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Flashcards in L_2 Deck (14):
1

At high temperatures, gas becomes _____ ______.

chemically reacting

2

At high temperatures, air ratio of specific heats no longer equals ___, and is not _____.

1.4

constant

3

What creates the high temperature shock layer?

Flow kinetic energy is converted to internal energy of the gas across the strong bow shock wave

4

Gas behavior downstream of the nose region

The shock layer gas expands and is cooled around the body.

The Mach number is still high, and the hypersonic boundary layer can become chemically reacting.

(Note that blunt re-entry vehicles like the Shuttle have low Mach boundary layers on windward side)

5

For air, what are the principle ionized species?

NO+, O+ and N+

(along with associated free electrons)

6

For air at 1 atm, what happens around these temperatures:

800 K

2,000 K

4,000 K

9,000 K

>9,000 K

800 K: vibrational energy of the molecules becomes significant

2,000 K: dissociation of oxygen begins

4,000 K: O2 dissociation essentially complete, N2 begins to dissociate

9,000 K: most of N2 is dissociated

>9,000 K: partially ionized plasma, O, O+, N, N+, e-

7

Equation for heat flux towards a vehicle

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8

total enthalpy equation

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9

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10

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11

For high speed flight, heat flux towards the wall is ____ proportional to the atmospheric density and goes as the ____ of the velocity.

linear

cube

 

 

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12

Heat flux towards the wall is not heat flux into the wall.

How much heat flux gets into the wall is governed by the _____ _____.

Stanton number

13

What is the Stanton number equation?

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14

Approximate equation for heat flux into wall at high speeds

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