Splitter plate (aeronautics)

A splitter plate, in the context of aeronautics and specifically aircraft engine inlets, is a structural component used to manage the airflow entering the engine. It is typically a flat or slightly curved plate positioned upstream of the engine's inlet, often extending outwards from the fuselage or wing. Its primary function is to divert the boundary layer airflow away from the engine inlet.

The boundary layer is a thin layer of slow-moving air that develops along the surface of an aircraft due to friction. This boundary layer air is turbulent and has a lower total pressure compared to the freestream airflow. Ingesting this low-energy air into the engine can reduce engine efficiency, cause engine instability (e.g., compressor stall), and increase drag.

The splitter plate effectively "splits" the airflow, channeling the boundary layer air (and any ingested debris) away from the engine inlet. By removing the boundary layer, the engine receives a cleaner, more uniform airflow, leading to improved engine performance and stability. The diverted boundary layer air is then typically discharged into the surrounding airflow. The design and position of the splitter plate are critical and are optimized through computational fluid dynamics (CFD) and wind tunnel testing to ensure effective boundary layer management and minimal drag penalty.