双燃料喷射器油-气瞬时质量流率同场测量方法

Simultaneous Measurement of Instantaneous InjectionRate of a Dual Fuel Injector

提出一种组合式的测量方法,将其应用于缸内高压直喷柴油/天然气发动机双燃料喷射器瞬态燃料质量流率的研究,实现了两相燃料同场高精度测试.针对传统“动量法”只能获取喷气规律型线无法获取准确质量流率的问题,提出一种平行测试的方法,通过采集测试容腔内的压力变化获取循环喷气量,结合瞬态动量信号得到精确的喷气规律曲线.并对喷射器的计量特征及时间特征进行验证.最后对柴油/天然气双燃料喷射器常用工况进行测试,结果表明:该方法解决了两相燃料难以同场测量的问题,实现了双燃料喷射器油-气瞬时质量流率的精确测量;喷气量测试误差不超过5%,喷油及喷气起始时刻与结束时刻的测试误差不超过0.113 ms,喷油量及喷气量的波动率分别不超过1.4%和2.9%.随着燃料喷射压力增加,喷射器的开启时段减小、关闭时段增加,且内部轴针开启和关闭的速度均大于外部轴针.引燃油的喷射通过影响喷气持续期影响喷气量,先油后气喷射方式下的喷气量在仅喷气方式下的喷气量上、下波动.

A combined measurement method was proposed and applied to the study of transient dual fuel injection rate of a high-pressure nature gas and diesel co-direct injection engine.Firstly,since the traditional"momentum method"could only obtain the injection pattern but not the accurate injection rate,a parallel test method was proposed to obtain the circular injection quantity by collecting and testing the pressure change in the cavity,and the accurate gas injection pattern curve by combining the transient momentum signal.Then,the measurement and time characteristics of the injector were verified.Finally,the common working conditions of the diesel-natural gas dual fuel injector were tested.The results show that the method solves the problem that two-phase fuel injection rates are difficult to measure in the same field,and achieves the accurate measurement of the instantaneous injection rate of diesel and natural gas in the dual fuel injector.The test error of injection mass is not more than 5%,and the test error at the start moment and end moment of injection is not more than 0.113 ms.Besides,the fluctuation rate of diesel injection mass and natural gas injection mass is not more than 1.4%and 2.9%,respectively.With the increase of injection pressure,the opening period of the injector decreases and the closing period increases,and the opening and the closing speeds of the internal diesel needle are greater than those of the external gas needle.The injection of diesel injection affects the gas injection mass by affecting the duration of the gas injection,and the gas injection mass fluctuates up and down with the gas-only injection.