Abstract A high-pressure natural gas direct injection engine can achieve lean combustion and diffusion combustion of natural gas, which can reduce the emission level and improve power performance. However, the transient gas injection rate of the injector directly affects the combustion rate. In order to optimize engine performance, it is essential to focus on the technology used to measure the transient injection rate. Therefore, in this study, a method is developed to measure the transient flow rate of a high-pressure natural gas pulse injector. First, experiments were conducted to locate the optimum position for sensor installation, thereby ensuring the quality of the signal. Subsequently, a mass flow meter and schlieren imaging method was used to verify the injection mass and injection start/end timing. Finally, the common working conditions of a certain type of injector are measured. Results indicated that the test error of the cycle injection mass and injection start/end timing did not exceed 4% and 2.1%, respectively. As the injector energizing time increased, the injection rate curve changed from triangle to trapezoid. As the injection pressure increased, the injection start delay time decreased and end delay time increased. Measurement of the main and post injection strategy indicates that the main injection has a significant impact on the injection mass and injection rate curve for post injection. When the interval between the two injections is short, the injection rate curves merge. This increases the injection duration. The total injection mass of the main injection and post injection mass is found to be significantly higher than the sum of the two independent injections.

中文翻译：

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高压天然气脉冲喷射器瞬态喷射流量的测量与验证

摘要 高压天然气直喷发动机可实现天然气的稀薄燃烧和扩散燃烧，降低排放水平，提高动力性能。然而，喷射器的瞬态气体喷射率直接影响燃烧率。为了优化发动机性能，必须关注用于测量瞬态喷射率的技术。因此，在本研究中，开发了一种测量高压天然气脉冲喷射器瞬态流量的方法。首先，通过实验确定传感器安装的最佳位置，从而保证信号质量。随后，使用质量流量计和纹影成像方法来验证注入质量和注入开始/结束时间。最后，测量某类喷油器的常见工况。结果表明，循环喷射质量和喷射开始/结束时间的测试误差分别不超过4%和2.1%。随着喷油器通电时间的增加，喷油量曲线由三角形变为梯形。随着注射压力的增加，注射开始延迟时间减少，结束延迟时间增加。主、后喷射策略的测量表明，主喷射对后喷射的喷射质量和喷射速率曲线有显着影响。当两次注入之间的间隔较短时，注入速率曲线合并。这增加了注射持续时间。