Aircraft Propulsion Nozzle with Deployable Obstructer for Sonic Boom Reduction
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Solution Overview
Problem
Aircraft propulsion systems face challenges in maintaining a continuously smooth jet plume contour across various flight conditions and engine power settings, leading to increased sonic boom magnitude due to over-expanded or under-expanded exhaust plumes at off-design conditions.
Innovation Solution
A propulsion system with a deployable obstructer and a variable area nozzle that adjusts based on pressure disparities between the exhaust plume and the ambient freestream, using sensors to control the obstructer and nozzle geometry to maintain a balanced pressure and reduce sonic boom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a fixed geometry nozzle is used, then the manufacturing precision is improved, but the adaptability to different flight conditions deteriorates
Solution Approach 1:
The nozzle incorporates movable flaps that can adjust the exit area dynamically based on flight conditions. This allows the fixed geometry nozzle body to maintain manufacturing precision while the movable flaps provide adaptability to different flight conditions by changing the effective exit area.
Solution Approach 2:
The nozzle exit is segmented into movable flaps that can be independently controlled. This segmentation allows selective adjustment of different portions of the exit area, providing fine-tuned adaptability to various flight conditions while maintaining the overall structural integrity and manufacturing precision of the nozzle body.
2Ease of operation
If the exhaust plume is allowed to expand or contract freely, then the ease of operation is improved, but the sonic boom magnitude increases
Solution Approach 1:
The movable flaps are positioned and controlled in advance to prevent the formation of strong shock waves. By adjusting the exit area before the exhaust plume encounters adverse pressure gradients, the system prevents the development of conditions that would lead to high sonic boom magnitudes.
Solution Approach 2:
The system uses pressure sensors to detect the actual pressure conditions of the exhaust plume and provides feedback to the control system. This feedback enables real-time adjustment of the movable flaps to maintain optimal plume expansion, preventing shock wave formation and reducing sonic boom while allowing natural plume behavior.
3Adaptability or versatility
If pressure sensors and control systems are added, then the adaptability to off-design conditions is improved, but the device complexity increases
Solution Approach 1:
The control system is designed to automatically adjust the movable flaps based on pressure sensor feedback without requiring complex external control mechanisms. The system serves itself by using the pressure information directly to drive the flap actuators, reducing the need for additional complex control electronics and software.
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 system achieves a quieter sonic boom signature across a broader range of operating conditions by precisely controlling the jet plume shape and pressure, reducing shock formation and sonic boom intensity.
Implementation Method 1
a first pressure sensor that is associated with the pathway and that is disposed to sense a static pressure of the mass flow at the trailing edge. The propulsion system further includes a second pressure sensor that is associated with the aircraft and that is disposed to sense an ambient pressure of a freestream proximate the aircraft
Implementation Method 2
The controller is configured to control at least one of the first deployable obstructer and the at least one of the throat and the trailing edge that is configured to enlarge and contract in a manner that reduces the disparity
Data Source
AI summary
A propulsion system for an aircraft includes: (1) an engine configured to generate a mass flow, (2) a nozzle having a pathway having a throat and a trailing edge, the throat or the trailing edge being configured to enlarge and contract, (3) a deployable obstructer disposed in the nozzle, (4) a first pressure sensor to sense the static pressure of the mass flow at the nozzle exit, (5) a second pressure sensor to sense the ambient pressure proximate the aircraft, and a (6) controller. The controller is coupled with the first and second pressure sensors, the deployable obstructer, and the throat or the trailing edge (whichever is configured to enlarge and contract). The controller receives the static and ambient pressures and when there is a disparity, the controller controls at least one of the deployable obstructer, the throat, and the trailing edge in a manner that reduces the disparity.