Swept Pylon Flap Vortex Mitigation for Tanker Refueling
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Solution Overview
Problem
Newer tanker aircraft operating at higher speeds experience stronger vortices during refueling due to increased side loads, causing instability in the hose and drogue systems, which existing aerodynamic mitigation designs fail to address effectively across the entire flight envelope.
Innovation Solution
The implementation of a swept pylon flap on the pylon attaching the pod to the wing assembly, with a shallow incidence angle at the uppermost portion increasing to a higher angle towards the lowermost portion, and the use of chines on the pod to create a counter-rotating vortex pair, disrupts the pod vortex and induces a downward flow that counters the vortex, stabilizing the hose and drogue during extension and retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the tanker aircraft operates at higher maximum speeds, then the aircraft performance and fuel delivery capability are improved, but stronger vortices are generated during refueling, causing hose and drogue instability
Solution Approach 1:
The patent converts the harmful strong vortices generated by high-speed operation into a beneficial effect by using swept pylon flaps to generate counter-rotating vortices. These counter-vortices actively cancel out the destabilizing upward vortices, transforming the high-speed operational advantage into a condition that maintains hose stability despite increased vortex strength
Solution Approach 2:
The patent changes the aerodynamic parameters of the pylon by adding swept flaps with specific incidence angles (5-15 degrees). This modification alters the flow field characteristics around the pod, creating controlled downward flow and counter-vortices that stabilize the hose system across the entire flight envelope, including high-speed refueling operations
2Stability of the object's composition
If existing aerodynamic mitigation designs (chines and Gurney flaps) are used, then low strength vortices across narrow regions are countered, but they are not effective for significantly higher vortex strengths across the entire flight envelope
Solution Approach 1:
The patent implements dynamic adaptability by designing swept pylon flaps that actively respond to varying flight conditions. The flaps generate counter-vortices and downward flow that scale with aircraft speed and vortex strength, providing continuous stabilization across the entire flight envelope from low-speed to high-speed refueling operations, unlike static existing designs
Solution Approach 2:
The patent adds a new dimensional approach by introducing swept flaps that extend in the spanwise direction from the pylon. This creates a three-dimensional flow control system that generates counter-rotating vortices and downward flow, adding vertical and spanwise flow control dimensions to address vortices that existing two-dimensional chines and Gurney flaps cannot effectively mitigate
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 configuration reduces side loads on the pod and pylon, stabilizes the hose and drogue by creating a downward flow that keeps them below the predominant vorticity region, addressing trail and retraction instabilities and maintaining alignment at refueling speeds.
Implementation Method 1
During flight, airflow creates vortices trailing the pod. Vortex flow is circular in a vertical plane and has an upward velocity component which can lift the hose and drogue
Implementation Method 2
The swept pylon flap is configured to create downward flow that counters a vortex trailing the pod
Implementation Method 3
The swept pylon flap comprises a leading edge and is configured to unload the pylon and pod during flight of the aircraft
Implementation Method 4
The control structure includes a high pressure engine nozzle that exhausts a high pressure fluid stream, which can be swirled using a deployable swirl vane architecture
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
An aircraft (110) comprises a wing assembly (130), a pod (176), and a pylon (178) attaching the pod (176) to the wing assembly (130). The pylon (178) has a swept pylon flap (410), which is configured to unload the pylon and pod during flight of the aircraft, and also to create downward flow that counters a vortex trailing the pod.