{HEAD ~ The swirling stream} of {TAIL ~ air} circulates about the common axis of the nozzles 20, 30 and centering surfaces 25, 34 
of
{ HEAD ~ The swirling stream } of { TAIL ~ air } circulates about the common axis of the nozzles 20 , 30 and centering surfaces 25 , 34
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH