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