High Quality Delivery Valve 161S2 Diesel Engine Spare Parts

Abstract
The delivery valve is a crucial component in high-pressure fuel injection pumps, governing both fuel discharge and return flow during the injection cycle. Among its structural parameters, the seat cone angle plays a decisive role in determining the flow characteristics of returning fuel, which in turn affects residual pressure, cavitation risk, and injection stability. This study investigates the influence of different cone angle designs on return flow behavior using computational fluid dynamics (CFD) analysis and experimental validation.

1. Introduction
In modern diesel engines, precise fuel injection is critical to achieving high efficiency and low emissions. The delivery valve not only controls fuel delivery but also regulates the return flow after injection. Improper design of the valve seat cone angle may lead to unstable return flow, excessive cavitation, and high residual pressure, ultimately causing secondary injection or irregular combustion. Therefore, understanding the relationship between cone angle and return flow dynamics is essential for optimizing injector performance.

2. Methodology

• Geometric modeling: Several valve seat cone angles (ranging from 30° to 90°) were selected for investigation.

• CFD analysis: The fluid domain was simulated under ultra-high-pressure conditions, with parameters such as velocity field, pressure distribution, and cavitation intensity analyzed.

• Experimental setup: A high-pressure test rig with transparent sections was employed to visualize flow behavior and validate simulation results.

3. Results
Simulation results revealed clear trends:

• Smaller cone angles (30°–45°) created narrow return passages, leading to higher flow velocity and localized cavitation near the valve seat.

• Moderate cone angles (60°–70°) promoted smoother fuel return, reducing pressure fluctuation and minimizing cavitation risk.

• Larger cone angles (80°–90°) increased the flow area, but excessive backflow energy caused instability in pressure recovery and longer damping times.

Experimental data confirmed the simulation findings. Valves with 60°–70° cone angles exhibited the most stable return flow characteristics, with residual pressure reduced by approximately 15% compared to smaller cone angle designs. High-speed visualization showed that cavitation bubbles were significantly suppressed under the optimized geometry.

4. Discussion
The study demonstrates that the cone angle strongly influences return flow stability and cavitation behavior. While smaller angles enhance sealing, they intensify cavitation. Conversely, larger angles provide greater flow capacity but increase instability. An optimal cone angle range of 60°–70° achieves a balance between sealing, flow efficiency, and pressure stability. This insight provides practical guidance for injector designers seeking to minimize flow-induced losses and improve overall injection consistency.

5. Conclusion
The cone angle of the delivery valve seat has a direct and measurable effect on return flow characteristics. By selecting an optimal cone angle, return flow can be stabilized, cavitation minimized, and residual pressure effectively controlled. These improvements contribute to enhanced fuel injection accuracy, reduced secondary injection risk, and extended component durability.