairfoil.In addition,the useofslatsclearlyenhancedthe aerodynamicco-efficientsandincreased the stallanglefrom 13°to 22°in dryconditions,andfrom 16°to 24°in rainyconditions.Slatsalsosignificantlydecreasedtheboundarylayer thicknessand delayedthe separationathigheranglesofattack.