US Patent 7908855 Fluidic oscillator

The invention relates to fluidic oscillators including compressed gas driven pumps and liquid piston and thermoacoustic heat engines and heat pumps in which the intention is to generate large amplitude oscillations by eliminating the dependence of the oscillations on inertia. According to the principle embodiment represented by circuit 200 pressure or temperature variations 27′ drive pressure variations in vessel 11′ causing a flow of further working fluid between vessel 11′ and load 12′ wherein useful work is consumed. Said flow varies out of phase with said pressure variations in vessel 11′ by a first phase angle determined by inter alia the dissipative load 12′ and the capacity of vessel 11′. Oscillations are sustained due to a second phase angle determined by inter alia subcircuit 13′ comprising dissipative processes 260, 262 and capacitive processes 261, 263 wherein each said dissipative process comprises any one, or combination of the following: viscous drag, thermal resistance or mechanical friction and each capacitive process comprises any one, or combination of the following: hydrostatic pressure change due to a flow, fluid compressibility, thermal capacitance, or elasticity; and wherein, the magnitude of the pressure changes in the working fluid increases or remains constant with time due to at least one mechanism giving rise to a gain.