Chapter 6. Turbofan engine with afterburner

Similar to the turbojet engine, the afterburner can be installed in the turbofan engine to increase the maximal thrust. Usually the turbofan engine with afterburner has a mixing chamber and afterburner after it (Fig. 6.1).

Fig. 6.1. Scheme of turbofan engine with afterburner.

The calculation of turbofan engine with afterburner is similar to turbofan engine for the section up to afterburner and to turbojet with afterburner for the section after afterburner.

4. The total pressure after turbine is

and the total temperature is

4 (mix). The pressure at entrance of mixing chamber from internal contour is

The total pressure at the entrance of mixing chamber from external contour is

and the total temperature is

The normalized gas speed at the entrance of mixing chamber from external contour can be find based from condition that static pressure is equal for internal and external contour exit :

The total temperature of mixed gas is

and the total pressure at the mixing chamber exit is

4 (ab). The total pressure after afterburner is

The relative fuel consumption in the afterburner is

where the enthalpies   and   can be found from the empirical curves [1].

5. If the pressure is fully discharged in the nozzle the normalized gas speed from nozzle is

6. The specific thrust is

and the specific fuel consumption is

The thrust is

7. The effective efficiency of cycle is

where  is an effective work of cycle that can be found from

The flying efficiency is

The total efficiency is