Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.
-
Upload
margaretmargaret-sanders -
Category
Documents
-
view
220 -
download
0
Transcript of Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.
![Page 1: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/1.jpg)
Heat Transfer and Fluid Heat Transfer and Fluid Flow Over a Flat PlateFlow Over a Flat Plate
MANE 4020Fall 2005
![Page 2: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/2.jpg)
(x)
U0
U(y)
U
xo
U(x,0)=0
Boundary layer thickness: yU(y)/ U =0.99
Fluid Problem: Friction and Fluid Problem: Friction and Boundary layerBoundary layer
s u
yy0
Shear stress
![Page 3: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/3.jpg)
Measurement of the Velocity ProfileMeasurement of the Velocity Profile
ptotal pstatic1
2 U2
U
![Page 4: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/4.jpg)
Laminar flow
Turbulent flow
Skin Friction CoefficientSkin Friction Coefficient
C f s
12 U
2
C f
2
0.332
Rex1/ 2
C f
2
0.0296
Rex1/ 5
Re x U x
Skin Friction Correlations
Skin Friction Measurement
s u
yy0
From: (difficult to get u near to wall)
![Page 5: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/5.jpg)
Boundary layer modelsBoundary layer models
71
y
U
u
u y
u 1
ln y B
y yu u u u ; u s
y+ 30
y+ 5
1/7th Power Law
More exact expression
![Page 6: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/6.jpg)
Boundary layer modelsBoundary layer models
![Page 7: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/7.jpg)
Convection Heat TransferConvection Heat Transfer
It quantifies the energy transfer between a fluid at one temperature flowing over a solid object at a different temperature.
h q
T
q
AT- q” is the heat flux (J/s m2 = W/m2)T is the difference between fluid temperature (in the freestream) and the solid wall temperature-A is the surface area of the solid. -q is the total heat transfer from a surface (Watts).
![Page 8: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/8.jpg)
Two common questions of any Two common questions of any convective heat transfer problemconvective heat transfer problem
Given the distribution of surface temperature as a function of position along a surface, what is the distribution of local heat flux?
Given the distribution of local surface heat flux as a function of position along a surface, what is the
distribution of surface temperature? Tfluid
Tsolid
![Page 9: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/9.jpg)
Fluid flow and heat transfer over Fluid flow and heat transfer over flat plate - A complex problemflat plate - A complex problem
(x)
U0 , T0
U(x,y) Tw (x)
T (x)U (x)
(x)
T(x,y)
xo qw qw qw qw
U(x,0)=0 Tw>Tinf
Rex= U *x/is the criterion for the Turbulent/LaminarRex>105 for the flat plate flowRed >2300, for the pipe flow
![Page 10: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/10.jpg)
Stx h
cpUfunc
Ux
,
h is the property of flow Pr is the property of fluid
Stx 0.453Re x0.5 Pr 2/ 3
Stx 0.0307Re x0.2 Pr 0.4
Laminar flow – can be derived
Turbulent flow - experimental
Dimensionless heat transfer Dimensionless heat transfer coefficient (Stanton #)coefficient (Stanton #)
![Page 11: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/11.jpg)
St decreases with the increase of Re.St increases when the flow becomes turbulent flow.
![Page 12: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/12.jpg)
Measurement of heat transfer Measurement of heat transfer coefficient (I)coefficient (I)
Q0
QconvectionQradiation
Qconduction
Qo Qconvection Qbackside Qradiation
![Page 13: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/13.jpg)
Tblack
TT
Tplate
Rconv
R rad
Rcond
Measurement of heat transfer Measurement of heat transfer coefficient (II)coefficient (II)
![Page 14: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/14.jpg)
The plate is constructed of four layers of materials:• Four, 2 in. wide Ni-Chrome heating strips which are embedded in
fiberglass and epoxy resin;• 3/8 in. balsa wood;
• 5/8 in. plywood;• 1/8 in. plywood.
![Page 15: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/15.jpg)
Qo Qconvection Qbackside Qradiation
Qo = VI Qconvection
Ts TR conv
hA(Ts T )
Qbackside Ts Tback
Rplate
44surrSradiation TTAQ
Tblack
TT
Tplate
Rconv R rad
Rcond
h
Measurement of heat transfer Measurement of heat transfer coefficient (III)coefficient (III)
![Page 16: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/16.jpg)
Structure of Wind TunnelStructure of Wind Tunnel
Wind supply: Blower /Fan (quantity supply); Settling chamber (quality supply)
Honeycomb, Mesh Screen To reduce turbulence
![Page 17: Heat Transfer and Fluid Flow Over a Flat Plate MANE 4020 Fall 2005.](https://reader035.fdocuments.in/reader035/viewer/2022062304/56649da85503460f94a942b3/html5/thumbnails/17.jpg)