When I face a Sentinel with Ryu, I try to use hadoukens whenever I can.
To get close to him, super jump and BLOCK. Dont attempt to hit him, unless you know he won’t use his launcher.
When you get close, he will probably do 2M and launcher. I think there is enough time to dash and 2M, 5C etc
If you are too close, jA works as an overhead, so you can combo after that.
When he flies and hit you with jC, I do believe you can Shoryuken him before his jS comes out.
Airborne Shinkuu Hadouken is your best friend, and using medium and fierce tatsus can trap him into hitting the air, allowing you to Shinkuu Hadouken him.
When they are too far away, they usually use his beam and cancel it into small flying robots. If you can predict that (Its not hard), you can Shinkuu Hadouken him before he shoots his beam.
I’ve got a few combos for Ryu on this vid, and there is a small loop on a cornered Sentinel:
I hope it helps.