The impeller chamber includes {HEAD ~ a variable area} wherein a first cross sectional area is defined between the radially outer surface and the first portion, and {TAIL ~ a second cross sectional area} is defined downstream from the first cross sectional area 
wherein
The impeller chamber includes { HEAD ~ a variable area } wherein a first cross sectional area is defined between the radially outer surface and the first portion , and { TAIL ~ a second cross sectional area } is defined downstream from the first cross sectional area
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH