Synthetic jet cooling part I: overview of heat transfer and acoustics

The paper deals with an overview of the principles of heat transfer and acoustics related to a promising alternative for fans: synthetic jet cooling. After a short discussion of the benefits, the background and the principles underlying the physics are treated. The problems with optimisation through numerical analysis are highlighted. An accompanying paper discusses the experimental results in terms of heat transfer and noise for a special embodiment: an acoustic dipole cooler

Synthetic jet cooling part II: Experimental results of an acoustic dipole cooler

The paper discusses experimental results for a typical embodiment of synthetic jet cooling technology: an acoustic dipole cooler comprised of a standard loudspeaker in a housing provided with two pipes. A transient measurement set up is used to measure the average heat transfer coefficient based on cooling a 5*5 cm2 metal plate. Heat transfer and noise results are presented for a range of frequencies, pipe lengths and diameters. The results are compared with a standard 60*60 mm fan. It is concluded that, at least for the cases studied, the synthetic jet is superior on all fronts: heat transfer performance, noise level and dissipated powe

Low noise cooling device

A cooling device (1) using pulsating fluid for cooling of an object, comprising: a transducer (2) having a membrane adapted to generate pressure waves at a working frequency (fw), and a cavity (4) enclosing a first side of the membrane. The cavity (4) has at least one opening (5) adapted to emit a pulsating net output fluid flow towards the object, wherein the opening (5) is in communication with a second side of the membrane. The cavity (4) is sufficiently small to prevent fluid in the cavity (4) from acting as a spring in a resonating mass-spring system in the working range. This is advantageous as a volume velocity (u1) at the opening is essentially equal to a volume velocity (u1') at the second side of the membrane, apart from a minus sign.; Thus, at the working frequency the pulsating net output fluid can be largely cancelled due to the counter phase with the pressure waves on the second side of the membrane resulting in a close to zero far-field volume velocity. Thus a low sound level is achieved, at a low cost, without requiring mechanical symmetry

Synthetic jet cooling using asymmetric acoustic dipoles

In two earlier papers the principles and experimental results have been discussed for a typical embodiment of synthetic jet cooling technology: an acoustic dipole cooler comprised of a standard loudspeaker in a housing provided with two pipes. The current paper shows experimental and numerical results for another type: the asymmetric dipole. Basically, this type consists of a loudspeaker with a minimal volume attached to it with one or more holes with or without pipes. Results for driving power and noise are presented for a number of actuators covering a large parameter space: frequency, pipe dimensions and driving voltage were varied over a large range. A relatively simple acoustic model extended to include separation losses matched the experimental results very well. The results indicate promising heat transfer performance with minimal noise combined with a large degree of freedom

Remote cooling by combining heat pipe and resonator for synthetic jet cooling

This invention relates to thermal management for removing heat generated by a heat source (110). This is done by a combination of a heat conducting member (120), which is thermally connected to the heat source in one end and to a remotely arranged heat sink (130) in the opposite end, and a synthetic jet actuator (140). The synthetic jet actuator is arranged to provide active cooling directly onto the heat source by generating and directing an air flow towards the heat source. The synthetic jet actuator comprises a resonator cavity housing (150) and an oscillating member (160). The oscillator member is arranged at least partly inside said resonator cavity. The combination of the heat conducting member and the synthetic jet actuator provides a highly efficient cooling

Remote cooling by combining heat pipe and resonator for synthetic jet cooling

This invention relates to thermal management for removing heat generated by a heat source (110). This is done by a combination of a heat conducting member (120), which is thermally connected to the heat source in one end and to a remotely arranged heat sink (130) in the opposite end, and a synthetic jet actuator (140). The synthetic jet actuator is arranged to provide active cooling directly onto the heat source by generating and directing an air flow towards the heat source. The synthetic jet actuator comprises a resonator cavity housing (150) and an oscillating member (160). The oscillator member is arranged at least partly inside said resonator cavity. The combination of the heat conducting member and the synthetic jet actuator provides a highly efficient cooling