A liquid ring pump includes a stationary housing that defines an inner space, and a drive shaft rotatably mounted within the stationary housing. The drive shaft defines a rotational axis. An impeller includes a plurality of blades extending radially outward with respect to the rotational axis, and each blade includes a root and a tip, wherein a continuous curve extends from the tip of each blade through the root of the blade and intersects with the rotational axis.

The present disclosure is directed to vortex generators for wind turbine rotor blades having noise-reducing features. For example, the vortex generators are mounted within a laminar flow region on either the pressure side or the suction side of the rotor blade and have a base portion with at least one airflow modifying element extending therefrom. The base portion has a leading edge and a trailing edge extending in a first direction. Further, the base portion includes one or more edge features formed within either or both of the leading or trailing edges. Moreover, the edge features are non-parallel with respect to the first direction so as to reduce laminar boundary layer instability noise.

A rotor blade for a wind turbine is provided, wherein the rotor blade includes serrations along at least a portion of the trailing edge section of the rotor blade. The serrations include a first tooth and at least a second tooth, and the first tooth is spaced apart from the second tooth. The area between the first tooth and the second tooth is at least partially filled with porous material such that generation of noise in the trailing edge section of the rotor blade is reduced. Furthermore, the embodiments relate to a wind turbine including at least one such a rotor blade.

A free floating wave energy converter includes at least one flexible pipe, adapted to float at a surface of a body of water, having an inlet end for receiving alternating slugs of water and air when the pipe is moored facing at an angle to a wave direction in the body of water and having an outlet end in fluid communication with a power takeoff and other devices, a plurality of supports attached to the pipe at spaced apart locations, each of the supports extending traverse to a longitudinal axis of the pipe and outwardly in opposite directions and at least two inflatable tubes attached to the supports on opposite sides of the pipe extending longitudinally substantially parallel to the longitudinal axis of the pipe, wherein the pipe is raised and lowered relative to the surface of the water by respectively inflating and deflating the tubes with a gas.

The invention is a wind turbine that is part of a system for utilizing the energy of wind to produce electrical energy. The turbine is a vertical axis wind turbine that is characterized by the design of its blades. The blades are shaped and attached to the turbine in a way that allows them to self-adjust their orientation with respect to the direction in which the wind is blowing. In this way the torque that each blade exerts on the turbine consist of two portions. When the blade is on the windward side of the turbine, it exerts on the turbine torque from the drag force. When the blade is on the leeward side of the turbine, the torque that the blade exerts on the turbine is from lift force.