Surface temperature profile of a forced convection in circular tube

[MechaMZ]

Hi,

I've did an experiment today, a forced convection in circular tube where the heat flux is constant along the length.

my result seems not follow what it should be..

[PLAIN]http://img688.imageshack.us/img688/8015/expresult.png

what I'm wondering is shouldn't it in a fully developed region, the surface temperature Ts will also increase linearly in the flow direction. but why my surface temperature at the left hand side is increasing until certain point then decreasing along the way to the outlet?

am i right to say because the outlet is not sealed? so it affect the Re and then disturb the heat flux? please correct my assumption if it is wrong.

 

[MechaMZ]

exit and entrance effects?

 

[TOONCES]

how long is the pipe and how is the heat being applied?

 

[MechaMZ]

it is about 2 meter in length