Hi Prex and sailoday28,
I calculated the Biot number with (Cross Area)/(Perimeter) as the characteristic length. The Biot number is 0.07 << 1. Also, the fin is comparatively thin. So I can assume a one dimensional heat transfer.
Prex, I impose a temperature of 1200°C at the fin tip and...
Hi Prex,
This value is found from empirical results. The cylinder is rotating at 20000rpm. I assumed cosistent convective heat coeffient throughout the entire fin from tip to base because it is really very turbulent.
I dont understand the point about the fin being infinite. How did you...
Hi Prex and Sailoday28,
I organised my thoughts and came to the following conclusions. The only confirmed boundary condition is that the tip of the fin must be kept at 1200°C (at x=0 which is fin tip), heat input would cause the fin tip to rise to 1200°C and we have then a steady state...
The heat generation is applied so we know the volumetric heat genertion, and here I assumed 250W is generated in the fin. Btw, i know that the flux q at x=0 and the temperature at x=0, can i still solve the equation. I cannot assume anything at x=L because the fin is short, there is, I presume...
Hi Prex and IRstuff,
I guess I made a mistake in the flux. I guess that 250W of energy is generated in the tip of the fin. The volume of heat generation would be cross sectional area multiplied by the penetration depth which is about 1mm. However, the heat flux 250W/(1.5X15X10^-6) still...
Hi Prex,
I tried solving the fin equation but got erronous results. This is what I did.
T§ means the temperature of the air far away which is taken to be 30°C.
The equation of the fin is T-T§ = C1 sinh(mx) + C2 cosh(mx)
where C1 and C2 are constants to be found and m^2 = (hP)/(kA) where h...
Hi, in case I did not specify the problem properly, I written the problem including diagrams to the post. The link is here:
http://home.pacific.net.sg/~emailcs/Finproblem.pdf
I tried the general temperature equation of the fin but got erroneous results. I specified the tip temperature at...
The Rotational reynold number is pwD^2/(2u). p is the density of air, w is rotation speed, D is diameter, u is dynamic viscosity of air. The reference i mentioned should be sufficient for your problem, please check those out.
Hi,
I have a problem regarding the temperature distribution in a fin. The problem is different from the usual fin problem, instead of heat flowing from a body to the fin attached on it, there is heat generation at the fin tip and the heat transfer is actually to the environment through...
Hi, do you have cross flow or is the heat transfer in still air? You may like to check out the following references that you may find useful if the rotating drum is in still air:
T.Anderson and O.A. Saunders, Proc. Roy. Soc. A 217, 555, 1953
W.M. Kays and I.S. Bjorklund, Trans. ASME 80, 70...
I would also like to ask about the availability of the following articles of the earlier works in rotating disk:
E.C. Cobb and O.A Saunders,"Heat transfer from a rotating disc," Proc. Roy. Soc., Ser.A. Math. Phys. Sci. 236,343 (1956)
W.G. Cochran, "The flow due to a rotating disc," Proc...
Hi all,
Following a recent thread that I posted recently, I finally found a suitable model for my problem, that is a rotating disk model. However, I am looking for existing textbook and/or literature of heat transfer of a rotating rotor at high speed. Can any one of you recommend some good...
Thanks imok2 for the file, I have a similar doctorate dissertation but I thought if anyone has any correlation equation for rotating machines that I can apply quickly. I got some diagrams to clarify the poblem. It is at the below link.
http://home.pacific.net.sg/~emailcs/heat transfer...
I have a specific problem about the cooling rate of a blade attached to a rotor spining at 20000rpm. The blade would achieve a temperature of 1200°C after heating and I need to find the cooling rate of the blade tip and its final temperature after a single quarter revolution. Since the blade...
