Delta Wing Models for Wind Tunnel Applications
In this project, I designed and manufactured two fighter jet scaled wing planforms to study vortex lift at Cal Poly's Low Speed Wind Tunnel.
I first measured the geometry of the Lockheed F-35 and F-117 and created cut files for them, and then scaled the models to both have wingspans of 18 inches. Next, I cut out the models from recycled plywood using a CNC laser and cut a chamfer on the leading edge using a table saw. After painting the wood, sanding it very smooth to have a smaller boundary layer, and installing threaded inserts for the mount, I rastered the wing specifications on each planform, again using the laser.
The purpose of the wedge-shape on the leading edge is to demonstrate vortex lift, a phenomena that is created by the turning of flow from the bottom side of the wing to the top. When the wedge pushes the free-stream down, it creates a high pressure zone just beneath the leading edge and a low pressure zone above the leading edge, on the flat surface. The pressure differential turns the flow from high to low regions, creating a turning of the flow around the leading edge, generating a lift force on the wing. Part of what affects the generated lift force is the sweep angle, or the angle measured from the horizontal plane of the wing section back to the leading edge. This is why the F-117 and F-35 sections were selected, because they have drastically different sweep angles.
Finally, I tested the sections. Not only are they useful for load cell measurements to characterize the lift force generation, but they are also spectacular for flow visualization. I used cedar smoke at the inlet of the tunnel to make the flow more visible, and then implemented a mounting system for a laser underneath the test section of the tunnel to illuminate the cross section of the flow. Multiple stills of these cross sections are overlayed in the image attached, truly depicting the vortex along the leading edge and how it develops further down the wing. These two wing planforms are now used for aerospace engineering labs at Cal Poly.
This experience was very valuable, as I taught myself how to design a wind tunnel test from start to finish. In addition, it was a great way to deepen my understanding of gas dynamics and fluid mechanics. I would like to thank Dr. Hiremath for providing me with this great learning opportunity.
I first measured the geometry of the Lockheed F-35 and F-117 and created cut files for them, and then scaled the models to both have wingspans of 18 inches. Next, I cut out the models from recycled plywood using a CNC laser and cut a chamfer on the leading edge using a table saw. After painting the wood, sanding it very smooth to have a smaller boundary layer, and installing threaded inserts for the mount, I rastered the wing specifications on each planform, again using the laser.
The purpose of the wedge-shape on the leading edge is to demonstrate vortex lift, a phenomena that is created by the turning of flow from the bottom side of the wing to the top. When the wedge pushes the free-stream down, it creates a high pressure zone just beneath the leading edge and a low pressure zone above the leading edge, on the flat surface. The pressure differential turns the flow from high to low regions, creating a turning of the flow around the leading edge, generating a lift force on the wing. Part of what affects the generated lift force is the sweep angle, or the angle measured from the horizontal plane of the wing section back to the leading edge. This is why the F-117 and F-35 sections were selected, because they have drastically different sweep angles.
Finally, I tested the sections. Not only are they useful for load cell measurements to characterize the lift force generation, but they are also spectacular for flow visualization. I used cedar smoke at the inlet of the tunnel to make the flow more visible, and then implemented a mounting system for a laser underneath the test section of the tunnel to illuminate the cross section of the flow. Multiple stills of these cross sections are overlayed in the image attached, truly depicting the vortex along the leading edge and how it develops further down the wing. These two wing planforms are now used for aerospace engineering labs at Cal Poly.
This experience was very valuable, as I taught myself how to design a wind tunnel test from start to finish. In addition, it was a great way to deepen my understanding of gas dynamics and fluid mechanics. I would like to thank Dr. Hiremath for providing me with this great learning opportunity.
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