Low noise cooling device

Abstract

A cooling device () using pulsating fluid for cooling of an object, comprising: a transducer () having a membrane adapted to generate pressure waves at a working frequency (f), and a cavity () enclosing a first side of the membrane. The cavity () has at least one opening () adapted to emit a pulsating net output fluid flow towards the object, wherein the opening () is in communication with a second side of the membrane. The cavity () is sufficiently small to prevent fluid in the cavity () from acting as a spring in a resonating mass-spring system in the working range. This is advantageous as a volume velocity (u) at the opening is essentially equal to a volume velocity (u') 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.