Variable Inlet Guide Vanes for Aircraft Reverse Thrust Control
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Solution Overview
Problem
Current aircraft systems lack effective means to increase reverse thrust during descent, particularly beyond the windmilling regime, limiting the ability to slow down the aircraft efficiently.
Innovation Solution
A variable geometry mechanism, such as Variable Inlet Guide Vanes, is used to modulate compression work by adjusting its opening angle, increasing the amount of compression work performed by the compressor, thereby enhancing reverse thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the blade angle is reduced to maintain constant speed during descent, then the propeller operates in windmilling regime providing reverse thrust, but the reverse thrust is insufficient to further slow down the aircraft
Solution Approach 1:
The patent changes the operating parameters of the compressor by adjusting the variable geometry mechanism opening angle. This modifies the compression work performed by the compressor, thereby increasing the reverse thrust generated by the propeller in windmilling regime without requiring additional hardware systems
Solution Approach 2:
The patent utilizes the existing compressor and variable geometry mechanism of the engine to generate additional reverse thrust. The compressor's compression work directly contributes to increasing reverse thrust, making the existing system serve dual purposes of normal compression and reverse thrust generation
2Force
If additional hardware like mechanical brakes is installed to increase reverse thrust capability, then aircraft deceleration improves, but system complexity increases
Solution Approach 1:
The patent makes the existing variable geometry mechanism and compressor perform an additional function - generating reverse thrust during descent. The same compressor that performs compression during normal operation now also contributes to reverse thrust generation, eliminating the need for separate brake systems
Solution Approach 2:
The patent merges the reverse thrust generation function with the existing compression system. By adjusting the variable geometry mechanism, the compressor's work is utilized to increase reverse thrust, combining two functions into one integrated system rather than adding separate mechanical brake components
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
This solution allows for increased reverse thrust capabilities beyond the windmilling regime, improving aircraft maneuverability and descent efficiency by providing additional aero braking, reducing system complexity, and eliminating the need for additional hardware like mechanical brakes.
Implementation Method 1
a variable geometry mechanism provided upstream of the compressor and configured to modulate an amount of compression work performed by the compressor
Implementation Method 2
The operating zone known as 'windmilling' is reached when the propeller is entirely driven by the speed of the aircraft. In that state, the propeller is providing reverse thrust
Data Source
AI summary
A method and a system for providing in-flight reverse thrust for an aircraft are provided. The aircraft comprises an engine having a rotor, a compressor mechanically coupled to the rotor, and a variable geometry mechanism provided upstream of the compressor and configured to modulate an amount of compression work performed by the compressor. The method comprises operating the rotor with the variable geometry mechanism in a first position, receiving a request to increase reverse thrust for the rotor, in response to the request, adjusting the variable geometry mechanism from the first position towards a second position, the variable geometry mechanism having a greater opening angle in the second position than in the first position, and operating the rotor with the variable geometry mechanism in the second position for causing an increase in the amount of compression work performed by the compressor and an increase in reverse thrust for the rotor.