Abstract
Ensuring the long-term durability of injector nozzles is essential for maintaining stable fuel injection performance and achieving high engine reliability throughout the vehicle’s service life. However, real-time durability evaluation requires extremely long test periods and high operating costs. To address this problem, this study proposes an accelerated aging experimental method specifically designed for injector nozzle durability testing. By amplifying key degradation factors—such as high-frequency cyclic loading, thermal shock, fuel contamination, and cavitation erosion—the method enables rapid simulation of long-term wear, sealing degradation, and flow loss that would occur during years of engine operation. The results demonstrate that the accelerated aging approach effectively shortens durability evaluation time while preserving high correlation with real-vehicle aging mechanisms.
1. Introduction
Injector nozzles operate under harsh conditions including high pressure, high temperature, rapid switching frequency, and chemically complex fuels. Over time, phenomena such as orifice erosion, needle sticking, carbon deposits, and sealing wear can significantly alter spray characteristics. Traditional durability tests often require thousands of hours, which is impractical for rapid product development. Therefore, an accelerated method that can reproduce real aging behaviors in shorter time is urgently needed.
2. Accelerated Aging Mechanism and Design Principles
The proposed method is based on the principle of damage equivalence. By intensifying degradation factors, the cumulative damage produced in a shorter test period matches that of long-term field use. Key acceleration mechanisms include:
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High-pressure cycling: increasing injection frequency to magnify fatigue and impact wear.
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Thermal cycling: alternating −30°C to 150°C to replicate thermal expansion stress.
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Contaminated fuel simulation: adding abrasive micro-particles to accelerate erosion.
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Cavitation intensification: raising pressure drop to stimulate bubble collapse damage.
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Chemical aging: using fuel formulations with enhanced oxidative and corrosive effects.
3. Experimental Setup and Procedure
A customized test bench is developed consisting of a high-pressure pump, controllable injector driver, thermal chamber, contaminant dosing unit, and online flow monitoring system. The test procedure includes:
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Baseline characterization: flow rate, spray angle, SMD, sealing leakage.
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Accelerated aging cycle: repeating combined mechanical, thermal, and chemical stress tests.
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Periodic measurements: real-time tracking of flow decay and sealing performance.
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Post-test analysis: micro-surface wear examination using SEM and profilometry.
4. Results and Discussion
The accelerated method achieved equivalent damage of approximately 1,000 hours of field usage within only 120 hours of testing. Flow loss, needle motion delay, and erosion patterns closely matched real-engine endurance results, confirming the validity and reliability of the acceleration model.
5. Conclusion
This study provides a scientifically grounded and highly efficient accelerated aging methodology for injector nozzle durability testing. It can significantly reduce product development cycles, support rapid design iteration, and enhance reliability evaluation capabilities for modern fuel injection systems.
