It’s the fuel flow, not so much engine life, that is the major drawback of augmentors/afterburners. The core hardly notices whether the augmentor is in operation or not, but everything aft of it does, especially the nozzle. Added heat, loads, vibration, and thermal cycles. The fuel flow though, is astronomical, much more than the core’s fuel flow. Of course the other issue is that augmented commercial engines are not currently in production, and the standards military engines are designed to are not suitable for certified commercial use. Stress margins and lifing requirements, for instance, are more rigorous for commercial engines.
Doesn’t the core have to work harder?
Not in a properly designed engine. Just as in the core combustors, fuel burning creates increased volume that is converted to velocity by the divergent nozzle, with no pressure rise. The highest pressure still is just past the last stage of the HP compressor.
Absolutely right AJ. If airliners flew 30-50 Kts slower due to a comfortable, wide cabin with decent seats and good legroom there would be a good market as the flight would now be something to anticipate in good terms and not in a horrendous prospect of several hours of overcrowding and crammed seating. This wonderful idea of supersonic passenger travel is so long past public acceptance that any corporation that enters the public domain will be socially tarred and feathered together with their corporate profile. A really bad avenue to follow in social, political and economic terms.
Not necessarily, in modern engines, but the engineering answer is always “it depends”. There are different power ratings in and out of augmentor operation and different core conditions to suit. Maximum continuous, maximum (duration limited), maximum with no augmentor… however named all would be defined by the manufacturer. At a duration limited or overall maximum power setting you would necessarily see higher core (typically Turbine Inlet Temperature is the limiting factor) temperatures than at continuous power, even if the engine speeds are the same, so that would be the core “working harder” in afterburner, but that condition of working harder is not necessary for all augmentor operation. Typically there will be a minimum engine speed required for augmentor operation which depends on the operating conditions but the EPR and temperatures would be managed by the engine control systems using fuel flow schedules, nozzle geometry, bleed control, bypass ratio control. There’s a lot at play. The root result is the same though, with augmentor in operation specific fuel consumption will skyrocket, so if you can go supersonic without it, that is always going to be preferable.