What is the goal of using two discharge spray patterns in duplex fuel nozzles?

The use of two discharge spray patterns in duplex fuel nozzles primarily aims to improve combustion at different engine speeds. This dual spray system allows for the optimization of fuel delivery depending on the operating conditions of the engine, which varies during different phases of operation, such as idle, takeoff, or cruising speeds.

At lower speeds, one spray pattern may provide a finer atomization of fuel, which facilitates better mixing with air and promotes more efficient combustion. Conversely, at higher speeds, another spray pattern can deliver a coarser spray that ensures adequate fuel flow to maintain power and efficiency. This adaptability enhances the combustor's performance under varying operating conditions, resulting in more stable and complete combustion across the engine's operational range.

Understanding this concept is crucial as it directly impacts engine performance, fuel consumption, and overall efficiency in various flight scenarios.