Session: 11-15-01: Fluid Problems in Energy Systems

Paper Number: 166585

Flow Dynamics Analysis of Air Jets on Porous Surfaces 

Metallic foams, particularly open-cell structures, offer excellent heat transfer capabilities due to their high permeability, specific surface area, and thermal conductivity. Their porous nature allows fluid flow, enhancing both convective and conductive heat exchange. By adjusting porosity and pore size, their performance can be optimized for applications such as heat exchangers, cooling systems, and energy-efficient industrial processes.

Air jets impinging on metallic foams presents unique properties, in terms of heat transfer and air flow dynamics, which enhance heat transfer coefficient, improving cooling and heating in several high density thermal applications. However, the complexity of the jet flow dynamics over metallic foams makes this research area challenging.

In this context, the present work investigates the flow dynamics of air jets over target surfaces made up of metallic foams with different porosity and pore size. An experimental setup was developed for measuring flow velocity using a 2D-PIV system. The Particle Image Velocimetry is an experimental technique that allows characterizing the flow dynamics of single and multiple jets, allowing to capture the development of complex turbulent structures. The study focuses on five aluminum metallic foams, with different porosity and pore sizes, in order characterize the effect of these properties on the flow dynamics. The experimental setup comprises a fan, a honeycomb structure, an acrylic tube, a jet generator plate and an Aerotech Concept smoke generator. The air flow is seeded by the smoke generator with oil droplets inside a stabilization chamber installed at the outlet of the centrifugal fan. The seeding particles are obtained through the atomization of Concept smoke oil 135. The droplet mean diameter was measure by a laser diffraction technique and was observed to be between 1 and 5 μm. To ensure a uniform mixture between the air flow and the seeding particles, the seeded flow passes through the honeycomb structure to straighten the flow and a series of metallic meshes that stabilize the flow. The flow is subsequently directed into a stabilization chamber and into the ambient through the jet generating plate. This is made up of multiple 5 mm diameter circular orifice nozzles that induce multiple jets impacting on the metal foams. The pattern and number of orifices distribution can be adjusted by changing the nozzle plate. The nozzle to target surface can be adjusted. The flow structures and interactions will be analyzed by the 2D PIV system on the metallic foams and the results will be presented, characterizing the effect of pores and porosity on the jet flow dynamics.

Presenting Author: Jose Teixeira Universidade do Minho

Presenting Author Biography: Jose Teixeira is Professor of Fluid Mechanics and Heat Transfer at the University of Minho, Portugal

Authors:

Erany Constantino Universidade do Minho
Flavia Barbosa Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial
Jose Grilo Universidade do Minho
Senhorinha Teixeira Univrsidade do Minho
Jose Teixeira Universidade do Minho