What can I do to make my wind tunnel testing project more complex?

• Vinnende
In summary, my supervisor thinks the project is not complex enough and I need to do more theoretical calculations.
Vinnende
Hello all,

I'm in my final year of engineering so I'm required to complete a thesis as part of that. My topic is to investigate the wind loading on a typical conveyor belt + truss arrangement, because there's a lot of uncertainty in industry about drag coefficients etc. I've attached a model of the steel structure below (simplified by removing members parallel to flow), but there's also lots of other services and the conveyor belt itself not pictured. It's 18m long.

http://i.minus.com/jsD6rCU01EZXt.png

Anyway, my plan is to construct a scale model ~(1:10) and do a variety of wind tunnel tests in my universities wind tunnel (sahweet!) for different arrangements/alignments/etc, with the major output being drag force (assuming the other forces and moments are negligible). The problem is, my supervisor doesn't think the whole project is theoretically complex enough, and I guess he's right - at the end of the day all I'm doing is measuring drag on a model.

So my question is, how can I make this project more complex? Right now the only real calculations involve some dimensional analysis/similitude (which I'll try to make as elegant and clever as possible). What else can I do/investigate? Essentially I want to show/prove that I've done my research and know the theory behind the results, so I'd love to include some sort of theoretical analysis, but obviously the complicated geometry makes anything I do by hand irrelevant. I was thinking perhaps include flow visualization in some wind tunnel tests and then discuss the boundary layers/flow separation/turbulence onset, but then what's the point? It's not like the dynamic behaviour of the wind will adversely affect its structural integrity.

Essentially I just want to prove I know my stuff, whilst keeping it relevant to the topic. I'd love to do some sort of CFD analysis, but I fear the geometry is far too complex and I also don't know much about CFD . But if performing a simulation over a small section could provide further insight (and not take forever) I'd love to have a crack!

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I think flow viz could be interesting because the dynamic behavior of the air is certainly important. Turbulence and vortex shedding result in unsteady loading on the body. This unsteady loading can excite certain structural modes and cause serious problems. It also generates noise. I would suggest mini tufts, surface oil flow and smoke wire methods for flow viz.

You could try various modifications to reduce the drag like fairings.

You can do pretty interesting things by measuring pressure and velocity components in the wake of a 3D body. For example with measurements from a five hole probe you can decompose the total drag into profile drag and vortex induced drag. But that would take a considerable amount of additional effort.

If you have the equipment you could perform a simple wake survey with an array of pitot probes and perform a control volume momentum analysis. Or you could make boundary layer measurements and calculate the skin friction.

Thanks very much for your reply! Certainly things I can look into :)

1. What is wind tunnel testing?

Wind tunnel testing is a method used to study the effects of air flow on various objects or models. It involves placing the object or model in a controlled wind tunnel and measuring the forces and pressures exerted on it by the air flow.

2. Why is wind tunnel testing important?

Wind tunnel testing is important because it allows scientists and engineers to understand the aerodynamic properties of objects or models. This information can then be used to improve the design and performance of various technologies, such as airplanes, cars, and buildings.

3. What are some common applications of wind tunnel testing?

Wind tunnel testing is commonly used in the aerospace industry for designing and testing aircraft and spacecraft. It is also used in the automotive industry for improving the aerodynamics of cars. Other applications include testing the effects of wind on buildings, bridges, and sports equipment.

4. How is wind tunnel testing conducted?

Wind tunnel testing involves placing the object or model in a wind tunnel and subjecting it to controlled air flow. The air flow is created by powerful fans or compressors and is directed over the object at various speeds and angles. Sensors and instruments are used to measure the forces and pressures exerted on the object by the air flow.

5. What are the benefits of wind tunnel testing?

Wind tunnel testing offers several benefits, including the ability to accurately measure and analyze the aerodynamic properties of objects, the ability to simulate various wind conditions, and the ability to make necessary design improvements before testing in real-world conditions. It also allows for cost-effective testing and can help reduce the risk of failure in real-world applications.

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