J. Scott Thompson
Honors in Physics: Experimental Aerodynamics: Design and Construction of a Wind Tunnel and Focusing Schlieren Optical System
A wind tunnel and Schlieren optical systems were designed to study experimental aerodynamics and both qualitative and quantitative flow visualization. The wind tunnel was designed to achieve laminar flow in the test section with wind speeds that approach the speed of sound. A 30 diameter fan powers the wind tunnel. A Schlieren system takes advantage of the relationship between air density and refractive index to visualize air flow and convection currents. Here, a focusing Schlieren system was designed, which uses source and cutoff grids, essentially creating multiple overlapping Schlieren systems, and particular planes in the test section can be focused sharply. By placing a Charge Coupled Device (CCD) camera at the image plane, the incident light intensity is recorded by a computer and changes in light intensity are related to changes in refractive index. This can then be used to calculate the pressure or temperature gradient of the fluid through the ideal gas law. However, quantitative measurements were not possible with the current systems due to equipment problems and low Schlieren system sensitivity.