Available at: http://digitalcommons.calpoly.edu/theses/1105
Date of Award
MS in Mechanical Engineering
To continue the development of the Boundary Layer Data System (BLDS), a constant voltage hot-wire anemometer (CVA) is implemented into the BLDS for flight-testing. The hot-wire anemometer was chosen as an alternative to the traditional pressure probe because of the ability to measure both average velocity and fluctuating velocity within the boundary layer. Previous work done on the benchtop has led to the design of miniaturization, flight-capable hardware for the BLDS. The next step in the development of the BLDS – CVA calls for quantifying the accuracy of the boundary layer measurements measured by the CVA system. To do this, numerous turbulent boundary layer velocity and fluctuating velocity profiles were taken on a flat-plate at various speeds within the Cal Poly 2x2 wind tunnel with both the traditional pressure probe and the CVA. These test resulted showed agreement between the hot-wire and pressure probe data. Once this was completed the new CVA hardware was tested along with the new software that was written for the BLDS – CVA. In addition, due to the limited memory space onboard the BLDS – CVA, an approximation had to be developed to convert the average voltage data from the BLDS – CVA to the average velocity data due to the non-linear calibration function. The approximation developed was able to match the exact values from a traditional calibration. Lastly, due to the inability to perform a laboratory calibration of the hot-wire at altitude, where the conditions differ significantly from the ground conditions, a new procedure for hot-wire calibration was developed. The method developed was validated through wind tunnel testing and a computer thermal/electric model. With the completion of this work, the BLDS – CVA is ready for flight-testing.