Novel flow control strategies for heat transfer enhancement in a minimal array of impinging jets

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PI: Naguib, AhmedProposal Number: 1603720The goal of the proposed research is to investigate the flow behavior of arrays of jets used in several engineering applications - most prominent of which is turbine blade cooling in gas turbine engines. In addition, cooling effects that the flow from the jets generates when it impinges on a surface will be studied. The proposal is motivated by the significance of impinging jets for heating, cooling and drying in many industrial processes and engineering devices. A particularly significant application is turbine blade cooling in gas turbine engines, where effective cooling can have a strong favorable impact on engine efficiency, causing substantial reduction in fuel consumption and pollution. The goal of the proposed work is to study the potential for significant augmentation of heat transfer in impinging jet arrays using active flow control strategies. The control strategies, which are conceived based on detailed understanding of the spatio-temporal relationship between the jet's vortical structures and the surface heat flux, will be implemented using plasma actuators mounted around the lips of axisymmetric jets arranged in an inline array. The array size is kept to a minimum of three to enable reproduction of fundamental jet-jet interaction phenomena while avoiding the complexity of large-size arrays. The study will employ time-resolved flow visualization and phase-locked PIV measurements to capture flow-field information simultaneously with measurements of the average convection heat transfer coefficient using temperature-sensitive paint, and spatio-temporal wall heat flux information using thin-film gage arrays. Data will be acquired for a range of parameters including jet-to-impingement-wall spacing, jet-to-jet spacing, Reynolds number, control strategies/parameters, and crossflow presence. This work will result in the education of a graduate student and the involvement of undergraduate students in research, who will also be actively involved in the dissemination of the research to summer high-school students. The graduate and undergraduate researchers will be recruited from underrepresented groups with the aid of existing programs at Michigan State University. New course content will be developed on experimental fluid dynamics that will integrate results from this research.