In some exemplary embodiments, the control conduit may comprise a gas passage proximate {HEAD ~ the entrainment passage} to allow {TAIL ~ the control gas} to flow across the entrainment passage 
to allow
In some exemplary embodiments , the control conduit may comprise a gas passage proximate { HEAD ~ the entrainment passage } to allow { TAIL ~ the control gas } to flow across the entrainment passage
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH