Coupled Transpired and Discretely Injected Films

NASA, and all users of turbomachinery, continuously requires improvements in engine durability and efficiencies. As combustion engineers push turbine inlet temperatures to new extremes, cooling designers are faced with increasing heat loads and less available coolant usage. Surface cooling techniques such as film cooling have proven invaluable in this quest. Films generated by forcing the coolant to bleed through a porous substrate have been shown to perform substantially better than discrete film injection in a thermal sense. However, the associated aerodynamic penalties limit the application. On the other hand, discretely injected films have drawbacks as well, including non-uniform coolant profiles significant mixing with the hot working fluid, lowering their effectiveness. Spectral Energies, LLC and the University of Central Florida propose a novel, low risk approach to surface cooling wherein traditional discrete film holes are embedded within a transpiring porous strip. The motivation behind this approach is multi-faceted, with the ultimate goal of developing a cooling arrangement which possesses the thermo-mechanical benefits of a transpired film, the aerodynamic benefits of discrete film injection, and mixing characteristics that are some compromise of the two.

In addition to NASA applications, all users and developers of gas turbines will benefit from the ability to achieve improved heat load handling and durability. This includes gas turbines for propulsion (the airline and marine industries) as well as for power generation. The public will then directly benefit through reduced electricity and travel costs. Additionally, as the private sector is now heavily involved in the development of space technologies, high efficiency and durable hot gas components will be applicable to a large number of up and coming private industries.  

NASA is a direct user and developer of turbomachines for various applications, primarily for propulsion. As improved efficiency and improved durability are the goals of NASA researchers, the successful implementation of this technology will provide a direct method of achieving both. The proposed innovation will provide increases in efficiency and reductions in fuel burn, through the ability to handle increased working gas temperatures with minimal coolant usage; and durability through the reduction of hot streaks associated with traditional film cooling methods. Additionally, applications such as the film cooling of rocket nozzles will also benefit from the successful implementation of this technology.

This is early/mid-stage (TRL 6) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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