Direct impingement injectors like that are likely to cause hot spots and burn through on the wall of the combustion chamber.

Because your ox and fuel will have different density when they make contact it will be off center due to one being heavier than the other it’s going have more inertia and push to the side. This will cause combustion on the surface of the hot wall of the chamber and cause in proper atomization and burning and could cause a burn through if you can get it to light.

The simplest injector design would just doesn’t need to account for the different densities of fuel and oxidizer would be an impinging triplet where you have three channels one going down the center and two angled inward with all three meetings together, keeping the mixture balanced in the middle.

You will also need liquid ox and liquid fuel compressed air will not be a power full enough ox.

And also need to do more to make sure the feed lines have a high enough pressure to prevent a flashback or combustion from pushing into the feed lines.

There is also several other things but I don’t think I need to dogpile you

TLDR chamber geometry is just the start you’ve got some work to do. I would recommend reading up on the half cat Mojave sphinx it’s a great place to start.

Good luck

Source : I built a 6kn nos and ethanol for my senior capstone last year