How is combustion directed in one direction in a jet engine?
The shape of combustion chamber does the trick. It's expanding towards the turbine. Pressure is highest when the air leaves the last compressor disk. Fuel is added to keep pressure from dropping. The pressure it's just a bit lower but the amount and temperature of the air is much greater so the air can be used to turn turbine. To increase efficiency pressure drop is kept to minimum. If something wrong happens or throttle is advanced very fast compressor blades can be effected. The surge happens and flow direction reverses.
Look at the cutout picture of a real jet engine. It will be obvious. There are very simplified pictures of the jet engine that can make understanding confusing as they can be just wrong.