SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 4 - February 24, 2006

28 PROPELLANTS AND FUELS
Includes rocket propellants, igniters, and oxidizers; their storage and handling procedures; and aircraft fuels.

For nuclear fuels see 73 Nuclear Physics.

For related information see also 07 Aircraft Propulsion and Power; 20 Spacecraft Propulsion and Power; and 44 Energy Production and Conversion.

20060005844

Validation and Enhancement of Comprehensive Combustion Modeling and Simulation

October 2005; 34 pp. Contract(s)/Grant(s): NCC3-925; No Copyright; Avail.: CASI: A03, Hardcopy

The three-dimensional, viscous, turbulent, reacting and non-reacting flow characteristics of a model gas turbine combustor operating on air/methane are simulated via an unstructured and massively parallel Reynolds-Averaged Navier-Stokes (RANS) code. This serves to demonstrate the capabilities of the code for design and analysis of real combustor engines.

The effects of some design features of combustors are examined. In addition, the computed results are validated against experimental data. The numerical model encompasses the whole experimental flow passage, including the flow development sections for the air annulus and the fuel pipe, twelve channel air and fuel swirlers, the combustion chamber, and the tail pipe. A cubic non-linear low-Reynolds number K-e turbulence model is used to model turbulence, whereas the eddy-breakup model of Magnussen and Hjertager is used to account for the turbulence combustion interaction.

Several RANS calculations are performed to determine the effects of the geometrical features of the combustor, and of the grid resolution on the flow field. The final grid is an allhexahedron grid containing approximately two and one half million elements. To provide an inlet condition to the main combustion chamber, consistent with the experimental data, flow swirlers are adjusted along the flow delivery inlet passage.

Fine details of the complex flow structure such as helical-ring vortices, recirculation zones and vortex cores are well captured by the simulation consistent with the experimental results, the computational model predicts a major recirculation zone in the central region immediately downstream of the fuel nozzle, a second recirculation zone in the upstream corner of the combustion chamber, and a lifted flame. Further, the computed results predict the experimental data with reasonable accuracy for both the cold flow and for the reacting flow. It is also shown that small changes to the geometry can have noticeable effects on the combustor flowfield. Author

Combustion Chemistry; Mathematical Models; Fuel Combustion; Simulation

Source: NASA