Moving Platform and Heat Transfer Calculations
Moving Platform and Heat Transfer Calculations
(OP)
Hi. I am a newbie here. I have a moving platform. At first it is at rest. Then it accelerates with 1.230 m/s sq. and reaches 17.2 m/s speed in 14s. The distance it takes in this period is 120m. Then, with the constant pace it keeps its motion 18s. Then it begins to decelerate and stops in 8s. I need to find heat loss occurs on the panels of the platform. I have a theoretical background about heat transfer. However as I told it is a moving platform, i do not know actually which parameters should i take into consideration. I know, i need to focus on convection but what changes the motion of platform related with calculations.





RE: Moving Platform and Heat Transfer Calculations
RE: Moving Platform and Heat Transfer Calculations
I would take a stab and say that the velocity of your fluid would be the same as the velocity of the platform and then you can do a force convection solution. And, for the platform at rest, it would be a flat plate (horizontal or vertical depending on you orientation) natural convections solution.
Tobalcane
"If you avoid failure, you also avoid success."
RE: Moving Platform and Heat Transfer Calculations
RE: Moving Platform and Heat Transfer Calculations
From your description, there is never a period of natural convection, since you always have a constant 11.11 m/s absolute wind velocity.
However, the more germane question is what does this really matter? A total period of 40 seconds is only of importance if your object's thermal mass is on the order of a few sheets of paper or exceedingly small. Is that the case?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Moving Platform and Heat Transfer Calculations
kvnccelik, are you trying to find Watts (heat rate) or Jouls (quantity of heat)?
Tobalcane
"If you avoid failure, you also avoid success."
RE: Moving Platform and Heat Transfer Calculations
Consider lumped mass m, moving in direction s, with velocity u.
With no internal heat generation, an energy balance is:
mCv(dT/dt+udT/ds)=hA(To-T) Where Cv is specific heat, h the local heat trans coef, T temp, To surroundings and t, time.
RE: Moving Platform and Heat Transfer Calculations
RE: Moving Platform and Heat Transfer Calculations
Tobalcane
"If you avoid failure, you also avoid success."
RE: Moving Platform and Heat Transfer Calculations
A 2.3m x 2.3m object sounds suspiciously like the canonical NATO tank. It's thermal mass is so large that a 40 second test will do little to affect its overall temperature.
The M4 Sherman from WWII weighed in at nearly 30 USCU tons. Assuming all steel, it has a thermal mass of 15MJ/K. If we assume 20W/m^2-K heat transfer coefficient and 5*(2.3m)^2 surface area, the thermal time constant is about 8 hrs, so a 40 second exposure to wind will perhaps cool the paint a bit, but not much else.
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Moving Platform and Heat Transfer Calculations
Tobalcane
"If you avoid failure, you also avoid success."
RE: Moving Platform and Heat Transfer Calculations