Heat on heat shield. Friction or compression?

Click For Summary
SUMMARY

The discussion clarifies the mechanisms of heat generation during the reentry of vehicles, emphasizing that the majority of heat is produced through atmospheric compression rather than friction. Experts from NASA indicate that approximately 90% of the heat results from compression, while about 10% is attributed to viscous dissipation, commonly referred to as friction. The concept of recovery temperature is introduced, highlighting the difference between stagnation temperature and the actual temperature experienced by the surface of the heat shield. This nuanced understanding is essential for those studying atmospheric heating and reentry vehicle design.

PREREQUISITES
  • Understanding of atmospheric heating concepts
  • Familiarity with fluid dynamics principles
  • Knowledge of heat transfer mechanisms
  • Basic grasp of reentry vehicle design
NEXT STEPS
  • Research "reentry vehicle thermal protection systems"
  • Study "viscous dissipation in fluid dynamics"
  • Explore "recovery temperature in aerospace engineering"
  • Learn about "stagnation temperature and its implications"
USEFUL FOR

Aerospace engineers, thermal protection system designers, and students of fluid dynamics interested in the physics of reentry vehicles and atmospheric heating mechanisms.

thenewmans
Messages
168
Reaction score
1
I always thought of a reentry vehicle compressing the air in front of it. And that would cause a lot of heat kind of like filling my tires. But I keep hearing friction even from NASA heat shield experts. OK, I guess maybe 10% of the heat is friction. I always assumed they said that to make the concept easier. But I’ve heard it so much recently that I’m starting to think I’m wrong. Or maybe they’re the same thing in a way that I hadn’t understood yet. Can you straiten me out?
 
Engineering news on Phys.org
The jargon is atmospheric heating, and its explanation is
When fluid flow slows down its kinetic energyis converted to heat; in high speed flows, tremendous energy is represented by the mean motion of the flow. As the flow is slowed to near zero speed, its temperature increases, the gradient in the speed in a direction normal to the surface allows small scale mass transport effects to dissipate the temperature in the outward direction and thus the temperature at the surface is less than the stagnation temperature; the actual temperature is referred to as the recovery temperature. [ ... ]
I am a sustaining contributor to The Wikimedia Foundation
 
Both are contributors. The heat is mostly generated through the compression but there is some that comes from viscous dissipation as well (or what you might call "friction"). The "friction" plays a great role in transferring that heat to the surface, however.
 
That's what I love about PF. Thanks guys. I did found some good stuff on "viscous dissipation"
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
5K
  • · Replies 20 ·
Replies
20
Views
5K
  • · Replies 10 ·
Replies
10
Views
4K
Replies
1
Views
2K
Replies
14
Views
5K
  • · Replies 82 ·
3
Replies
82
Views
28K
Replies
37
Views
14K
  • · Replies 3 ·
Replies
3
Views
6K