at least one stage of {HEAD ~ a second turbine impeller} affixed to the rotating shaft that extends through the second turbine impeller, {TAIL ~ the second turbine impeller} being arranged downstream of the first turbine impeller, 
at least one stage of { HEAD ~ a second turbine impeller } affixed to the rotating shaft that extends through the second turbine impeller , { TAIL ~ the second turbine impeller } being arranged downstream of the first turbine impeller ,
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH