Thermodynamic Cycle

Question 1

How can processes be classified with the 1st law of thermodynamics?

Answer 1

𝑤 ≠ 0, work transfer
𝑤 = 0, fluidic process
𝑞 ≠ 0, diabatic process
𝑞 = 0, adiabatic process

Question 2

What is stagnation pressure?

Answer 2

Sum of static and dynamic pressure

Question 3

What are the assumptions for an adiabatic (no work input), loss-free process?

Answer 3

𝑞1→2 = 0
𝑤1→2 = 0
𝑝𝑡,1 = 𝑝𝑡,2
Π1→2 = 𝑝𝑡,2/𝑝𝑡,1 = 1
∆ℎ𝑡 = 0
Δ𝑠 = 0

Question 4

What are the assumptions for an adiabatic (no work input) process with losses?

Answer 4

𝑞1→2 = 0
𝑤1→2 = 0
𝑝𝑡,1 > 𝑝𝑡,2
Π1→2 = 𝑝𝑡,2/𝑝𝑡,1 < 1
∆ℎ𝑡 = 0
Δ𝑠 > 0

Question 5

What is the standardised station identification?

Answer 5

0 - Ambient condition upstream
1 - Smallest area intake
2 - Entry to 1st compressor stage
3 - Exit HP compressor
4 - Entry HP turbine
5 - Exit of last turbine stage
6 - Entry afterburner
7 - Entry inner nozzle
8 - Smalles area inner nozzle
9 - Exit inner nozzle

Question 6

What is the standardised station identification extended for bypass?

Answer 6

12 - Entry Fan, Outer Portion
13 - Exit Fan, Outer Portion
18 - Entry outer nozzle
19 - Exit outer nozzle

Question 7

What are the assumptions for the ideal Joule-Brayton Cycle?

Answer 7

• Constant massflow through all components in the cycle
• Constant gas properties and gas mix across whole cycle, and constant specific heat
  capacity across the whole cycle
• Adiabatic compression (C) and expansion (E)
• No losses in components, isobaric combustion

Question 8

What are the steps in the Joule-Brayton Cycle?

Answer 8

• 0 –> t3 isentropic Compression: 𝑑𝑠 = 0, 𝑑𝑝 > 0
• t3 –> t4 isobaric Heat Addition:
  𝑑𝑠 > 0, 𝑑𝑝 = 0
• t4 –> 9 isentropic Expansion:
  𝑑𝑠 = 0, 𝑑𝑝 < 0
• 9 –> 0 isobaric Heat Removal:
  𝑑𝑠 < 0, 𝑑𝑝 = 0

Question 9

Where are pressure and temperature values maximum in a jet engine?

Answer 9

After combustion chamber, before turbine