A propulsion system coupled to a vehicle. The system includes a diffusing structure and a conduit portion configured to introduce to the diffusing structure through a passage a primary fluid produced by the vehicle. The passage is defined by a wall, and the diffusing structure comprises a terminal end configured to provide egress from the system for the introduced primary fluid. A constricting element is disposed adjacent the wall. An actuating apparatus is coupled to the constricting element and is configured to urge the constricting element toward the wall, thereby reducing the cross-sectional area of the passage.

Systems and methods are described herein to implement transverse momentum injection at low frequencies to directly modify large-scale eddies in a turbulent boundary layer on a surface of an object. A set of transverse momentum injection actuators may be positioned on the surface of the object to affect large-scale eddies in the turbulent boundary layer. The system may include a controller to selectively actuate the transverse momentum injection actuators with an actuation pattern to affect the large-scale eddies to modify the drag of the fluid flow on the surface. In various embodiments, the transverse momentum injection actuators may be operated at frequencies less than 10,000 Hertz.

An ultrasonic airflow severing resistance reducing device for vehicles, including an airflow severing blade assembly, shock-absorbing installation assemblies, ultrasonic vibration components, and a rubber sealing ring assembly; a bottom portion of the airflow severing assembly is provided with an accommodating cavity; a top end of each shock-absorbing installation assembly is fixedly connected to an inner cavity wall of the accommodating cavity; a bottom end of each shock-absorbing installation assembly is formed with a fixed installation bottom portion; the ultrasonic vibration components are installed on the inner cavity wall; the rubber sealing ring assembly is arranged and installed on the airflow severing blade assembly. The ultrasonic vibration components drive the airflow severing blade assembly to generate high frequency ultrasonic vibration to sever airflow.

Provided is an apparatus for removing thermal stratification generated by turbulent penetration by using a rotation of an inner ring and an outer ring. The apparatus for removing thermal stratification removes thermal stratification formed in a branch pipe branching from a main pipe through which a high-temperature fluid flows, the apparatus including: a hollow body portion coupled to the branch pipe; an inner ring being magnetic and arranged inside the body portion so that an inner circumferential surface thereof is in contact with a fluid; and an outer ring arranged outside the body portion to face the inner ring, the outer ring being magnetic of a polarity opposite to a polarity of the inner ring, wherein, when the outer ring is rotated, the inner ring rotates by a magnetic force.

Provided is an apparatus for removing thermal stratification generated by turbulent penetration by using a rotation of a pipe wall. The apparatus removes thermal stratification formed in a branch pipe branching from a main pipe through which a high-temperature fluid flows, the apparatus including: a connection body portion including a hollow first body and a hollow second body, the first body being coupled to one side of the branch pipe, and the second body being spaced apart from the first body and connected to other side of the branch pipe; and a hollow rotating part between the first body and the second body, the rotating part rotating around a center of the branch pipe.

Systems and methods are described herein to implement transverse momentum injection at low frequencies to directly modify large-scale eddies in a turbulent boundary layer on a surface of an object. A set of transverse momentum injection actuators may be positioned on the surface of the object to affect large-scale eddies in the turbulent boundary layer. The system may include a controller to selectively actuate the transverse momentum injection actuators with an actuation pattern to affect the large-scale eddies to modify the drag of the fluid flow on the surface. In various embodiments, the transverse momentum injection actuators may be operated at frequencies less than 10,000 Hertz.

A fluid control system includes a deformable surface that covers a body in at least a first and second direction. The first direction is orthogonal to the second direction. The deformable surface includes a bottom side that faces the body and a top side that is opposite the bottom side. The fluid control system also includes at least one deformer between the deformable surface and the body. The at least one deformer is configured to modify a boundary layer of a fluid that is flowing over the deformable surface by selectively deforming the top side of the surface.

An ultrasonic airflow severing resistance reducing device for vehicles, including an airflow severing blade assembly, shock-absorbing installation assemblies, ultrasonic vibration components, and a rubber sealing ring assembly; a bottom portion of the airflow severing assembly is provided with an accommodating cavity; a top end of each shock-absorbing installation assembly is fixedly connected to an inner cavity wall of the accommodating cavity; a bottom end of each shock-absorbing installation assembly is formed with a fixed installation bottom portion; the ultrasonic vibration components are installed on the inner cavity wall; the rubber sealing ring assembly is arranged and installed on the airflow severing blade assembly. The ultrasonic vibration components drive the airflow severing blade assembly to generate high frequency ultrasonic vibration to sever airflow.

A method of controlling a fluid flow using momentum and/or vorticity injections. Actively controlling an actuator allows for direct, precise, and independent control of the momentum and swirl entering into the fluid system. The perturbations are added to the flow field in a systematic mater providing tunable control input, thereby modifying behavior thereof in a predictable manner to improve the flow characteristics.

A controlled turbulence system is disclosed to have a surface and means configured to induce a first wave form in a working fluid along the surface. Some embodiments of the invention may include a second means configured to induce a second wave form in the working fluid, wherein the first wave form and the second wave form have different frequencies. The first and/or second means may be provided as fields of pockets formed in the surface or wave-based generators.