Engine Net Thrust vs engine anti-ice.
I would like that someone could explain me the reason why the airflow entering the engine is lower when engine anti-ice is switch ON.
Quoted from PW data refering JT8D-219 engines:
" In the procedure for calculating net thrust, the increased fuel flow required for ice protection is included in the calculation of gas flow through the nozzle. The fuel flow increase CAUSE THE AIRFLOW TO BE LOWER than that without ice protection. The ram drag is therefore less and the net thrust is higher than the no ice protection case"
Inlet air flow decreases from 529 lb/sec to 523, and so Ram drag goes from 5421 to 5392, therefore net engine thrust increases from 17480 to 17542, gross engine thrust remaining the same.