Carnegie Mellon University
The Department of Mechanical Engineering at Carnegie Mellon University has extensive capabilities and facilities associated with gas turbine research. Programs currently underway include combustion modeling, particle sizing, atomization and sprays, heat transfer and fluid mechanics, and vibration.
Modeling of Combustion and Emissions
Two- and three-dimensional numerical studies are being performed to analyze the flow field, combustion, and pollutant formation in lean, premixed prevaporized (LPP) and rich-burn, quick-quench, lean-burn (RQL) gas turbine combustors. These studies include a two-equation model of turbulence, kinetics and mixing-controlled combustion models, the extended Sel'dovich mechanism for nitric oxide formation. They also include a discrete droplet model and a hybrid Eulerian-Lagrangian formation, which solves the gas phase equations in Eulerian coordinates, whereas groups of droplets are followed in Lagrangian coordinates.
Atomization and Sprays
Atomization and Spray characteristics of Newtonian and non-Newtonian liquids are studied in specially designed spray chambers. Co-axial, swirl, and multi-hole atomizers are tested. Measurements of drop size velocity, number density, and momentum flux are measured by an Aerometric Phase Doppler Particle Analyzer (PDPA). Traverses are made in the axial and radial directions to provide histograms of size and velocity distributions and size-velocity correlations. Detailed measurements of mean and fluctuating velocity in the gas stream are measured by a TSI two-component laser Doppler Velocimeter from which shear stress and kinetic energy of turbulence is determined. A Malvern laser diffraction instrument measures mean size and size distribution of droplets in a cloud of droplets. A Greenfield digital image analyzer uses a CCD camera to capture images in the breakup and spray regions for analysis of droplet size and ligament shapes. High-speed microphotography is used for global characterization of sprays, including spray angle, penetration, and breakup of liquid jets and ligaments into droplets. Detailed studies and analyzers have been made sprays for: 1) the space shuttle engines, burning liquid oxygen and gaseous hydrogen; 2) coal wafer slurries, polymers, and non-Newtonian liquids; 3) diesel jets; and 4) industrial applications involving combustion, cooling and liquid metal sprays.
Cooling of Turbine Components
A variety of experimental and numerical studies in progress are directed towards obtaining fundamental understanding and design criteria of convective cooling of components in high-performance turbine engines. Ongoing research activities address internal cooling with serpentine passages, geometric effects of rib-turbulator, pin-fin array heat transfer, tip leakage flow and heat transfer, film cooling, and two-phase mist cooling. Both experimental measurements and numerical modeling are being performed. Measurement techniques used include conventional thermal methods, liquid-crystal surface coating, thermographic phosphor, infrared thermography and subliming mass transfer technique. Numerical techniques used include pressure-based and density-based algorithms as well as Chimera grids. One of the most recent efforts is to develop a multi-dimensional thermal imaging system based on laser-induced, rare-earth doped phosphorescence. Such a technique is partially effective for planar temperature sensing under rapid transient and/or high temperature conditions.
GUIde Consortium on the Forced Response of Bladed Disks
The GUIde Consortium on the Forced Response of Bladed Disks was established in early 1991 when a number of companies that produce gas turbines joined with Carnegie Mellon and Purdue to form a partnership that would result in improved technology for predicting and controlling blade vibration in rotating machinery. The Consortium was formed in order to provide a fully coordinated approach for developing new methods of predicting and controlling blade vibration utilizes the pooled resources. The GUIde acronym embodies this Government agencies, Universities, and Industry working together to develop and enhanced vision of how to obtain their mutual goals. Currently, projects in forced response are being sponsored by the Consortium at CMU, Purdue , Ohio State, University of Michigan , and UTRC.
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