Sequential Nozzle Array for Aircraft Flow Control
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Solution Overview
Problem
Aircraft active flow control systems that employ continuous airflow to reduce separation and turbulence behind control surfaces require significant amounts of bleed air, leading to increased engine size, weight, and decreased flight efficiency.
Innovation Solution
An array of converging-diverging nozzles disposed on the control surface, activated sequentially to eject pressurized air in a streamwise direction, creating a wave pattern that maintains airflow attachment and reduces the need for constant airflow, thereby using significantly less supply air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If continuous airflow is used to reduce separation and turbulence behind control surfaces, then aerodynamic efficiency is improved, but engine size and weight increase due to significant bleed air requirements
Solution Approach 1:
The patent applies periodic action by using oscillating or pulsed jets from arrays of fluidic actuators instead of continuous airflow. The actuators are activated in sequences or waves, creating time-varying flow patterns that maintain aerodynamic effectiveness while significantly reducing the total amount of bleed air required from the engine
Solution Approach 2:
The patent segments the continuous airflow into discrete pulsed jets from multiple individual fluidic actuators arranged in arrays. These segmented actuators can be activated independently in sequences, allowing the system to achieve the desired flow control effect with less total airflow than continuous systems
2Reliability
If continuous airflow is used to maintain airflow attachment over control surfaces, then lift production is maintained, but fuel costs increase due to reduced flight efficiency
Solution Approach 1:
The oscillating and pulsed jet patterns from the fluidic actuators create periodic flow structures that effectively maintain airflow attachment and lift production. The time-varying nature of these jets allows the system to achieve reliable aerodynamic performance with significantly reduced energy consumption compared to continuous airflow systems
3Object-affected harmful factors
If significant amounts of bleed air are used in active flow control systems, then separation and turbulence are reduced, but device complexity increases
Solution Approach 1:
The fluidic actuators are designed to operate without external control systems, electronics, or power sources. They utilize the aircraft's existing aerodynamic environment and onboard air supply to generate the required jet patterns automatically, eliminating the complexity associated with traditional electronically-controlled flow control systems
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 improved aerodynamic efficiency and reduced weight by using approximately one-eighth the airflow of traditional systems, allowing for smaller engines and reduced fuel costs while maintaining lift production.
Implementation Method 1
A valve communicates with each of the nozzles and each of the nozzles is a converging-diverging nozzle. Pressurized air is supplied to the nozzles and the nozzles are activated in sequence to eject the pressurized air in the streamwise direction
Implementation Method 2
each of the nozzles is a converging-diverging nozzle. Pressurized air is supplied to the nozzles and the nozzles are activated in sequence to eject the pressurized air in the streamwise direction
Data Source
Figure 1
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AI summary
Example active flow control systems and methods for aircraft are described herein. An example method includes supplying pressurized air to a plurality of nozzles. The nozzles arranged in an array across a control surface of an aircraft, and the nozzles are oriented to eject the pressurized air in a substantially streamwise direction. The method further includes activating the nozzles to eject the pressurized air in sequence to create a wave of air moving in a spanwise direction across the control surface.