Variable Area Thrust Nozzle for Supersonic Turbofan
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Solution Overview
Problem
Supersonic aircraft require propulsion systems that balance high take-off thrust with low exhaust jet noise, while minimizing drag and fuel consumption, which is challenging due to competing demands on fan diameter and engine architecture complexity.
Innovation Solution
A turbofan engine with a supersonic intake, variable area thrust nozzle, and a controller that adjusts the nozzle throat area and fuel flow to optimize thrust and noise levels across different flight operations, allowing for high thrust during take-off and reduced noise during climb by varying the nozzle area and relative airflow ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the fan diameter is increased to provide high take-off thrust, then take-off thrust is improved, but drag at supersonic cruise increases and fuel consumption increases
Solution Approach 1:
The patent applies a variable area thrust nozzle that dynamically adjusts its throat area based on flight conditions. During take-off, the nozzle operates at a smaller area to generate high exhaust jet velocity and high thrust. During supersonic cruise, the nozzle expands to a larger area to reduce exhaust jet velocity and thereby reduce wave drag. This dynamic adaptation allows a single fan diameter to satisfy both high thrust and low drag requirements.
Solution Approach 2:
The patent changes the physical parameter of the nozzle throat area to optimize performance across different flight regimes. By varying the throat area, the exhaust jet velocity is adjusted: high velocity for take-off thrust, low velocity for cruise drag reduction. This parameter change enables the engine to achieve high take-off thrust with a smaller fan while maintaining low drag during cruise.
2Object-generated harmful factors
If the fan diameter is increased to reduce exhaust jet noise, then jet noise is reduced, but drag at supersonic cruise increases and fuel consumption increases
Solution Approach 1:
The variable area thrust nozzle dynamically adjusts the throat area to control exhaust jet velocity and noise levels. During take-off, the smaller throat area produces high velocity jets necessary for thrust. During climb and cruise phases, the nozzle expands to larger areas that reduce exhaust jet velocity and consequently reduce jet noise to comply with regulations, all while maintaining a smaller fan diameter.
Solution Approach 2:
By changing the throat area parameter, the system controls the relationship between exhaust jet velocity, noise generation, and thrust. The variable area allows the engine to achieve noise reduction without increasing fan diameter, thereby avoiding the penalty of increased drag and fuel consumption.
3Adaptability or versatility
If a variable geometry intake is provided to match intake throat area with flow required by the engine, then intake performance is improved, but device complexity increases
Solution Approach 1:
Instead of making the intake variable geometry to adapt to different flow requirements, the patent inverts the approach by making the thrust nozzle variable geometry. The fixed geometry intake simplifies the upper works, while the variable area nozzle in the lower works provides the necessary adaptability for different flight conditions, reducing overall system complexity.
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 solution achieves high take-off thrust with reduced fan diameter, minimizing drag and fuel consumption, while complying with noise regulations by adjusting the nozzle area and airflow ratios, thus enhancing aircraft range and noise compliance.
Implementation Method 1
a supersonic intake for slowing down incoming air to subsonic velocities at an inlet to the fan formed by the intake
Implementation Method 2
a mixer for mixing an exhaust gas flow exiting the engine core and the bypass airflow exiting the bypass duct
Data Source
AI summary
A turbofan engine has an engine core including in flow series a compressor, a combustor and a turbine. The engine further has a fan located upstream of the engine core, has a supersonic intake for slowing down incoming air to subsonic velocities at an inlet to the fan formed by the intake, has a bypass duct surrounding the engine core, wherein the fan generates a core airflow to the engine core and a bypass airflow through the bypass duct, and has a mixer for mixing an exhaust gas flow exiting the engine core and bypass airflow exiting bypass duct. The engine further has a thrust nozzle rearwards of the mixer for discharging mixed flows, the thrust nozzle having a variable area throat. The engine further has a controller controlling the thrust produced by the engine over a range of flight operations including on-the-ground subsonic take-off and subsequent off-the-ground subsonic climb.