تأثير استخدام الحدبات في الخواص الديناهوائية للأجنحة عند أعداد رينولدز الواطئة

الملخص EN

The effect of using bumps on the aerodynamic characteristics of airfoil at low Reynolds numbers is presented in this research.

A theoretical study was done on the (NACA 4418) airfoil consist of bumps that have radius (2% c) on the upper and lower surfaces at (Re=25×103).

Experimental study was also done on the control of flow around (NACA 0015) airfoil of backward facing step with and without bumps inside the step at (Re=4.4×105).

Theoretically the (Fluent 6.3) package was utilized for simulating the flow around the airfoils.

Experiments were done in a low-speed wind tunnel in order to obtain the pressure distribution on the airfoil surface and lift and pressure drag coefficients.

The airfoils used in the experimental study were the basic airfoil, airfoil of backward facing step on the lower surface with and without bumps, and airfoil of backward facing step on the upper surface with and without bumps.

The theoretical results illustrate the benefit of using bumps on the lower and upper surfaces of the (NACA4418) airfoil.

The laminar separation bubble was delayed.

Also the theoretical and experimental results show the benefit of using bumps inside the steps on the lower or upper surfaces of the airfoil.

The (Clmax) was increase by (25.04%) with respect to the basic (NACA 0015) airfoil and by (7.14%) with respect to the airfoil with smooth step on the lower surface.

When using step and bumps on the upper surface the (Clmax) was increase by (16.85%) with respect to the basic (NACA 0015) airfoil and (5.86%) with respect to the airfoil with smooth step on the upper surface.