I have seen quite a few tutorials on how to attack a ship/convoy, but I haven't found anything regarding the escape

If there is, please accept my apologies for the useless post
If there is not, how is everyone doing once the attack has been launched and the torpedoes have hit the target ?
I thought about just diving at 150 all stop, silent running. I think it might work, well it actually worked once but I'm not sure if it works often enough to be considered as a valid escape tactic.
I'm wondering, if you are spotted, how do you know if an escort has you on asdic or sonar ? Is hearing them increase their speed the only way to guess that you have been found ? And how can you escape their asdic or sonar once you have been spotted ? I have trouble with this.
And when depth charge are falling on you, what's the best option ? I have used the automated scripts, but it goes ahead flank and i'm sure they can then locate me even more precisely.
Although it is surely better to be detected and stay alive than die
I have spent 2 hours trying to evade 4 escorts with no luck, and I'm trying to figure out what I could have done.
I know it's a lot of questions at once, but if I could get some hints, that would be great
Ps: I'm using IRAI from tdw, default settings.