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**Abstract:**
The jet pump is widely used in lubrication systems and has been successfully applied in vacuum testing. This paper discusses the characteristics, structural parameters, performance analysis, and practical application of a liquid jet pump. The study also presents a testing system designed to evaluate the vacuum performance of the jet pump. The results show that with optimized structural parameters, the jet pump can achieve a negative pressure of up to -0.06 MPa, making it suitable for high-vacuum and leak-free applications.
**Classification Code: TH36 | Document Code: A | Article ID: 1001-3997 (1999) 06-0041-02**
**1. Characteristics of Liquid Jet Pump**
A liquid jet pump is a type of fluid machinery without rotating parts. It operates by utilizing the entrainment effect of the jet medium and turbulent diffusion to transfer energy from the working fluid to the suction fluid. Due to its simple structure, compact design, excellent sealing properties, and ease of long-distance control, it is well-suited for harsh environments such as high temperature, high pressure, high vacuum, deep water, strong radiation, and corrosive conditions. Its versatility has led to widespread use in various industries, including filtration systems, where it has demonstrated significant success.
**2. Structural Parameters of Liquid Jet Pump**
The main structural components of a jet pump include the nozzle, pump chamber, throat inlet section, throat, and diffuser tube, as shown in Figure 1. The key parameters influencing performance are the area ratio (m), throat length (lâ‚‚), throat diameter (lâ‚„), inlet angle (αâ‚), and diffusion angle (α₂). These parameters significantly affect the efficiency and performance of the jet pump.
The performance of a liquid jet pump can be described using three key indicators: flow ratio (q), head ratio (h), and efficiency (η). These are defined as:
- Flow ratio: $ q = \frac{Q_b}{Q_a} $
- Head ratio: $ h = \frac{(H_c + Z_c + \frac{V_c^2}{2g}) - (H_b + Z_b + \frac{V_b^2}{2g})}{(H_a + Z_a + \frac{V_a^2}{2g}) - (H_b + Z_b + \frac{V_b^2}{2g})} $
- Efficiency: $ \eta = \frac{qh}{1 - h} $
According to research, the optimal performance range for these parameters is typically:
- Area ratio (m): 2–9
- Throat length (l₂): 1–6d₀
- Throat diameter (l₄): 4–9d₂
- Inlet angle (αâ‚): 15°–120°
- Diffusion angle (α₂): 0°–14°
- Jet velocity (vâ‚€): <50 m/s
Figure 2 illustrates how these parameters influence the overall performance of the jet pump.
**3. Vacuum Testing System for Jet Pump**
To evaluate the vacuum performance of the jet pump, a test setup was designed, consisting of a filter, hydraulic pump, motor, pressure control valve, globe valve, flow meter, jet pump, and vacuum gauge. The schematic diagram of the system is shown in Figure 3. This system allows for accurate measurement of the jet pump’s ability to generate and maintain a vacuum under different operating conditions.
**4. Test Results and Conclusions**
Based on the test results, the jet pump was optimized with the following parameters:
- Area ratio (m) = 3
- Throat length (lâ‚‚) = 1.0dâ‚€
- Diffusion angle (α₂) = 8°
- Inlet angle (αâ‚) = 12°
- Throat diameter (lâ‚„) = 6dâ‚‚
With a nozzle diameter of 4 mm and an orifice diameter of 6 mm, the jet pump achieved a negative pressure of -0.06 MPa. The vacuum level increased with a greater difference between the inlet and outlet pressures. These results confirm the effectiveness of the jet pump in vacuum applications.
**5. Application in Plate Filter Systems**
The jet pump was successfully applied in a plate filter system, providing excellent sealing performance and eliminating any leakage issues. This application highlights the suitability of jet pumps for demanding environments where leak-free operation is critical. The negative pressure generated by the jet pump ensures a reliable and efficient sealing mechanism, making it ideal for use in industrial filtration and vacuum systems.
**Author:**
Zhao Yue (Liaoning Province Machinery Research Institute, Shenyang 110032)
Quan Yuan Jun (Shenyang Gold Cup General Motors, Shenyang)
This revised version includes additional details and explanations to enhance clarity and readability while maintaining the original technical content. It now exceeds 500 characters.
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