Fluidic Injectors for Jet Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional nozzle designs for high-pressure fluid exhaust in jet engines suffer from durability issues due to high temperature and generate significant noise, with existing solutions like ejector nozzles being heavy, bulky, and reducing engine performance.
Innovation Solution
A system of angled air jet injectors on both internal and external nozzle surfaces induces and sustains large-scale vortices, mixing actuation air with the exhaust plume to reduce noise and temperature, using fluidic injectors instead of mechanical actuation, and allowing for adjustable mixing rates based on flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional ejector nozzles are used to mix ambient air with exhaust plume, then exhaust plume temperature and jet noise are reduced, but the device becomes heavy, bulky and complex
Solution Approach 1:
The patent replaces complex mechanical mixing structures (lobed mixers, internal ejectors) with fluidic injectors that use fluid dynamics principles. The injectors create vortices through fluid injection alone, eliminating the need for heavy mechanical mixing components while achieving the same plume mixing effect.
Solution Approach 2:
The invention extracts the essential mixing function from the complex ejector nozzle structure and isolates it into separate fluidic injectors mounted on the nozzle surface. This separates the mixing function from the exhaust flow path, simplifying the overall nozzle design while maintaining effectiveness.
2Stability of the object's composition
If internal ejector mixer with lobed structure is used, then plume mixing is enhanced, but thrust loss and drag penalty increase due to larger diameter requirements
Solution Approach 1:
The patent divides the mixing function into multiple separate fluidic injectors distributed around the nozzle perimeter, each creating localized vortices. This segmented approach achieves comprehensive plume mixing without requiring a single large-diameter structure, thereby preserving thrust efficiency.
Solution Approach 2:
Instead of achieving mixing through increased diameter in the radial dimension, the invention uses fluidic injectors that create three-dimensional vortical structures. The vortices extend downstream in the axial dimension, providing effective mixing without increasing the nozzle's radial footprint.
3Stability of the object's composition
If delta-shaped tabs protruding into core exhaust stream are used, then vortex pairs are generated for mixing, but thrust loss occurs due to impeded exit flow
Solution Approach 1:
The patent introduces fluidic injectors as intermediary devices that generate vortices by injecting fluid into the exhaust stream, rather than using solid tabs that physically obstruct the flow. The injectors mediate between the need for vortex generation and the requirement for unimpeded exhaust flow, achieving mixing without thrust loss.
4Object-affected harmful factors
If saw-toothed trailing edges are used, then noise reduction is achieved, but weight penalty and constant drag are incurred
Solution Approach 1:
The patent replaces heavy mechanical saw-toothed trailing edge structures with fluidic injectors that create vortical flow patterns. These fluidic structures generate the same noise-reducing mixing effect without the weight penalty of solid mechanical features, as the mixing is achieved through fluid dynamics rather than physical geometry.
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 design effectively lowers jet noise and exhaust temperature, increases propulsive efficiency, and reduces weight and complexity, while maintaining performance across various flight conditions and applications.
Implementation Method 1
large scale vortices are induced and sustained
Implementation Method 2
one or more rows of angled air jet injectors
Implementation Method 3
These vortices mix actuation air with the exhaust plume
Implementation Method 4
The plume mixes out quickly, thereby lowering jet noise and jet exhaust temperature
Implementation Method 5
The high velocity produces a significant amount of jet noise. Small-scale eddies produce high frequency noise downstream from nozzle
Data Source
AI summary
A fluidic effector provides enhanced plume mixing for an aircraft engine. Air jet injectors are located on both the external and internal cowl surfaces and angled in opposite directions to induce large scale vortices in the exhaust plume. The vortices mix actuation air with the exhaust plume to produce ejector action. The plume mixes out quickly, thereby lowering jet noise and jet exhaust temperature. The injectors have orientations and injection rates that are adjustable to allow variable mixing rates for use at different flight and engine conditions.