Wind Tunnel Analytical Model

For the class midterm in ME347: Fluid Mechanics II, we were tasked to develop an analytical model of the wind tunnel in the Cal Poly Fluids Lab. The goal was simple: predict the wind speed in the test section given the fan speed selected on the Variable Frequency Drive (VFD) and compare that to experimental data. Below, you’ll find a description of the work I completed with partner Mallory Tevini.

Analysis

We started by developing a system curve for the entire wind tunnel system. This included factors accounting for losses due to the flow straightening veins, contractions, and expansions in the wind tunnel. With this equation, we turned our focus to the fan. With the manufacturer’s data, we generated the fan performance curve at each operating frequency, using fan scaling laws. These were then plotted in MATLAB along with the system curve to find the system operating points, at each frequency. From these operating points, and knowing the geometry of the test section, we calculated the predicted wind speed in the test section. This was then plotted against experimental data collected in the lab. In this plot, shown below next to the fan-system curve plot, we found that our model had an extremely strong correlation with the experimental data collected, within 5% in fact.