In {TAIL ~ operation}, {HEAD ~ the gas} flows through the body 6 from the inlet end 7 in an axisymmetric profile 
In
In { TAIL ~ operation } , { HEAD ~ the gas } flows through the body 6 from the inlet end 7 in an axisymmetric profile
REL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH