An experimental study on thermoacoustic instabilities in syngas-air premixed impinging jet flames

Impinging jet is widely used in both traditional industrial and new high-tech fields. High efficiency heat transfer in impinging jet cooling makes it an important method for heat transfer enhancement, in particular in cooling of electronic devices with high heat density. This paper presents an experimental study of heat transfer by an impinging circular water jet. A Constantan foil with the size of 5 mm × 5 mm was used to simulate a microelectronic chip with heat generated by passing an electrical current through the foil. A high heat flux over 106 W/m2 was achieved. The surface temperature was measured by a thermocouple glued onto the back surface of the foil. Both a free surface jet and a submerged jet were investigated. Effect of the nozzle-to-surface spacing as well as the jet speed at the exit of the nozzle on cooling was examined. By positioning the jet away from the center of the heating foil surface, the radial variation of the heat transfer coefficients over the foil was also investigated. Quantitative heat transfer data have been obtained and analyzed.

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Numerical and Experimental Study of Flow and Convective Heat Transfer on a Rotor of a Discoidal Machine with Eccentric Impinging Jet

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4044207 ◽

2019 ◽

pp. 1-29

Author(s):

Chadia Haidar ◽

Rachid Boutarfa ◽

Mohamed Sennoune ◽

Souad Harmand

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Steady State ◽

Convective Heat Transfer ◽

Convective Heat ◽

Air Flow ◽

Impinging Jet ◽

Rotating Disk ◽

Reynolds Numbers ◽

Air Jet

This work focuses on the numerical and experimental study of convective heat transfer in a rotor of a discoidal the machine with an eccentric impinging jet. Convective heat transfers are determined experimentally in steady state on the surface of a single rotating disk. The experimental technique is based on the use of infrared thermography to access surface temperature measurement, and on the numerical resolution of the energy equation in steady-state, to evaluate local convective coefficients. The results from the numerical simulation are compared with heat transfer experiments for rotational Reynolds numbers between 2.38×105 and 5.44×105 and for the jet's Reynolds numbers ranging from 16.5×103 to 49.6 ×103. A good agreement between the two approaches was obtained in the case of a single rotating disk, which confirms us in the choice of our numerical model. On the other hand, a numerical study of the flow and convective heat transfer in the case of an unconfined rotor-stator system with an eccentric air jet impinging and for a dimensionless spacing G=0.02, was carried out. The results obtained revealed the presence of different heat transfer zones dominated either by rotation only, by the air flow only or by the dynamics of the rotation flow superimposed on that of the air flow. Critical radii on the rotor surface have been identified

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