An experimental and numerical investigation of forced convection in high porosity aluminum foams subjected to jet array impingement in channel-flow. (March 2020)

• Record Type: Journal Article
• Authors: Singh, Prashant; Nithyanandam, Karthik; Mahajan, Roop L.
• Is Part Of: International journal of heat and mass transfer. Volume 149(2020)
• Publication Date: 2020-03
• Subjects: Metal foam -- Jet impingement -- Forced convection -- Thermal management; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2019.119107
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Experimental and numerical study on array jet impingement on foams flushed with jets presented. Different pore-densities 10, 20, 40 ppi and jet configurations x / d = 2, 3 and 5 studied. Largest pore density (40 ppi) and largest open area ratio jet configuration ( x / d = 2) yield highest heat dissipation. Abstract: This paper reports an experimental and numerical investigation on flow and thermal transport in high porosity aluminum foams (ε~0.94–0.96) placed in a channel of square cross-section and subjected to jet array (5 × 5) impingement. The plate issuing the jets was flushed with the metal foam face. Experiments were conducted for three different values of jet-to-jet spacing (x/ dj =y/ dj ) of 2, 3 and 5, and three foam samples with pore-densities 10, 20, and 40 PPI (pores per inch). Values of steady-state heat transfer rate and pressure drop were calculated for Reynolds number (based on channel hydraulic diameter and channel inlet velocity) ranging from 2500 to 13, 500. The main findings are as follows: first, for all the test runs, the impingement configurations had higher heat transfer rate, h, compared to that for the baseline configuration of metal foams in a channel flow. Second, for all values of the jet-to-jet spacing, an increase in pore-density was accompanied by an increase in heat transfer. The enhancement ( h / h 0 ) varied between 26 and 48, with the highest gain observed for the widest jet (x/d=2) and the highest pore density (40 ppi) configuration, where h0 is the heat transfer coefficient for developed turbulent flow in a circular duct. The numerical computations reveal interesting recirculating flow structures immediately downstream of the jet exits and the extent of flow penetrating in the foam. Collectively, these flow patterns play a dominant role in determining the volume of metal foam volume participating in the thermal transport and the net convective heat transfer rate.