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A vacuum ejector, or simply ejector, or aspirator, is a type of vacuum pump, which produces vacuum by means of the Venturi effect.. In an ejector, a working fluid (liquid or gaseous) flows through a jet nozzle into a tube that first narrows and then expands in cross-sectional area.
Figure 1: A de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow Density flow in a nozzle. A rocket engine nozzle is a propelling nozzle (usually of the de Laval type) used in a rocket engine to expand and accelerate combustion products to high supersonic velocities.
A de Laval nozzle (or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube which is pinched in the middle, with a rapid convergence and gradual divergence. It is used to accelerate a compressible fluid to supersonic speeds in the axial (thrust) direction, by converting the thermal energy of the flow into kinetic energy .
The simplest apparatus is a tubular setup known as a Venturi tube or simply a Venturi (plural: "Venturis" or occasionally "Venturies"). Fluid flows through a length of pipe of varying diameter. To avoid undue aerodynamic drag, a Venturi tube typically has an entry cone of 30 degrees and an exit cone of 5 degrees. [1]
An injector is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is entrained in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic pump with no moving parts except a valve to control inlet flow.
The high-pressure spray nozzle (up to 689 kPa or 100 psig) is aimed at the throat section of a venturi constriction. The ejector venturi is unique among available scrubbing systems since it can move the process gas without the aid of a fan or blower. The liquid spray coming from the nozzle creates a partial vacuum in the side duct of the scrubber.
Therefore, spray towers use nozzles that produce droplets that are usually 500–1000 μm in diameter. Although small in size, these droplets are large compared to those created in venturi scrubbers that are 10–50 μm in size. The gas velocity is kept low, from 0.3 to 1.2 m/s (1–4 ft/s), to prevent excess droplets from being carried out of ...
The velocity of the air flow entering the carburetor is measured by placing one or more venturi directly in the airflow. The venturi creates a low pressure that changes with the velocity of the air. As the air pressure in chamber A is decreased with greater airflow, the diaphragm is pulled toward the carburetor body.