Characterization and verification of a closed loop wind tunnel with a linear cascade and upstream wake generator
Master of Science in Mechanical Engineering (MSME)
A closed loop wind tunnel designed to study film cooling was completed in May 2011 along with a removable wake generating device. The test section featured a three blade, four passage linear cascade utilizing the Air Force Office of Scientific Research L1A low pressure turbine blade. The wake generator is unique because its blades are flat plates with round leading and trailing edges instead of circular rods. In this report, the test section of the wind tunnel is characterized and validated through velocity and pressure measurements in the test section. Hot-wire surveys were used to characterize the velocity and turbulence intensity. An in-house designed pressure blade along with Scanivalve pressure sensing equipment was used to acquire the static pressure on the surface of the center blade in the cascade. Incoming velocity results showed the profiles were uniform in both the horizontal and vertical directions. The turbulence intensity in the incoming freestream air was 0.20%. Installing the wake generator had no effect on the incoming velocity profiles. Experimental coefficient of pressure results with the wake generator installed were very close to the AFOSR results and fluctuated slightly when the wake generator was running. However, the overall shift in the coefficient of pressure magnitude as the wakes passed was small. Downstream velocity measurements in the wake of the cascade confirmed periodicity in the cascade. When the wake generator was running, the passing wakes effectively decreased the velocity and increased the turbulence intensity in the cascade wake, and caused the cascade wake to shift towards the suction side. It also increased the width of the cascade wake. Based on these results, the wind tunnel appears to be operating as designed and should produce adequate results in future film cooling measurements.
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Foreman, Christopher, "Characterization and verification of a closed loop wind tunnel with a linear cascade and upstream wake generator" (2013). LSU Master's Theses. 2469.