Third-Stream Gas Turbine Engine for Propulsive Efficiency

The engine flow is segmented into three separate streams: a core stream through the combustor, a first bypass stream around the core, and a second bypass stream (third stream) further outward. This segmentation allows each stream to be optimized independently, enabling the outer bypass stream to contribute to propulsive efficiency without requiring a single oversized fan, thus managing weight and packaging constraints.

The patent introduces a radial dimension to the bypass flow by creating an outer bypass stream that flows through an annular passage between the first bypass duct and the outer casing. This third stream utilizes the radial space more effectively, allowing the engine to achieve high propulsive efficiency without increasing the overall engine diameter excessively, thereby addressing packaging constraints.

The segmented three-stream configuration allows the engine to achieve high propulsive efficiency with a more compact overall structure. The separate bypass ducts and annular passages are modular in nature, facilitating easier integration into aircraft installations and reducing installation complexity compared to a single large-bypass-ratio engine.

By utilizing the radial annular space for the third stream, the engine achieves high efficiency without excessive diameter growth. This dimensional optimization results in a more compact engine package that is easier to install and integrate into aircraft structures.

The flow path is segmented into three distinct streams with separate control mechanisms. The inner bypass duct and outer annular bypass duct are independently configurable, allowing each stream to be optimized for different operating conditions. This segmentation enables superior propulsive efficiency across a wider range of flight regimes compared to conventional two-stream designs.

The patent incorporates variable geometry components including adjustable guide vanes and configurable bypass ducts that can adapt to different flight conditions. The third stream's annular passage geometry can be modified to optimize performance across varying speeds and altitudes, providing dynamic optimization that static two-stream designs cannot achieve.