Visualization Research On Gas Injection Characteristics Of Engine Based On PLIF

With the requirement of energy conservation and emissions reduction is more and more high,we must go deeper into the gas injection,mixing and burning process of gas engine.So,laser diagnostics technology mainly includes planar laser induced fluorescence method,schlieren and shadowgraph.The jet of gas and its mixing with air are considered the most important processes.The jet characteristic of gas is one of the key factors to be considered when we design the engine,the jet development process has a direct impact on the efficiency of an engine,And it is also important to improve the engine’s emission performance.The gas jet and air mix to form air entrainment after the gas jet flowing out of the nozzle.The combustion process in engine cylinder is very dependent on the mixture distribution of fuel and air,and the distribution characteristics are directly related to the jet characteristic parameters.The quantitative measurement of gas jet concentration field is helpful to deeply understand the gas injection process,and it will laid the foundation for the further study of the dual fuel engine combustion process and numerical simulation work.This experiment is based on planar laser induced fluorescence PLIF technique,which is a non-intrusive,fast-response diagnostic technique with a high spatial and temporal resolution.It has been widely used in measurement of various complex flow fields.We choose acetone as the fluorescence tracer molecules and it was excited by laser sheet of 266 nm in the experiments.Fluorescence images were recorded by the intensified CCD camera.The gas jet concentration field of different working conditions is measured in two dimensions.Conducted a series of research on characteristics of gas jet at the same time,including the development process of gas jet and jet characteristics in different injection pressure and different nozzle size and different gas temperature.Then we obtain the development law of natural gas jet under different injection conditions.Quantitatively study the characteristic parameters of natural gas jet in different conditions by using laser induced fluorescence technology.The results show that as the increase of injection pressure,there is an increasing trend in the penetration and cone angle of the jet.The concentration of gas export will increase,and the distance concentration will not change much.With the increase of the diameter of the nozzle,the penetration and cone angle will also increase,the gas injection quality will increase,and the gas concentration will increase.The increase of gas temperature will decrease the quality of gas injection and the gas concentration will decrease under the same conditions.Therefore,in the condition of high temperature injection,injection pressure needs to be increased to improve jet quality.