Session: 11-42-01: Heat and Mass Transfer in Heating, Cooling, and Power Systems

Paper Number: 113638

113638 - Experimental Analysis of the Effect of Fluidic Oscillator Geometry on Heat Transfer Performance 

Fluidic oscillators have increasingly captured the attention of the scientific community and industry, since, due to their unique properties, they can be used in several areas such as acoustics, fluid mechanics, and heat transfer, amongst others. This device can convert a stable jet into an oscillating jet from the inherent instability of the fluid flow. Thus, the fluidic oscillator creates an oscillating jet, with different frequencies, without the application of external forces or moving devices. In that sense, it is most attractive for the manipulation of the fluid flow without any additional equipment, reducing the costs of several engineering applications and processes. Regarding their advantages, this study consists of the experimental analysis of the geometric, kinematic, and dynamic parameters that affect the performance of oscillating jets. Based on this analysis, the geometry of a Double Feedback Loop (DFO) oscillator was defined and a prototype was designed and constructed. The appropriate materials and manufacturing processes were carefully chosen for its construction and the design parameters were selected based on the factors and levels that mainly influence the dynamics of the jet flow according to an extensive literature review. From this analysis, the geometric variables considered as the most relevant were defined, as well as the flow properties in terms of Mach and Reynolds numbers. In this context, the widths of the inlet and outlet nozzles, the inlet and outlet of the feedback channel, the mixing chamber inlet and outlet, and the strangulation width are the geometrical parameters considered in this study. To analyze the effect of these variables on the flow dynamics, an experimental setup was designed and constructed allowing the variation of the air flow rate. To visualize the flow oscillation, seeding particles are introduced into the system. This seeding consists of olive oil droplets with a diameter varying between 1-3 μm, which is appropriate for the study of turbulent air jets, as they follow the smaller time scales. Besides the analysis of the jet flow dynamics, the heat transfer rate was measured using a heat flux sensor and the optimal design was defined using a Design of Experiment approach, based on Taguchi’s method. From this experimental analysis, the performance of the oscillating jet is characterized and compared with other similar forced convection techniques used for cooling applications. These results present promising conclusions regarding the implementation of fluidic oscillators, increasing their implementation in heat transfer processes at a reduced cost.

Presenting Author: José C. F. Teixeira University of Minho

Presenting Author Biography: JOSÉ CARLOS FERNANDES TEIXEIRA. Completed the Título de Agregado by Universidade do Minho in Jan 15, 2005; PhD in Chemical Engineering in 1989 by the University of Birmingham (UK) and the Licenciatura in Engenharia Metalomecânica in September 30, 1983 by the Universidade do Minho. He is Full Professor at the Universidade do Minho. Published 48 articles in journals. Has 13 section of books and 9 book. Organized 9 events, including the ECOS in 2018. Supervised 11 PhD theses e co-supervised 4. Has also supervised nearly 100 master theses. Participates or participated as Principal investigator in 15 projects and Researcher in 8 projects. Works in the area of Engineering and Technology with emphasis on Mechanical Engineering. In his curriculum Ciência Vitae the most frequent terms in the context of scientific, technological and artistic-cultural output are: Fluids; Energy; Heat Transfer. His scientific research area is within the field of Transport Phenomena. In this context, one of the main fields concerns the application of non intrusive methods in fluid mechanics. Therefore, in multiphase flows, laser diffraction based techniques and the Phase Doppler Anemometry have been used in various flow configurations either open (sprays) or closed (pipe flows). On the other hand, the Laser Doppler Anemometry and PIV habe been used for velocity measurements in single phase flows, mostly in environmental related applications. Another field of interest is the application of Heat Transfer techniques in energy conversion and processing technologies. Finally, in collaboration with the Numerical Methods Group in the Production Engineering Department, a code for the numerical simulation of the non isothermal flow of complex fluids has been developed. This area has been extended through a collaboration with the University of Ontario, Canada, developing parallel computing techniques in Fluid Flow simulation. Currently he has been involved in a collaborative project with Bosch CarMultimedia to develop computing tools to simulate the manufacturing of PCB's. He has been instrumental is developing an area of research in Biomass applications. It is focused in small scale technologies for heat. A competence network has been funded by the Portuguese Innovation Agency (AdI). He his member of the scientific committee of the Renewable Heat and Cooling EU platform.

Authors:

Rita C. S. Gomes University of Miho
Flavia V. Barbosa University of Minho
Erany Constantino University of Minho
Senhorinha C. F. Teixeira University of Minho
José C. F. Teixeira University of Minho