Internal Flow Field Analysis And Structural Improvement Of NDIR Automobile Exhaust Sensor

With the constant progress of Chinese real economy,the car ownership is increasing year by year,and the environment pollution problem is also going from bad to worse.So it’s very important to do the automobile exhaust emission detection.The exhaust emission detection is achieved by the automobile exhaust sensor which uses non-dispersive infrared absorption method to measure the density of automobile exhaust simultaneously.When detecting the automobile exhaust,the turbulence of the sampling exhaust gas in the air chamber will make infrared bad absorbed by the hydrocarbon,carbon monoxide,carbon dioxide among the exhaust gas,which can influence the accuracy of the detection and the response time.Consequently it’s necessary to make research on the sensor structure and inner gas’ s flow behavior to improve the detection accuracy of the sensor and the response time.This paper takes the NDIR automobile exhaust sensor as the research object,elaborates the domestic and foreign NDIR automobile exhaust sensor research progress,and the method of the internal flow field.Then it introduces the principle of the detection system,including infrared absorption principle,selection of each component in the exhaust gas infrared spectroscopy and NDIR detection principle,and particularly introduces the basic theory of internal flow field analysis about NDIR automobile exhaust sensor,including the mathematical model of internal flow field and the grid generation technology.Finally,this paper respectively divides structured grid and non-structured grid for NDIR automobile exhaust sensor’s internal flow field by the ICEM CFD software.Use the Realizable k-ε turbulence model and SIMPLE algorithm to do the numerical simulation analysis on the automobile exhaust sensor’s internal flow field by Fluent with finite volume method.The paper also improves the automobile exhaust sensor structure and does both the numerical simulation analysis and the experiment verification.The experiment result shows that the improved automobile exhaust sensor has a shorter response time and a higher accuracy,which is less affected by the velocity of flow.