I am just another one of the passionate flight simmers trying to understand more about Anti-ice system mechanics. I am talking about the Boeing 737-800 here if it makes a difference.
What bothers me is: Why is turning on TAI systems having negative impact on descent performance? Given a constant speed that we want to keep a shallower descents can be experienced.
Let's imagine a descent with thrust levers in IDLE position. From my research about aircraft systems and jet engines I would assume that turning on TAI would (in that order):
get more bleed air -> less air to burn -> turbine turning slower -> decreased N1
But from what I can experience and read on the web N1 is actually increased instead. I can guess the aircraft it trying to compensate something - but what is it if we're in idle descent? Also, I am assuming the decreased vertical speed comes from somehow increased thrust, which I would also suspect to be lower (or at least kept on the same level as before TAI) not higher than originally.
I understand this is a complex system and each part has impact on each other but maybe you can point me in the right direction ;)