In {TAIL ~ other embodiments}, {HEAD ~ the rows} 50 may be positioned generally orthogonal to a direction of an average flow of a gas 51 through the cavity 14 
In
In { TAIL ~ other embodiments } , { HEAD ~ the rows } 50 may be positioned generally orthogonal to a direction of an average flow of a gas 51 through the cavity 14
REL TAIL 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 OTH OTH OTH OTH OTH OTH OTH