Which fuel nozzle type is most widely used and provides good spray characteristics under all operating conditions?

• A. Duplex type - most widely used, good spray characteristics under all operating conditions
• B. Simplex type - spray pattern with limited use
• C. Triple type - specialized for variable spray
• D. Quadruple type - high-pressure spray

Answer: (A)

Fuel nozzle performance across the engine’s operating range depends on how well the fuel is atomized and distributed into the combustion chamber. The duplex nozzle uses two spray orifices, providing two simultaneous spray patterns that together adapt to varying pressures and airflow. This dual action produces finer atomization and a more even fuel–air mix from idle through takeoff and cruise, making it the most versatile and widely used type. A simplex nozzle has a single spray pattern and is less adaptable, so its spray characteristics aren’t as reliable across all conditions. Triple and quadruple designs exist for more specialized spray control or higher-pressure needs, but they aren’t as broadly suitable for the full operating range.