University of California, Los Angeles
The University of California , Los Angeles , is a Research I institution with extensive experiences in gas turbine-related research activities. The quality of our overall research and educational programs is reflected in the most recent rankings of graduate programs by US News and World Report: the School of Engineering and Applied Sciesce is ranked 13 th nationally the Mechanical Engineering program is assessed at 13 th , and the Aerospace Engineering program is 12 th . A sampling of our gas turbine and power generation-related expertise and activities – both research and educational – is described in detail below.
Research Activities and Facilities
Since September 2003, Jeff D. Eldredge has been as Assistant Professor in the Mechanical and Aerospace Engineering Department at UCLA. Dr. Eldredge conducted his doctoral work in Mechanical Engineering at the California Institute of Technology, and received his Ph.D. in 2002. After leaving Caltech, he served for two years as a Research Associate in the Department of Engineering at Cambridge University . His research activities at Cambridge were carried out under the auspices of the European PRECCINSTA program, a 21-partner consortium whose primary concern was the prediction and control of combustion instabilities in industrial gas turbines. Dr. Eldredge's experimental and theoretical investigation of mean-flow perforated liners was generally recognized as a highlight of this extensive program. As a member of the Energy Group at Cambridge , he collaborated on several projects involving combustion instabilities in laboratory-scale gas turbines. Much of this work involved a close relationship with Rolls-Royce, through the University Gas Turbine Partnership.
Dr. Eldredge has an extensive knowledge of the modeling and design of acoustic dampers. In addition, he has expertise in aeroacoustics and the development of particle-based numerical methods for simulation of flow/acoustic interactions. At UCLA, Dr. Eldredge leads a growing team of undergraduate and graduate research students conducting computational investigations of several problems in acoustics and fluid dynamics. His laboratory is composed of several dual Intel Xeon processor workstations and a library of computational tools. Recently, Dr. Eldredge has received a one-year grant from the University of California Energy Institute, under the Energy Science and Technology program for the project entitled “Passive Stability Control for Improving the Efficiency of Power Production in Industrial Gas Turbines”.
Acoustic experiments and modeling efforts carried out by Dr. Eldredge have identified a mean-flow perforated liner as an effective broadband absorber of incident sound. Its use as a suppressor of combustion oscillations in gas turbines, either on its own or as a complement to other passive devised such as a Helmoltz resonator, is the subject of current research efforts. The device is composed of a dense array of small circular holes through which a small mean flow is forced. Pressure fluctuations in the vicinity of the holes cause the unsteady shedding of vorticity from their rims. Through this process, acoustical energy in the vicinity of the liner is transformed into vertical energy, which is subsequently dissipated into a small amount of heat. This absorption mechanism can be extremely effective when the geometric parameters and mean liner flow are chosen in an optimal way. Modeling and experiments have demonstrated that such a liner system in a duct can absorb 83% of acoustic energy, as well as eliminate all reflected energy, over a large range of frequencies. Moreover, the small amount of air required to achieve such effective absorption should not be prohibitive of its use in a lean premixed combustor.
Additional gas turbine-related work is being conducted in the Combustion Research Laboratory (CRL) at www.seas.ucla.edu/combustion/ . |