SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 1 - January 13, 2006

07 AIRCRAFT PROPULSION AND POWER
Includes primary propulsion systems and related systems and components, e.g., gas turbine engines, compressors, and fuel systems; and onboard auxiliary power plants for aircraft.

For related information see also 20 Spacecraft Propulsion and Power; 28 Propellants and Fuels; and 44 Energy Production and Conversion.

20060001862 CFD Research Corp., Huntsville, AL USA

Combustion LES Software for Improved Emissions Predictions of High Performance Gas Turbine Combustors

Black, David Lee; Meredith, Karl V.; Khosla, Sachin; Rani, Sarma L.; Smith, Clifford E.; Sep. 1, 2005; 125 pp.; In English; Original contains color illustrations Contract(s)/Grant(s): N00421-04-C-0002; Proj-CFDRC-8503/8 Report No.(s): AD-A440401; No Copyright; Avail.: CASI: A06, Hardcopy

Low emissions of CO, NOx, and unburned hydrocarbons (UHC) are a difficult challenge in the design of new military gas turbine combustors. Simulation tools that can predict emissions are needed to reduce the cost of producing improved, low emissions combustor designs. In this SBIR, CFD) Research Corporation (CFDRC) continued to develop combustion Large Eddy Simulation (LES) techniques to create a high fidelity tool for predicting emissions. The LES code was improved by the development and implementation of a new multi-step assumed PDF method that accounts for more detailed kinetics with turbulent chemistry interactions. This new method enables efficient turbulent combustion CFD) calculations for both steady state Reynolds Averaged Navier Stokes (RANS) and LES with multi-step global mechanisms. Tabulation methods were implemented and tested for improved computational efficiency. Improvements to the existing combustion models and inlet boundary conditions for LES were also performed. In addition to the new turbulent combustion models, the capability to generate the necessary global mechanisms from detailed reaction mechanisms was developed. The final code was validated against benchmark experimental data, and applied to the Rolls-Royce JSF combustor. Validation cases included both premixed and diffusion flames covering a broad range of flame conditions. Although much progress was made in this Phase II effort, continued work is needed to make the new multi-step assumed PDF model robust and practical. In particular, a new solver for the species transport equations needs to be implemented to reduce run times by a factor of two or more. DTIC

Combustion; Combustion Chambers; Gas Turbines; Hydrocarbons

20060002378 General Electric Global Research, Niksayuna, NY, USA

Wear Prediction of Strip Seals Through Conductance

Turnquist, Norman; Ghasripoor, Farshad; Kowalczyk, Mark; Couture, Bart; 2004 NASA Seal/Secondary Air System Workshop, Volume 1; October 2005; 15 pp.; In English; See also 20060002371; Original contains color illustrations; No Copyright; Avail.: CASI: A03, Hardcopy

Test data indicate strong influence of conductance in rub behavior of strip seals at speeds in excess of 50 m/s. Material strength appears to have little effect on rub for strip seals with aspect ratios \h0.07.

A predictive model is established as a tool to help select the strip material and in design of the strip.

Best strip material selection and design would extend the strip seal's ability to severe rub events beyond the abradable thickness. Derived from text

Seals (Stoppers); Mechanical Properties; Wear; Abrasion; Aspect Ratio

Source: NASA.