I found this illustration of a turbopump. I need to know if my intuitive sense is correct here. So, the turbine is located at the bottom right. The gas coming from the gas generator is fed into the torus shaped pipe on the left of the two turbine blades. First there is the HP turbine, the thin one. Then there's the LP turbine, the wide one. The exhaust then goes to a Laval nozzle or so to accelerate the rocket some more. Now, I notice that the opening is shaped just like a Laval nozzle. At first the gas coming from the pipe is compressed as the opening gets narrower. Then there appears to be a throat, where M=1. Now the opening diverges, and speeds up to make the turbine more efficient. Is all of this true?