Scale Effects

In most boundary layer wind tunnels, researchers test models of large civil engineering structures with geometric scales ranging from 1:500 to 1:100. However, producing aerodynamic models of solar panels at such scales makes the modules too small, resulting in at least two technical problems. First, the resolution of pressure data on such small models becomes low. Second, the test model could be in the lower portion of the boundary layer, which is not a true representative of a real-world scenario due to high uncertainty in wind velocity. To alleviate these problems, the development of a standardized testing protocol is essential. Such protocol should account for the time and geometric scales to accurately assess wind loads on the structures. This research systematically investigates the sensitivity of wind loads to testing ground-mounted solar panels, both experimentally (in a wind tunnel) and numerically (by computational fluid dynamics (CFD), at different geometric scales. While mean loads are not significantly affected by the model size, peak loads are sensitive to both the geometric scale and the spectral content of the test flow. However, when the objective is to predict 3-s (three seconds) peak loads, larger scales are feasible.

Our findings suggest a location of the test building, different from existing guidelines, and the inflow boundary proximity influence the pressure correlation and the reproduction of peak loads. The CFD LES results are comparable to corresponding pressures from the open jet, full scale, wind tunnel, and the ASCE 7-10 standard for roof Component & Cladding design. The CFD LES shows its adequacy to produce peak pressures/loads on buildings, in agreement with field pressures, due to its capabilities of reproducing the spectral contents of the inflow at a 1:1 scale.

 

Scale Effects

 

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Selected Publications