Quote:
Originally posted by rdorman
Anyways, so the rotor acts main method of ridding the system of heat? In the most simplistic terms the rotor, by design and relationship to the air flow, cools faster and as the temperatures between the rotor and pad attempt to equalize thermal energy is transfered to the rotor and then disappated? Some where in the ball park?
Rick
|
Rick,
Correct. We always simply treat the rotor as a heat storage device.
You know, rate of input and rate of exchange to atmosphere. (Of course atmosphere is a really tricky bit. As moisture content is quite critical in the calculation. Think about water spray systems in Trans-Am cars.)
The caliper is ignored as a part of the heat exchange system.
The pad is considered from its CF and ablative exchange characteristics.
Blykins,
Correct assumptions. The more rotor mass, the more heat one can store per braking event.
However, heat transfer area of rotors is quite dependent on configuration of the rotor and the air supply system to it.
A solid rotor is of course the simplest unit to calculate. Vented units are very difficult due to the various configurations of the internals. The internal vane area needs to be calculated and of course the rate of transfer from the input surface to the interior, etc. (IE: heat path.)
This now this gets really confusing as the air supply system to the center of the rotor becomes very important as well as the wheel configuration. The vented rotor is typically treated as a headed centrifugal pump in a confined system.
We find it best to just look at rotor mass in the equations and leave the rest to empirical data and adjust the systems from there.
Rick said,
"That seems logical to me. Is it fair to assume that the drop in temperature of the rotor will be closely followed by the pad temperature? This may already be explained in the formulas but I have yet to digest them."
Close enough for government work.
But this is where ablation and material heat transfer rates come into the mix. The pad temps are seldom equal to rotor temp until you reach ambient levels. Remember that rate of exchange is wildly different for pad materials, whereas iron is pretty constant. Plus pads do not contact the rotor once pressure is removed from the system. The O-Rings pull the pads away from the rotor in a properly designed caliper.
Threaded Mode
