Wear on bucket tips in steam turbines is definitely an issue, but that’s on the low pressure section where you have two things (tall buckets = high tip speeds) and most importantly the steam expansion takes place in the Wilson region where you can have 1-15% moisture depending on exhaust backpressure (and the type of exhaust on the Camaro that rolls by if you are female- but I digress).
The last stage in almost any power generation steam turbine is designed to operate with tip speeds beyond supersonic. Just a function of how large the blade size is since speed is pretty much constant (3600 RPM for 60 Hz markets like the US). The issue is preventing the moisture droplets from wearing the buckets on the inlet side.
Couple countermeasures to this- these include welding hardened stellite to the inlet edge of the blade as well as grooves on some inlet edges to allow the moisture to ride up the groove (from centrifugal force) and then eject outwards. Corresponding drainage grooves are built into the inner casing as well to allow the moisture to exit and go into the condenser.
At the front side (high pressure) end of a steam turbine you will have another kind of erosion but this comes from exfoliation of oxidized scale in the piping from the boiler.
But as you alluded to, the relatively tiny size of the microturbines and controlled operating environment means they aren’t prone to these (and many other) types of issues.
Given the small size I can’t see why the stationary portion (nozzles) on the microturbines can’t be controlled to alter angle and improve efficiency over a range of operating parameters. Something that size, startup and light off shouldn’t take ages, but yeah I’m sure it will require development!
definitely hit the mark here. you’ve got a bit more knowledge on the subject that i do. some crazy high tech stuff that goes into these, and even now on the gas turbines where the buckets have hollows and micro holes where they pump cooling gas through them to keep the leading and trailing edges from vaporizing at the insane temps they run. I was at GE years ago during a convention with my father and got to see the machining of some of the buckets. nutty stuff, and that was 15 years ago!
all agreed, especially on that last statement you made would be very similar to a VNT turbocharger, and could overcome a majority of the turbines major faults in this application. If they coupled this with some new tech to keep rotating mass down having a “throttled” micro turbine would be very possible.
I’d LOVE to see this happen. Just the ability ot say i have a turbine powered car in the stable is good enough for me to buy it :number1