L_1

Question 1

Hypersonic flight, usual definition

Answer 1

Question 2

Are real gas effects important for hypersonic flight?

Answer 2

Yes

Question 3

Thermally perfect gas equation

Answer 3

Question 4

calorically perfect gas meaning

Answer 4

constant specific heats c_p and c_v

Question 5

Can a gas be thermally perfect but calorically imperfect?

Answer 5

Yes

Air in many aerothermodynamic problems is treated as thermally perfect but calorically imperfect

Question 6

“Real gas” effects in aerothermodynamics are usually …..

Answer 6

high temperature real-gas effects

Question 7

Classical real gas

Answer 7

van der Waals gas

molecular spacing comparable to range of intermolecular forces (e.g. low temperatures and high pressures)

Question 8

real gas factor Z definition

Answer 8

Question 9

virial coefficients equation

Answer 9

Question 10

air real gas factor maximum value above room temperature for 100 atm

Answer 10

about 1.04

Question 11

specific heat ratio of air for all pressures and temperature of 1500 K

approximate specific heat ratio of air for 100 atm and room temperature

Answer 11

about 1.30

about 1.55

Question 12

For a hypersonic free stream, are these parameters small or large?

velocity

pressure

density

temperature

van der Waals effects

Answer 12

large velocity

small pressure

small density

small temperature

small van der Waals effects (due to small temperatures and small pressures/density)

(neglect van der Waals effects in hypersonic flight)

Question 13

For a hypersonic stagnation area, are these parameters large or small?

velocity

pressure

density

temperature

van der Walls effects

Answer 13

small velocity

large pressure

large density

large temperature

small van der Waals effects (due to large temperatures and large pressures/density)

(neglect van der Waals effects in hypersonic flight)

Question 14

Neglect van der Waals effects in ground test facilities?

Answer 14

Not always, due to high reservoir pressures/enthalpy

Question 15

Internal energy of a molecule

Answer 15

Question 16

characteristic rotational temperatures of N₂, O₂, and NO

Answer 16

Rotational energy is fully present at very low temperatures.

Question 17

For lower hypersonic flight speeds, how is e_electronic treated?

Answer 17

e_electronic is treated as unchanging (neglected)

Question 18

high temperature real gas effects of interest

Answer 18

vibrational excitation

dissociation/recombination