Duplex burner with velocity-compensated mesh and thickness

A combustion system, comprising:

• a combustion chamber;
• a fuel and oxidant source oriented to emit fuel and oxidant into the combustion chamber;
• and
• a perforated reaction holder disposed in the combustion chamber and oriented to receive the fuel and the oxidant at an input face, the perforated reaction holder defining a plurality of perforations of different sizes, the perforations arranged by size to accommodate a combustion reaction substantially within each perforation when the fuel and the oxidant are received at different velocities across the input face of the perforated reaction holder.