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Effective Processes to Manufacture Advanced Combustion Liners with Shaped Film Cooling Holes for Gas Turbine Engines


OBJECTIVE: Develop and validate advanced, low cost manufacturing methods such as water jet drilling or Direct Metal Laser Sintering (DMLS) to effectively manufacture advanced combustor liners with angled and shaped effusion film cooling holes. DESCRIPTION: Small angled holes (aka effusion) are used to provide effective film cooling on gas turbine combustor liners, comprised of thermal barrier coated (TBC) sheet metal. The potential exists to shape effusion cooling holes to further improve the film cooling effectiveness. Significant reductions in liner temperatures, a direct result of improving the film cooling effectiveness, can be used to enable higher component life or enable higher power density/ fuel-efficient engines. In addition, the improved film cooling effectiveness can significantly reduce the hot-side TBC temperature such as to inhibit Calcia-magnesia-alumina-silicate (CMAS) degradation of the TBC. Current effusion holes are typically laser drilled into the liner. However, the laser drilling process does not lend itself to shaped-hole drilling. Recent developments in manufacturing technology, such as Water Jet Drilling and Direct Metal Laser Sintering, offer potential to provide an effective, low cost means of manufacturing these shaped effusion cooling holes. The objective of this topic is to develop and validate advanced, low cost manufacturing methods to effectively manufacture advanced combustor liners with angled and shaped effusion film cooling holes for application to future Army turboshaft engines. The small business is encouraged to work with and establish a clear transition path with a turbine engine manufacturer. PHASE I: Preliminary design and evaluation of proposed process to ascertain the following: 1) feasibility of manufacturing shaped effusion holes in a combustor, 2) to characterize types of effusion hole shapes that can be effectively manufactured to maximize film cooling effectiveness and 3) to produce several coupons with a representative pattern for film cooling effectiveness assessment. PHASE II: Proceed to fabricate parts based upon the phase I screening for assessment by combustor rig testing at relevant gas turbine condition with further refinement of the effusion shapes in order to advance the technology to a technical readiness level (TRL) of 5. PHASE III: The optimized, shaped-hole cooling process shall be applied to a combustor for full engine test validation to TRL 6. The phase III effort will provide sufficient technology maturity to allow transition to an engine engineering, manufacturing, and development (EMD) program. REFERENCES: 1. Will F. Colban, Karen A. Thole, and David Bogard,"A Film-Cooling Correlation for Shaped Holes on a Flat-Plate Surface,"Journal of Turbo-machinery, Volume 133, Issue 1, 011002 (11pages), January 2011 2. Jong S. Liu, Malak F. Malak, Luis A. Tapia, Daniel C. Crites, Dhinagaran Ramachandran, Balamurugan Srinivasan, Gopalsamy Muthiah, and Jyothishkumar Venkataramanan,"Enhanced Film Cooling Effectiveness With New Shaped Holes,"ASME Turbo Expo 2010, Volume 4, Heat Transfer, pp 1517-1527, June 14 2010 3. M. Hashish & J. Whalen,"Precision Drilling of Ceramic-Coated Components with Abrasive-Waterjets", Journal Eng. Gas Turbines Power, Volume 115, Issue 1, pp.148-154, January 1993 4. R. Kovacevic, M. Hashish, R. Mohan, M. Ramulu, T. J. Kim and E. S. Geskin,"State of the Art of Research and Development in Abrasive Waterjet Machining"J. Manuf. Sci. Eng., Volume 119, Issue 4B, pp. 776, November 1997 5. W.K. Chiu and K.M. Yu,"Direct Digital Manufacturing of Three-Dimensional Functionally Graded Material Objects,"Computer-Aided Design, ISSN 0010-4485, Volume 40, Issue 12, pp. 1080-1093, December 2008.
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