Step 3: To enhance combustion performance such as NOx reduction,
combustion efficiency, and flame-back prevention. under the
same heat input condition, the fuel injection port is designed to
meet the following conditions I, II and III. The same heat input
can be accomplished by adjusting the diameter of the fuel injection
port to the resultant value obtained in the second step, but the
experimental results showed increased NOx concentration and reduced
combustion efficiency. To complement these results, the
number of fuel injection ports is increased to enhance the fuel–
air mixing and the fuel injection ports are positioned uniformly
in upper and lower streams. Consequently, the combustion efficiency
can be increased through flash-back prevention and improved
mixedness of fuel and air.