PROBLEM 1 Turbojet Cycle Analysis

In the turbojet lab, a model aircraft engine operates on a pure turbojet cycle as illustrated in Fig. 1. The turbojet does not have a diffuser. The pressure ratio of the compressor, P2/P1, is a function of the engine speed, Ω, as expressed as

Table 1 lists the test conditions and air and fuel properties. Use the data collected in Table 2 and answer the following questions.

1. Draw the T-s diagram of the cycle.

2. Conduct an ideal cycle analysis for the turbojet. Derive the equation to determine the following parameters using the data in Table 2

2a. the turbine-inlet temperature, T3

2b. the exhaust velocity, v5

2c. the air flow rate

Note: Do not use the measured thrust for the analysis as it is a practical output.

3. Plot T3 and v5 vs. engine speed from the analysis in Part 2.

4. Compare the exhaust velocities, v5, with the speed of sound at the standard condition and discuss the results. Note that the engine is not designed to produce supersonic flow.

5. Calculate the thrust produced by the ideal turbojet cycle. Plot the calculated and measured thrusts vs. engine speed on one graph.

6. Discuss what caused the difference between the calculated and measured thrusts.

7. Calculate the ideal cycle thermal efficiency (ratio of the useful output and the required input). Plot it against engine speed.

8. Determine the temperature and pressure at state 1 to 5, report them in a summary table for all engine speeds.