Effects of venturi length on combustion characteristics of inshot burners

An experimental study of the changes caused in the flame structure and pollutant emission characteristics by the modifications to the primary-air venturi of an inshot burner used in residential natural gas furnaces is presented. The venturi modification examined in this study are the shape of the venturi inlet and the venturi length. Modified venturis with curved inlets produce higher primary-air entrainment and slightly smaller (by 5 to 10%) emission indices of NO/sub x/ and CO than the standard parallel side venturi. However, the changes in the venturi length for the modified geometry do not result in significant further changes.