Active Flow Control Nozzle Array for Aircraft
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Solution Overview
Problem
Existing active flow control systems for aircraft require significant amounts of bleed air, leading to increased engine size, weight, and decreased flight efficiency due to the need for continuous airflow across control surfaces to prevent airflow separation.
Innovation Solution
An array of nozzles oriented to eject pressurized air in a streamwise direction across control surfaces, activated in sequence to create a wave of air that moves spanwise, reducing airflow separation with significantly less air supply, using converging-diverging nozzles to accelerate air to supersonic speeds and employing wave patterns to maintain airflow attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous airflow is supplied across control surfaces to prevent airflow separation, then airflow attachment is maintained and lift is improved, but significant amounts of bleed air are required leading to increased engine size, weight, and decreased flight efficiency
Solution Approach 1:
The patent applies periodic action by activating nozzles in a sequential wave pattern rather than continuously. The controller activates nozzles in sequence from inboard to outboard and back, creating a moving wave of pressurized air that periodically energizes the boundary layer across the control surface, maintaining airflow attachment with intermittent rather than continuous air supply.
Solution Approach 2:
The patent segments the control surface into multiple zones with individual nozzles distributed across it. Each nozzle treats a specific segment of the control surface independently, allowing the system to address airflow separation locally in each segment rather than requiring continuous air supply across the entire surface.
2Reliability
If significant amounts of bleed air are used for flow control, then airflow separation is prevented, but engine size and weight increase
Solution Approach 1:
By using periodic wave-like activation of nozzles instead of continuous air supply, the system reduces the total volume of bleed air required, thereby reducing the size and weight of the engine and associated air supply infrastructure while maintaining effective flow control.
Solution Approach 2:
The patent applies partial action by supplying air to only a portion of the nozzles at any given time through the sequential wave pattern, rather than activating all nozzles simultaneously or continuously. This partial activation achieves sufficient flow control with reduced air consumption.
3Reliability
If continuous airflow is supplied across control surfaces, then lift is maintained, but fuel consumption and emissions increase
Solution Approach 1:
The sequential wave pattern creates periodic bursts of pressurized air that maintain lift production without requiring continuous air supply. This periodic action reduces the energy required for flow control, thereby decreasing fuel consumption and emissions while preserving lift.
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 approach reduces airflow separation, increases lift production, and decreases the resources needed for airflow control, resulting in lighter aircraft engines, reduced fuel consumption, and lower emissions by using approximately one-eighth the airflow of traditional systems.
Implementation Method 1
supplying pressurized air to a plurality of nozzles. The nozzles are 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
Implementation Method 2
using converging-diverging nozzles to accelerate air to supersonic speeds
Implementation Method 3
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
Implementation Method 4
the airflow over the top of the wing separates from the airflow along the bottom of the wing and reattaches downstream of the wing. However, the airflow over the top of the wing does not follow the entire upper surface of the wing and control surface
Implementation Method 5
This separation pocket produces drag and decreases the lift generated by the wing
Data Source
AI summary
Example active flow control systems and methods for aircraft are described herein. An example active flow control system includes a plurality of nozzles arranged in an array across a surface of an aircraft. The nozzles are oriented to eject air across the surface to reduce airflow separation. The active flow control system also includes an air source coupled to the nozzles and a controller to activate the nozzles to eject air from the air source in sequence from outboard to inboard and then from inboard to outboard to create a wave of air moving from outboard to inboard and then from inboard to outboard across the surface.