How an Ejector Works

Core Principle: The Venturi Effect

The ejector operates on the Venturi Effect. The core principle is that when a fluid passes through a converging cross-section, its velocity increases and its pressure decreases, thereby creating a negative pressure (vacuum) in a specific region that enables the suction of an external medium.

Operating Process

Step 1: Motive Fluid Entry and Acceleration

Pressurized motive fluid (typically water or another liquid) enters the injection chamber through the inlet. As it passes through the converging nozzle, the flow area is sharply reduced, causing the fluid velocity to increase dramatically and forming a high-speed jet.

Step 2: Throat Vacuum Formation and Medium Suction

As the velocity increases sharply, the pressure in the throat region of the ejector drops significantly. When the pressure falls below that of the gas or liquid connected to the suction port, a negative pressure (vacuum) is formed. Driven by this negative pressure, the gas (such as air, oxygen, or ozone) or liquid connected to the suction port is continuously drawn into the throat.

Step 3: Shearing, Dispersion, and Mixing

The entrained medium and the high-speed motive fluid meet inside the ejector, where they undergo intense shearing, dispersion, and turbulent mixing in the throat and mixing section. This process breaks the gas phase into fine bubbles and thoroughly disperses liquid droplets, achieving highly efficient two-phase mass transfer and mixing.

Step 4: Diffusion and Pressure Recovery

The mixed fluid then enters the gradually expanding diffuser section, where the flow area progressively increases and the velocity gradually decreases. According to Bernoulli's principle, a portion of the kinetic energy is converted into pressure energy, providing the mixed fluid with sufficient discharge pressure at the outlet for delivery to pipelines, tanks, or downstream treatment equipment.

Key Insight

A jet ejector itself does not generate power — it is an energy conversion and transfer device that must rely on a water pump or other external power source to provide sufficient flow and pressure to operate. As long as the pressure differential between the inlet and outlet meets the design requirements (typically no less than 25%–30%), the ejector can produce stable negative pressure at the throat and continuously draw in gas or liquid media.

Typical Applications

Based on the operating principle described above, ejectors can be widely applied in the following scenarios:

• Gas–Liquid Mixing: Drawing in air, oxygen, or ozone to achieve aeration and oxygenation, as well as ozone-based advanced oxidation
• Liquid–Liquid Mixing: In-line blending of two liquids, chemical dosing, and dilution
• Gas–Liquid Mass Transfer: High-efficiency oxygen transfer in wastewater treatment for aerobic biochemical processes
• Vacuum Suction: Operating as a liquid jet vacuum pump to extract gases or liquids
• Solid/Liquid Conveying: Using jet-induced negative pressure to suction and convey sludge, sediment, and slurries

Contact Information

Company Website: https://www.cd-greenwater.com
Technical Contact Number: 028-85130135
Customer Service Contact Number: 18515915124
Contact Email: jane1984@cd-greenwater.com
Address: No. 191, Section 1, Changcheng Road, Xihanggang, Shuangliu District, Chengdu