Computational Fluid Dynamics (CFD) Tools for the Management of Bulk Residual Stress

ABSTRACT: Development and validation of a CFD method for determining heat flux rates during quenching of aircraft components is proposed. Current methods of managing the bulk residual stresses of machined aircraft forgings rely on experimental determinations of quenching heat fluxes that are costly, time-consuming, and subject to several types of errors. The proposed Phase I scope of work includes the development of several novel routines for the simulation of all modes of boiling heat transfer as well as the transition between these modes. Initial validations will be based on published data for each portion of the simulation method. The final validation will be based on new data collected on a representative part in a typical quench facility. Analysis of the quench data will include calculation of the experimentally determined heat fluxes and prediction of residual stresses based on CFD and test-based heat flux rates. Completion of this effort will establish the feasibility of developing a practical CFD-based tool for management of bulk residual stress. BENEFIT: A well developed CFD tool will provide more accurate and complete data, and will avoid the time and cost involved in manufacturing prototype parts for use in heat flux determinations. The higher quality data will be useful in developing improved manufacturing techniques, which will allow for the development of near-net shape forgings techniques. These improvements will directly impact the buy-to-fly ratio for these parts (the ratio of the forged weight to the final part weight) providing a direct reduction in manufacturing costs. In addition to extensive applications within the military and commercial aerospace communities, the proposed tool could be widely applied within the broader manufacturing industries. Data from 2006 suggests that the size of the commercial US heat treating market is greater than $20 billion. Improvement in the quench quality for the high value end of that market will represent a significant improvement in quality along with a reduction in scrap and rework rates.