SUPERVISOR
Dr. Camli Badrya
ROLE
Student Researcher
Project Lead
DATE
Oct. 2024 β Feb. 2025
This project involved restoring and improving a Rolling Hills Research Corporation model 0710 water flume. I designed and implemented an innovative dye injection system that allows for precise flow rate control, enabling detailed demonstrations for blunt body shapes and airfoils. The system features adjustable sideslip and attack angles, a manual airflow manifold, 2 sets of dye line regulators, and 6 distinct dye lines.
After sourcing components and ensuring their compatibility, I constructed the system and produced demonstrative videos throughout the academic year.
To complement my practical work, I delved into academic literature on flow visualization research using water tunnels, which provided an excellent foundation in the world of fluid mechanics beyond undergraduate classes. Along with this, I authored an abstract on blunt-body and airfoil flow visualisation using the water and smoke tunnels presenting my work at The Northern California Aerospace Symposium as well as UCDavis' annual undergraduate research competition.
Purpose & Scope
The water flume, initially non-operable, had multiple leaks and an outdated dye delivery system. Most components were at the end of their life cycle and our lab was not able to source the correct parts to repair the system. Instead of purchasing a newer model, I undertook itβs repair and modernization.
The goal was a new incompressible and pneumatic system which could reliably visualize and replicate intricate flow phenomena with the use of 6 distinct dye colors.
This entailed background research into what aerodynamic and even hydrodynamic phenomena can be visualized through use of a water flume. To build on this, some research was done on how to keep flow as laminar as possible, how to capture and quantify results, how to ensure a system which could be improved upon in the future to accommodate more intricate use cases.
With this in mind, I sketched an initial design and compiled a parts list with a cost breakdown.
This was presented to my principal investigator and supervising graduate student and the project was approved.
Water pump line and drain valve install
Water pump line and drain valve replacement
New components
Air line shutoff valves
Dye line shutoff valves
Flow regulators
Fabrication
Before building installing the new dye injection system, the water circulation system had to be repaired. There was a large leak underneath the water drainage valve and cracks in the original piping, so roughly half the circulation system was cut out and rebuilt using PVC piping.
After testing for leaks and ensuring the system was safe to fill, I started inserting lines into the dye containers, through their caps, which were pressurized with air. This directed dye up the lines and into flow regulators, with 2 sets of integrated shutoff valves β one for the air pumped into the containers and one for the dye exiting them.
After the dye passed through the regulators, which allowed for individual adjustment of the dye output and color presence during operation, they ran through another set of lines which directed them into the model sitting inside the water flume.
A grid mat was added to the rear viewing window of the water flume, allowing for numerical analysis of wake length and size, along with location of boundary layer separation and further phenomena.
Difficulties
Rolling Hills Research Corporation, which produced our model 0710 water flume, was permanently closed. The inability to obtain replacement parts sparked creativity to figure out what parts could be used as replacements or as part of the new system.
Some examples of engineering creativity:
- Large syringes were purchased to test the operating pressures of each dye line and dye flow rate control knob.
- Aquarium tank vales were retrofitted as manual shut-off ball-valves.
- Metal pipes were used to create detachable connections between dye lines for easy model replacement during demonstrations.
When initially repairing the water circulation system, the first attempt created vibrations which created ripples along the surface of the water. These disturbances also affected the dye streamlines, causing early breakdown of phenomena and difficultly quantifying results using the grid. After troubleshooting, I discovered that the pipe segment I had fabricated as a replacement had a smaller diameter than the original piping. This cross sectional area change created turbulence in the water circulation system before water entered the pump, to be sent up and into the front end of the water flume. A new pipe segment was fabricated to match original pipe diameter and attachments were used to allow disassembly of this segment for partial repairs. Another creative idea was to use a plumbing pipe attachment which was extendable and variable in length.
The new segment was slotted into the empty space and the extendable pipe segment was lengthened to slide over the original piping and complete the water circuit.
Securing the dye and air lines to the system also presented itself to be a challenge. The dye containers, which had to be regularly filled, required removal from the system and their caps harbored the hardware which enabled dye extraction. In the video shown above, tape was used to temporarily secure the dye lines during testing β this was later replaced by carefully placed 3D printed clips which could be moved or removed for full accessibility to the system.
Results
The videos above show a delta wing at zero, low, and high angles of attack. The visualized phenomena included vortices, wakes caused by pressure drag, flow separation, laminar and turbulent boundary layers, and even vortex shedding. All predicted aerodynamic phenomena were successfully replicated and demonstrated amongst the delta wing, various airfoils and blunt body objects. These results were successfully replicated during remonstrations and during video production.
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Undergraduate Research Conference Poster