Calculating Heat of Object in Re-Entry: Kelvin °

[nicholas0211510]

How do scientists calculate or estimate the heat of a object in atmospheric re-entry in ° kelvin (the specific formula or formulas if any exist). I'm guessing it has to do with velocity and mass of the object but I'm not sure on the whole process

Thanks in advanced :)

 

[phinds]

I don't have an answer to your question, but just FYI "reentry" is a term only used for stuff that we sent up and are getting back (whether we like it or not). Meteors have never been here so they are not RE-entering, just entering. Also, I think the heat you are talking about is just what exists at the surface of the object entering the atmosphere. For example, the Space Shuttle ablative tiles got REALLY hot, but the rest of the vehicle didn't. So "meteor heat" isn't quite the right concept, it's more "surface heat of object entering atmosphere".

phinds the NitPicker

 

[nicholas0211510]

Thanks for some clarification :)

 

[Murdock]

Disclaimer: I may not know what I'm talking about. I would appreciate it if someone more knowledgeable than I could correct any errors.

I recall reading somewhere, I have no idea where, that the majority of heat comes from, compression, rather than friction. I would imagine that the heating from friction would pretty well cancel out with how quickly the air would cool it.

If that is correct, you should be able to determine the temperature of the air if you can calculate the pressure in front of the object.

 

[Andy Resnick]

How do scientists calculate or estimate the heat of a object in atmospheric re-entry in ° kelvin (the specific formula or formulas if any exist). I'm guessing it has to do with velocity and mass of the object but I'm not sure on the whole process

Thanks in advanced :)

You can get a rough estimate by the color of the meteor trail (assuming blackbody radiation and using Wien's law)- by my eye, the color is orange-red, corresponding to about 5000K. The space shuttle materials, during re-entry, had to deal with about 2000K loads

 

[256bits]

Disclaimer: I may not know what I'm talking about. I would appreciate it if someone more knowledgeable than I could correct any errors.

I recall reading somewhere, I have no idea where, that the majority of heat comes from, compression, rather than friction. I would imagine that the heating from friction would pretty well cancel out with how quickly the air would cool it.

If that is correct, you should be able to determine the temperature of the air if you can calculate the pressure in front of the object.

Stagnation temperature.
Nasa has a brief on it.
http://www.grc.nasa.gov/WWW/BGH/stagtmp.html

The graph gives temperature in degrees Rankine.

The dotted lines for an imperfect gas means that the object( or the air) has to be traveling faster to give the same stagnation temperature, or, at the same Mach number the imperfect gas will give a lower stagnation temperature.

Of course that temperature is only at one small spot where the air and the object are at the same velocity relative to one other, hense the term stagnation.