drag & lift solved problems - philadelphia university · lift force on body: a s bc p = = 6....
TRANSCRIPT
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 11
SOLVED PROBLEMS
CHAPTER (11)
DRAG & LIFT
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 22
SUMMARY
1. Drag Force on Body:
2. Drag force on body is a combination of Form Drag (Pressure
Forces) and Skin Friction Drag (Shear Stress Forces).
3. Coefficient of a Drag of a Sphere For Re<0.5 (Stokes Drag):
4. Frequency of vortex Shedding is Given by (St = Strouhal) Number:
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 33
5. Lift Force on Body: cbSAp ==
6. Lift Coefficient For a Symmetric Two – Dimensional Wing (No tip
effect):
7. Drag Coefficient Corresponding to the Minimum Induced Drag:
8. Streamlining at high Re reduces the drag due to pressure and increase
the viscous drag.
9. Streamlining at Low Re increases the drag due to viscous forces.
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 44
Problem (11.7)
h=75m
D=2.5m
DF
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 55
Problem (11.17)
D=0.5msmV 3=
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 66
Problem (11.20)
VFPPower ×==
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 77
Problem (11.27)
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 88
Problem 11.33 (p. 476)Problem 11.33 (p. 476)
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 99
Problem (11.33)
25% reduction in drag when vanes introduced
Given projected area (Ap)=8.36 m2
CD without vanes = 0.78
V=100 km/hr
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 1010
Problem (11.38)
IbfWSPHERE 27=
Sphere diameter = 1 ft
S.G = 0.85
?min =alTerV
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 1111
Problem (11.38)
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 1212
Problem (11.49)
L=80 cm, d = 20 cm
Weight = 200 N
?min =alTerV
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 1313
Problem (11.49)
09/12/201009/12/2010 Dr. Munzer Ebaid Dr. Munzer Ebaid 1414
Problem (11.73)
( )( ) 4.1
2.18
=
=
StallingL
LandingL
C
CspeedstallingthanfastersmisspeedLanding
09/12/201009/12/2010 Dr. Dr. MunzerMunzer EbaidEbaid 1515
THE END