A fluid mover comprising: a hollow body provided with a straight-through passage with an inlet at one end of the passage and an outlet at the other end of the passage for the entry and discharge respectively of a working fluid; a nozzle substantially circumscribing and opening into said passage intermediate the inlet and outlet ends thereof; an inlet communicating with the nozzle for the introduction of a transport fluid; and a mixing chamber being formed within the passage downstream of the nozzle; wherein the nozzle is an annular nozzle which has a convergent-divergent geometry internally thereof, and the passage is of substantially constant cross section, which optimise the energy transfer between the transport fluid and working fluid such that in use through the introduction of transport fluid the working fluid is atomised to form a dispersed vapour/droplet flow regime with locally supersonic flow conditions within a pseudo-vena contracta, resulting in the creation of a supersonic condensation shock wave within the downstream mixing chamber by the condensation of the transport fluid; characterised in that the fluid mover further comprises: a controllable transport fluid source in fluid communication with the transport fluid inlet, wherein the transport fluid source is adapted to control the pressure of the transport fluid at the inlet such that a momentum flux ratio between the transport fluid and working fluid lies in the range 2 ≤ M ≤ 70; and a microprocessor coupled to the transport fluid source and to at least one sensor that monitors one or more properties of the mixed fluids within the downstream mixing chamber which relate to the resulting supersonic condensation shock wave, the microprocessor being adapted to allow the transport fluid source to control the pressure of the transport fluid based on information measured through said at least one sensor. a hollow body provided with a straight-through passage with an inlet at one end of the passage and an outlet at the other end of the passage for the entry and discharge respectively of a working fluid; a nozzle substantially circumscribing and opening into said passage intermediate the inlet and outlet ends thereof; an inlet communicating with the nozzle for the introduction of a transport fluid; and a mixing chamber being formed within the passage downstream of the nozzle; wherein the nozzle is an annular nozzle which has a convergent-divergent geometry internally thereof, and the passage is of substantially constant cross section, which optimise the energy transfer between the transport fluid and working fluid such that in use through the introduction of transport fluid the working fluid is atomised to form a dispersed vapour/droplet flow regime with locally supersonic flow conditions within a pseudo-vena contracta, resulting in the creation of a supersonic condensation shock wave within the downstream mixing chamber by the condensation of the transport fluid; a controllable transport fluid source in fluid communication with the transport fluid inlet, wherein the transport fluid source is adapted to control the pressure of the transport fluid at the inlet such that a momentum flux ratio between the transport fluid and working fluid lies in the range 2 ≤ M ≤ 70; and a microprocessor coupled to the transport fluid source and to at least one sensor that monitors one or more properties of the mixed fluids within the downstream mixing chamber which relate to the resulting supersonic condensation shock wave, the microprocessor being adapted to allow the transport fluid source to control the pressure of the transport fluid based on information measured through said at least one sensor.