Longitudinal Vortex Flow Control for Drag Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preventing fluid flow separation on surfaces, such as aircraft aerfoils, are inadequate in maintaining energy input into the boundary layer over a large region, leading to inefficient lift and increased drag.
Innovation Solution
The method involves generating and enhancing longitudinal vortices using first and second flow actuators arranged along the surface, with the second actuators positioned downstream to increase vorticity and stabilize the vortices, thereby preventing flow separation by introducing energy into the boundary layer over a considerable distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compressed air is blown out in a pulsed manner onto the flow surface, then the boundary layer is energized and flow separation is prevented, but the energy input is insufficient over a large region along the flow direction
Solution Approach 1:
The flow surface is divided into multiple sections with first flow actuators at upstream locations and second flow actuators at downstream locations. This segmentation allows energy to be input at multiple discrete points along the flow direction, extending the region over which the boundary layer remains energized and preventing flow separation over a larger area.
Solution Approach 2:
By placing second flow actuators downstream of the first flow actuators, the patent creates a continuous chain of energy input along the flow direction. The longitudinal vortices generated by the first actuators are enhanced by the second actuators, ensuring that the useful action of energizing the boundary layer continues over an extended region rather than being limited to isolated pulsed locations.
2Use of energy by moving object
If longitudinal vortices are generated by first flow actuators, then energy is introduced into the boundary layer, but the vortices decay over distance and fail to prevent separation over a large region
Solution Approach 1:
The second flow actuators are positioned downstream to perform preliminary enhancement of the longitudinal vortices before they decay completely. By anticipating the natural decay of vortices and applying additional energy input at the optimal location, the system maintains vortex stability and effectiveness over a longer distance along the flow direction.
Solution Approach 2:
The second flow actuators change the parameters of the longitudinal vortices by enhancing their vorticity and reducing their cross-sectional area. This parameter modification reinforces the vortices against decay, allowing them to maintain their energy-input function over a larger region along the flow direction and effectively prevent flow separation.
3Stability of the object's composition
If second flow actuators are added downstream to enhance vortices, then vortex stability is improved, but the device complexity increases
Solution Approach 1:
Both the first and second flow actuators perform the same basic function of generating or enhancing longitudinal vortices to energize the boundary layer. This multi-functionality allows the system to extend vortex stability over a larger region without requiring fundamentally different or more complex actuator mechanisms, simply replicating the proven actuator design at different locations.
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 effectively stabilizes longitudinal vortices along the flow direction, preventing separation and reducing drag, while maintaining energy input into the boundary layer, thus enhancing lift and reducing pressure loss.
Implementation Method 1
Longitudinal vortices for suppressing or delaying the separation of the flow from the flow surface are generated by one or more first flow actuators associated with the flow surface
Implementation Method 2
Longitudinal vortices are thus able to introduce energy into the boundary layer of the fluid flow over a relatively large region of the flow surface along the flow direction
Data Source
AI summary
A method of preventing separation of a fluid flow flowing over a flow surface is described. The method includes generating longitudinal vortices for suppressing or delaying separation of the flow, and enhancing the longitudinal vortices. A flow body system having a flow body and a flow control arrangement is further described.