Rotatable Supersonic Caret Inlet for Variable Capture Area
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fixed-geometry supersonic aircraft inlets are inefficient at varying Mach numbers, leading to suboptimal pressure recovery and increased drag due to fixed capture area, which results in excess airflow spillage and additional drag, limiting the performance of modern fighter aircraft.
Innovation Solution
A rotatable caret inlet with an off-body axis of rotation, allowing for variation in capture area and ramp angle, coupled with a diffuser in a scrubbing relationship to maintain a seal during rotation, optimizing pressure recovery and minimizing drag across a range of subsonic and supersonic velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed-geometry inlet is used, then the inlet structure is simple, but pressure recovery is suboptimal at varying Mach numbers and drag increases due to excess airflow spillage
Solution Approach 1:
The inlet system employs movable compression ramps that can adjust their angle relative to the fuselage centerline, transforming the fixed-geometry inlet into a dynamic system. This allows the inlet to optimize its capture area and ramp geometry for different Mach numbers, improving pressure recovery efficiency while managing the complexity through a controlled adjustment mechanism
Solution Approach 2:
The inlet system changes geometric parameters (ramp angle and capture area) in response to varying flight conditions. By adjusting the ramp angle and capture area based on Mach number, the system optimizes pressure recovery at different operating points, resolving the contradiction between fixed structure simplicity and variable performance requirements
2Device complexity
If a fixed capture area is used, then the inlet structure is simple, but drag increases due to excess airflow spillage at lower speeds
Solution Approach 1:
The movable compression ramps enable dynamic adjustment of the capture area, allowing the inlet to reduce its effective capture area at lower speeds to minimize spill drag, while maintaining a simple overall structure that only requires ramp adjustment mechanisms rather than complete inlet reconstruction
3Productivity
If the inlet rotates about an off-body axis, then capture area and ramp angle can be optimized, but sealing complexity increases
Solution Approach 1:
The diffuser inlet interface is designed with a curved surface that rotates about an off-body axis, creating a scrubbing action between the diffuser inlet surface and the caret inlet trailing edge. This curved geometry enables effective sealing through the rotational scrubbing motion itself, reducing the need for additional complex sealing mechanisms while maintaining optimization capability
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 enables efficient operation by maximizing pressure recovery and minimizing drag across the Mach envelope range, enhancing thrust and fuel efficiency while maintaining a sealed interface without additional mechanical complexities.
Implementation Method 1
The inlet is rotatable about an off-body axis for compression ramp angle and capture area variation
Implementation Method 2
a diffuser is engaged to the inlet in a scrubbing relationship to maintain a seal upon rotation of the inlet
Implementation Method 3
maximizing pressure recovery and minimizing drag across the Mach envelope range
Implementation Method 4
minimizing inlet spill drag to maximize the propulsion system net propulsive force
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 2C~2D
AI summary
An engine inlet (10) for efficient operation in both subsonic and supersonic flight wherein the inlet has a caret configuration, is rotatable about an off-body axis (30) for compression ramp angle and capture area variation and a diffuser (14) is engaged to the inlet in a scrubbing relationship to maintain a seal upon rotation of the inlet.