fig6 the downstream ends 72 of the nested members employed in flow divider 70 are preferably flared i e curved shaped flanged or otherwise directed outwardly so as to intersect the lateral sidewall openings 62 provided around the downstream end portion of burner pipe 61 thus dividing each of the openings 62 into a plurality of opening sections by way of example flow divider 70 is shown as having two nested members 76 and 78 each of which includes a curved flared downstream end 72 and 73 these curved flared downstream ends 72 and 73 intersect openings 62 and thereby divide each of openings 62 into a downstream opening section 64 an upstream opening section 66 and a midstream opening section 68 as shown in fig6 it will be understood by those skilled in the art that the number of opening sections created will increase as the number of nested members increases in the embodiment depicted in fig7 and 8 the flared downstream ends of the nested member can comprise for example a tapered surface 74 and or a perpendicular surface 73 as illustrated in fig9 another embodiment 80 of the present invention comprises a burner pipe 81 having a flow divider 90 preferably provided in the interior of burner pipe 81 adjacent the downstream end flow divider 90 preferably comprises a plurality.