Rotor Convection Coefficient

[NoodelT65]

Hello my name is Theo and I'm the brake lead for San Diego State University's car. I have done some calculations to predict the temperature of the rotors during endurance. I'm using the equations that predict convection coefficient and repeated braking temperature; found in Rudolf Limpert's book "Brake Design & Safety" 2nd edition. I have it setup for 70 braking applications from 45 to 0 mph at 1.6g with a convection coefficient of 40 W/m^2K. The rotors are reasonably sized ( cast iron, 653 grams) however the temperature after repeated braking is around 2200 K.

Is 40 a reasonable average value for convection at 45 mph ?

What values have others calculated or measured?

[Hector]

I've seen h values ranging from 20-100 W/(m^2*K) depending on vehicle speed, so your value seems in the ballpark. It may be silly to ask, but are you accounting for all 4 rotors? I have made this mistake more than once!

[MCoach]

That coefficient may be in the ballpark...but I wouldn't believe that temperature value for a second.

I would believe a 1/4 of that value for a single rotor though.

[Z]

I have done some calculations to predict the temperature of the rotors during endurance.
...
What values have others calculated or measured?

Noodel,

Try this "Brakes Revise" thread. Ten pages there covering a lot of what an FSAE brake guy might need to know (the more detailed brake temp calcs are towards the end).

Z