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Peridot
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A 2-m x 3-m flat plate is suspended in a room, and is subjected to air flow parallel to its surfaces along its 3-m-long side. The free stream temperature and velocity of the air are 20oC and 7m/s. the total drag force acting on the plate is measured to be 0.86N. Determine the average heat transfer coefficient for the plate. Answer:h=12.7W/m2K
Properties of air at 300K(from my textbook
ρ=1.1763
c=1.007e03
μ=1.862e-05
v=1.5e-05
Pr=0.717
k=2.614e-02
Attempt at a solution
ReL=UL/v=7*3/1.5e-05=1.5e06 >5e05
xcr=(Recrv)/U=1.07
Nux,Laminar=0.332Pr1/3Rex1/2
Nux,Turbulent=(0.0296Re0.8Pr)/(1+2.11Rex-0.1(Pr-1))
Avg heat coeff
=(1/L){0∫xcrhx, Laminardx + xcr∫3hx, Turbulentdx}
= (1/L){0∫xcrNux, Laminar(k/x)dx + xcr∫3Nux, Turbulent(k/x)dx}
= ...
=14.39
I did approximate 1+2.11Rex-0.1(Pr-1) to be equal to 1 in my working because I didn't know how to integrate it. Is that acceptable? And I don't know how to use the drag force provided in this question. :x
I've been pondering over this question for a few days and I still can't get the answer please help check if my approach is correct. Thank you.
Properties of air at 300K(from my textbook
ρ=1.1763
c=1.007e03
μ=1.862e-05
v=1.5e-05
Pr=0.717
k=2.614e-02
Attempt at a solution
ReL=UL/v=7*3/1.5e-05=1.5e06 >5e05
xcr=(Recrv)/U=1.07
Nux,Laminar=0.332Pr1/3Rex1/2
Nux,Turbulent=(0.0296Re0.8Pr)/(1+2.11Rex-0.1(Pr-1))
Avg heat coeff
=(1/L){0∫xcrhx, Laminardx + xcr∫3hx, Turbulentdx}
= (1/L){0∫xcrNux, Laminar(k/x)dx + xcr∫3Nux, Turbulent(k/x)dx}
= ...
=14.39
I did approximate 1+2.11Rex-0.1(Pr-1) to be equal to 1 in my working because I didn't know how to integrate it. Is that acceptable? And I don't know how to use the drag force provided in this question. :x
I've been pondering over this question for a few days and I still can't get the answer please help check if my approach is correct. Thank you.