Patent ID: 8123502

Claim:
A fluid pump comprising: one or more actuators; two end walls; a side wall; a cavity which, in use, contains fluid, the cavity having a substantially cylindrical shape bounded by the end walls and the side wall; at least two apertures through the cavity walls, at least one of which is a valved aperture; wherein the cavity radius, a, and height, h, satisfy the following inequalities: a ⁢ h is greater than 1.2; and h 2 a is greater than 4×10 −10 m; and wherein, in use, the one or more actuators cause oscillatory motion of one or both end walls in a direction substantially perpendicular to the plane of the end walls; whereby, in use, the axial oscillations of the end walls drive radial oscillations of fluid pressure in the cavity; wherein the cavity radius, a, also satisfies the following inequality: k 0 · c_min 2 ⁢ ⁢ π ⁢ ⁢ f < a < k 0 · c_max 2 ⁢ ⁢ π ⁢ ⁢ f , where c_min is 115 m/s, c_max is 1970 m/s, f is the operating frequency and k 0 is a constant (k 0 =3.83); and wherein, in use, the motion of the driven end wall(s) and the pressure oscillations in the cavity are mode-shape matched and the frequency of the oscillatory motion is within 20% of the lowest resonant frequency of radial pressure oscillations in the cavity.