Browsing by Author "Reagle, Colin James"

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    Heat Transfer Measurements Using Thin Film Gauges and Infrared Thermography on a Film Cooled Transonic Vane
    Reagle, Colin James (Virginia Tech, 2009-05-04)
    This work presents a comparison of thin film gauge (TFG) and infrared (IR) thermography measurement techniques to simultaneously determine heat transfer coefficient and film cooling effectiveness. The first comparison was with an uncooled vane where heat transfer coefficient was measured at Mex=0.77 and Tu=16%. Relatively good agreement was found between the results of the two methods and the effect of recovery temperature and data reduction time was analyzed. Improvements were made to the experimental set up for the next comparison, a showerhead film cooled vane. This geometry was tested at BR=0, 2.0, Mex=0.76 and Tu=16%. The TFG and IR results did not compare well for heat transfer coefficient or film cooling effectiveness. The effects of measured and calculated recovery temperature were analyzed as well as the respective data reduction methods, though the analysis could not account for the effectiveness trend seen on the suction surface. Finally, a vane with showerhead and shaped film cooling holes were presented at BR=0, 1.7, 2.0, 2.8, Mex=0.85, and Tu=13% to assess a new film cooling geometry measured with the IR technique. Similarities on the suction surface trend between the different film cooled geometries tested with IR indicate a flaw in the experiment that will require further analysis, changes and testing to complete the comparison with TFG.
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    Technique for Measuring the Coefficient of Restitution for Microparticle Sand Impacts at High Temperature for Turbomachinery Applications
    Reagle, Colin James (Virginia Tech, 2012-08-22)
    Erosion and deposition in gas turbine engines are functions of particle/wall interactions and the Coefficient of Restitution (COR) is a fundamental property of these interactions. COR depends on impact velocity, angle of impact, temperature, particle composition, and wall material. In the first study, a novel Particle Tracking Velocimetry (PTV) / Computational Fluid Dynamics (CFD) hybrid method for measuring COR has been developed which is simple, cost-effective, and robust. A Laser-Camera system is used in the Virginia Tech Aerothermal Rig to measure microparticles velocity. The method solves for particle impact velocity at the surface by numerical methods. The methodology presented here characterizes a difficult problem by a combination of established techniques, PTV and CFD, which have not been used in this capacity before. The current study characterizes the fundamental behavior of sand at different impact angles. Two sizes of Arizona Road Dust (ARD) and one size of Glass beads are impacted on to 304-Stainless Steel. The particles are entrained into a free jet of 27m/s at room temperature. Mean results compare favorably with trends established in literature. This technique to measure COR of microparticle sand will help develop a computational model and serve as a baseline for further measurements at elevated, engine representative air and wall temperatures. In the second study, ARD is injected into a hot flow field at temperatures of 533oK, 866oK, and 1073oK to measure the effects of high temperature on particle rebound. The results are compared with baseline measurements at ambient temperature made in the VT Aerothermal Rig, as well as previously published literature. The effects of increasing temperature and velocity led to a 12% average reduction in total COR at 533oK (47m/s), a 15% average reduction at 866oK (77m/s), and a 16% average reduction at 1073oK (102m/s) compared with ambient results. From these results it is shown that a power law relationship may not conclusively fit the COR vs temperature/velocity trend at oblique angles of impact. The decrease in COR appeared to be almost entirely a result of increased velocity that resulted from heating the flow.