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A modern jet engine has a temperature after combustion of
Chapter 4, Problem 124HP(choose chapter or problem)
Problem 124HP
A modern jet engine has a temperature after combustion of about 1500 K at 3200 kPa as it enters the turbine section (see state 3, Fig. P4.124). The com pressor inlet is at 80 kPa, 260 K (state 1) and the outlet (state 2) is at 3300 kPa, 780 K; the turbine outlet (state 4) into the nozzle is at 400 kPa, 900 K and the nozzle exit (state 5) is at 80 kPa, 640 K. Neglect any heat transfer and neglect kinetic energy except out of the nozzle. Find the compressor and turbine specific work terms and the nozzle exit velocity.
FIGURE P4.124
Questions & Answers
QUESTION:
Problem 124HP
A modern jet engine has a temperature after combustion of about 1500 K at 3200 kPa as it enters the turbine section (see state 3, Fig. P4.124). The com pressor inlet is at 80 kPa, 260 K (state 1) and the outlet (state 2) is at 3300 kPa, 780 K; the turbine outlet (state 4) into the nozzle is at 400 kPa, 900 K and the nozzle exit (state 5) is at 80 kPa, 640 K. Neglect any heat transfer and neglect kinetic energy except out of the nozzle. Find the compressor and turbine specific work terms and the nozzle exit velocity.
FIGURE P4.124
ANSWER:
Solution 124 HP
Step 1 of 3
We have to find the compressor and turbine specific work terms and the nozzle exit velocity.
The Enthalpy of air at different states can be found from the Table A.7.1
State
At 260 K and 80 kPa
State At 780 K and 3300 kPa
State 3 At 1500 K and 3200 kPa
State At 900 K and 400 kPa
State At 640 K and 80 kPa
The compressor specific work term can be found using steady state single flow energy equation neglecting heat transfer and kinetic energy.
Where,
kJ/kg
kJ/kg
Thus,