Variable Cycle Gas Turbine Auxiliary Propulsor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas turbine engines are inefficient at both supersonic and subsonic speeds, as they are optimized for either high exhaust velocities or large airflow volumes, making it difficult to achieve efficient performance across a wide range of operating conditions.
Innovation Solution
A variable cycle gas turbine engine design that includes a core engine, auxiliary combustor, auxiliary propulsor, bleed duct, and variable ductwork, allowing for two operational modes: high-speed mode with low bypass ratio and high fan pressure ratio, and low-speed mode with high bypass ratio and low fan pressure ratio, by directing airflow through the engine differently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is designed with high exhaust velocity to optimize supersonic performance, then propulsive efficiency at high speeds is improved, but propulsive efficiency at low speeds deteriorates
Solution Approach 1:
The patent implements variable cycle operation where the engine can dynamically switch between different operational modes (high-speed mode with low bypass ratio and high fan pressure ratio, and low-speed mode with high bypass ratio and low fan pressure ratio). This dynamic adaptability allows the engine to optimize its airflow and pressure ratios based on operating conditions, resolving the contradiction between high-speed and low-speed efficiency.
2Quantity of substance
If the engine is designed with large airflow volume to optimize subsonic performance, then propulsive efficiency at low speeds is improved, but propulsive efficiency at high speeds deteriorates
Solution Approach 1:
The engine incorporates variable ductwork and controllable bypass passages that allow dynamic adjustment of airflow distribution. In high-speed mode, the system reduces bypass ratio to minimize airflow volume while maintaining high exhaust velocity. In low-speed mode, it increases bypass ratio to maximize airflow volume, thereby optimizing propulsive efficiency across different speed regimes.
3Productivity
If the bypass ratio is increased to improve low-speed efficiency, then thrust production at subsonic speeds is improved, but exhaust velocity and high-speed efficiency deteriorate
Solution Approach 1:
The patent employs controllable bypass passages and variable ductwork that enable the engine to dynamically adjust the bypass ratio based on operating conditions. At subsonic speeds, the system opens bypass passages to increase airflow and thrust production. At supersonic speeds, it closes bypass passages to maximize exhaust velocity, thus resolving the contradiction between thrust production and exhaust velocity.
4Stress or pressure
If the fan pressure ratio is increased to improve high-speed efficiency, then exhaust velocity is improved, but fan airflow and low-speed efficiency deteriorate
Solution Approach 1:
The engine incorporates variable cycle operation with controllable bypass passages that allow dynamic adjustment of fan pressure ratio and airflow. In high-speed mode, the system increases fan pressure ratio to optimize exhaust velocity while managing airflow through the core engine. In low-speed mode, it reduces fan pressure ratio and increases bypass airflow, thereby resolving the contradiction between pressure ratio and airflow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The engine achieves improved propulsive efficiency across a broad range of speeds by optimizing airflow and pressure ratios in different operating modes, enhancing performance at both high and low speeds.
Implementation Method 1
The auxiliary propulsor includes a fan to accelerate air to produce thrust
Implementation Method 2
The exhaust gas exits the nozzle at a higher velocity than the velocity of the inlet air thereby producing thrust with the net acceleration of the flow
Implementation Method 3
a core combustor to add fuel and ignite the pressurized air into a propulsive gas flow
Implementation Method 4
a core turbine that is rotated by the propulsive gas flow, which in turn rotates the core compressor through a core shaft
Implementation Method 5
a core compressor to pressurize air entering into an inlet portion of the engine
Data Source
AI summary
A core engine of a variable cycle gas turbine engine includes a low pressure spool for generating streams of bypass air and pressurized air, and a high pressure spool for further pressurizing the stream of pressurized air to generate streams of combustion air and supercharged auxiliary air. A peripheral case surrounds the engine case to form a peripheral duct. An auxiliary combustor and propulsor are positioned within the peripheral duct. A bleed duct extends from the high pressure spool to the auxiliary combustor. Variable ductwork directs airflow through the bleed duct and peripheral duct in two modes. A first mode comprises directing the stream of auxiliary air to the auxiliary combustor, and directing stream of inlet air through the peripheral duct. A second mode comprises directing the stream of auxiliary air into the stream of bypass air, and preventing inlet air from entering the peripheral duct.