| Popis: |
Over the past decade, Arthur Lefebvre participated each year in the “Gas Turbine Short Course” in Irvine, a course that he conceived and previously taught at Purdue. Before or after the short course, Arthur each year engaged the UCI combustion graduate students and discussed their research projects, provided insight and guidance based on his decades of experience. The study reported herein is one such example. The paper discusses results from research conducted in 2000 that was watched closely by Arthur during his annual visits to Irvine. The motivation for this work arises from issues associated with premixers for gas turbines. As inlet temperatures increase, the question is raised as to whether the reaction will be disgorged from the mixer and stabilize on wall perturbations associated with joints and fasteners. The current study systematically studies the tendencies for such wall perturbations to anchor a reaction using a flow tube that can provide the velocities, temperatures, pressures, and perturbations representative of those found in practical engine applications. A sudden step expansion perturbation geometry was the focus of the current effort. Fuel and velocity distributions within the flow tube were measured. A statistically designed experiment was developed and conducted in order to identify the key geometric and operational factors affecting flameholding. Arthur’s experience and expertise in the area of flameholding led to a natural interest in this project as it looked at flameholding in the limiting cases of small geometries (really geometry perturbations vs flameholders), whereas the work he had done emphasized relatively large stabilizers. Indeed, the focus of his effort was to design system to hold flame, whereas the present study was seeking to answer the question of “at what dimension will flame no longer be held”? As a consequence, Arthur saw an old problem being looked at from a different perspective, which, not surprisingly, was intriguing. |
