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