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# Aerodinamics

Bernoulli’s Theorem Aerodinamics Forces Nondimensional Coefficients Wind Tunnel

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### Aerodinamics

1. 1. Aerodinamics Forces Focus 1 Bernoulli’s Theorem 2 Aerodinamics Forces 3 Nondimensional Coefﬁcients 4 Wind Tunnel c www.mechanical–enginering.name
2. 2. Aerodinamics Forces Bernoulli’s Theorem Bernoulli’s theorem states that the sum of kinetic energy 1/2qV2 and potential energy (pressure p) is constant and which can be expresed as follows 1 2 qV2 + p = constant , (1) excluding the forces of gravity. c www.mechanical–enginering.name
3. 3. Aerodinamics Forces Bernoulli’s Theorem T2 + Velocity - Pressure - Velocity + Pressure T1 TV Td c www.mechanical–enginering.name
4. 4. Aerodinamics Forces Bernoulli’s Theorem The ﬂows can be considered as two pipes, an upper one T1 toward the ventral side of the plate and a lower one T2 toward the dorsal side. In the dorsal part the airﬂow is forced to travel to rejoin the exiting streamlines with an increase in speed and a loss of pressure energy. In the ventral part, the trajectories are shorter, due to lower velocity, and the area Tv of local pressure is greater. c www.mechanical–enginering.name
5. 5. Aerodinamics Forces Aerodinamics Forces V R -P F j c www.mechanical–enginering.name
6. 6. Aerodinamics Forces Nondimensional Coefﬁcients The component of the resultant parallel to airﬂow is the drag R CR = f (Re) = R 1 2 qSV2 , (2) with S the projected frontal area. The component normal to the ﬂow is the downforce −P and its nondimensional coefﬁcient −CP: CP = f (Re) = − P 1 2 qSV2 , (3) c www.mechanical–enginering.name
7. 7. Aerodinamics Forces Center of pressure C R -P F j Xp c www.mechanical–enginering.name
8. 8. Aerodinamics Forces Center of pressure The point where the line of action of aerodinamics force F encounters the body is called the center of pressure. It is located at a distance XP from the leading edge, which varies according to the angle of attack, so that the nondimensional ratio Xp/C, with chord C, varies from 0 to 0.5 for angles to attack from 0 ◦ to 90 ◦ . The curvature, in the plate, creates an angle j between the slope of the tailing edge and the chord line. c www.mechanical–enginering.name
9. 9. Aerodinamics Forces NACA Proﬁle 4412 c www.mechanical–enginering.name
10. 10. Aerodinamics Forces NACA Proﬁle 4412 V R -P F i i −Cp CR 3.6 0.00 0.007 0.0 0.28 0.012 −2.0 0.43 0.019 −4.0 0.58 0.028 −6.0 0.73 0.041 −8.0 0.88 0.056 −10.0 1.02 0.076 −12.0 1.15 0.096 −14.0 1.28 0.121 c www.mechanical–enginering.name
11. 11. Aerodinamics Forces Wind Tunnel V V=0Laminar Turbulent c www.mechanical–enginering.name