Wayne State University
Several experimental and theoretical research programs related to gas turbine combustor and automotive I.C. engine applications are in progress at WSU. These projects are sponsored by NASA, Army, NSF, Detroit Edison, automotive and gas industries. Main research faculty involved are Professors Naeim A. Henein, Jerry C. Ku, M.-C. Lai and Robert Piccirelli. Main test instrumentations include two-dimensional LAD and PDPA systems, high-speed movies and video systems, pulsed dye laser system, intensified CCD camera and diode array systems, and emission cart. Main test facility includes spray combustion and I.C. engine cells. The following is a summary of the on-going research program:
Venturi Tube Nozzle Effects on Fuel Atomization, Evaporation and Mixing with Air
The multiple venturi tube nozzles are usually employed for the flame tube experiments. They are designed with as many injection sources as practical, but without fuel impinging on tube or linear walls, and with no wakes where fuel could be entrained and possibly exceed auto ignition limits. These configurations has distinct advantages as a fuel/air preparation system for advanced gas turbine applications. Therefore, a combination of experimental and analytical study of the processes are carried out to characterize and model the processes directly.
The experimental techniques are all laser-based, including PDPA and Planar Laser-Induced Fluorescence (PLIF) visualization of the evaporating fuel sprays. Both could flow atomization experiments and pressurized heated flow experiments are carried out. Test parameters consider a wide range of flow conditions and geometric design. A multidimensional modeling of the spray processes is performed using a modified version of the KIVA-II code. Prediction of spray breakup, droplet dispersion and fuel evaporation history are compared with experimental data directly. The results of this study are being used in the system design and practical applications.
Rapid Mix Concepts for Low Emission Combustors
Different low emission combustor concepts utilizing rapid mixing, among which include the cyclonic (tangential mixing) and the RQL (radial mixing) combustors, are being studied both numerically and experimentally. The research goal is to simulate the overall physical and chemical processes and to develop a multidimensional design tool for these combustors.
The swirling/recirculation flow field of the cyclonic combustors generate intensive turbulent mixing and substantial ICPR. Therefore, it greatly enhances flame stabilization, completing of combustion, and uniformity of temperature and concentration distributions. Combustion tests have shown that lean, premixed, gas-fired cyclonic combustors can operate stably under very lean conditions and generate ultra-low NO x , CO , and total hydrocarbon (THC) emissions. The successful combustor operation of the cyclonic combustor strongly depends on the geometric design of the tangential nozzle flow and the orifice.
n the other hand, the quick-mix section of a tubular RQL combustor which utilizes staged firing is essentially a radial mixer. Previous experience with rich/lean combustion for heavy fuel applications clearly showed the sensitivity of the quick-mix section to the overall emission. It is the performance of quick-mix step, and achieving it at the cost of minimum pressure loss, which holds the key to a successful RQL combustion. The optimal momentum flux ratio is found to strongly depend on the mixer geometry including different dilution holes designs, the number of injection holes, slot aspect ratios, slot orientation, and the effects of swirl. |