Abstract: A fluid power-extraction machine is immersed in an ambient flow of a fluid, captures (and extracts energy from) a portion of the fluid, and discharges it back into the ambient flow. The machine includes a housing bounding a fluid intake inlet and including an ambient flow deflector, a downstream body arranged rearwardly from the deflector and forming a discharge outlet between the deflector and the downstream body, and a power extraction device in a fluid flow channel communicating from the fluid intake inlet to the discharge outlet. The deflector outwardly deflects and accelerates a portion of the ambient flow adjacent to the discharge outlet. A mixing surface of the downstream body extends outwardly and rearwardly from the discharge outlet, mixing the accelerated flow, the discharged flow and the ambient flow together along the mixing surface. A backflow preventer of the downstream body prevents wake backflow from impeding discharge of spent flow at the discharge outlet.

Abstract: A fluid power-extraction machine is immersed in an ambient flow of a fluid, captures (and extracts energy from) a portion of the fluid, and discharges it back into the ambient flow. The machine includes a housing bounding a fluid intake inlet and including an ambient flow deflector, a downstream body arranged rearwardly from the deflector and forming a discharge outlet between the deflector and the downstream body, and a power extraction device in a fluid flow channel communicating from the fluid intake inlet to the discharge outlet. The deflector outwardly deflects and accelerates a portion of the ambient flow adjacent to the discharge outlet. A mixing surface of the downstream body extends outwardly and rearwardly from the discharge outlet, mixing the accelerated flow, the discharged flow and the ambient flow together along the mixing surface. A backflow preventer of the downstream body prevents wake backflow from impeding discharge of spent flow at the discharge outlet.

Abstract: A turbine apparatus is immersed in an ambient stream of a flowing fluid, such as water, so as to encapture a portion of the flowing fluid and extract power therefrom, before returning it back into the ambient stream, which may be a tidal flow of ocean water, or a relative flow of water behind a boat. The apparatus includes a converging intake duct with an inlet opening that faces forward into the ambient stream flow, a spiral volute casing that redirects the fluid into a spiral flow, a rotor arranged coaxially on the spiral axis, and an exhaust duct that diverges and curves from an exhaust inlet coaxial with the spiral axis to an exhaust outlet that opens rearwardly into the ambient flow. The rotor has a peripheral rotor inlet around the circumference of a first stage thereof and an axial rotor outlet at one axial end thereof, and is arranged with its rotor axis coinciding with the spiral axis oriented transverse to the ambient stream flow.

Abstract: A turbine apparatus is immersed in an ambient stream of a flowing fluid, such as water, so as to encapture a portion of the flowing fluid and extract power therefrom, before returning it back into the ambient stream, which may be a tidal flow of ocean water, or a relative flow of water behind a boat. The apparatus includes a converging intake duct with an inlet opening that faces forward into the ambient stream flow, a spiral volute casing that redirects the fluid into a spiral flow, a rotor arranged coaxially on the spiral axis, and an exhaust duct that diverges and curves from an exhaust inlet coaxial with the spiral axis to an exhaust outlet that opens rearwardly into the ambient flow. The rotor has a peripheral rotor inlet around the circumference of a first stage thereof and an axial rotor outlet at one axial end thereof, and is arranged with its rotor axis coinciding with the spiral axis oriented transverse to the ambient stream flow.