The Optimal Design Of Mixer Of CNG Engine

The environmental pollution and energy crisis have been promoting the development of substitute fuel of automobile. NG is a clean and ideal substitute fuel at present. This article analyzed the developmental level and situation of NGV in China and Overseas,and expounded the main contents of this article researched. The schemes of engine mapping and determining plan of the resistant coefficients of parts of areas were designed.The engine mapping data,vacuum degree and a lot of other data can be gained by engine mapping. This article used these data to analyze the factors that impact on dynamic performance of engine deeply,then drawn a conclusion that the throat area and the shrinking degree of the mixer are the main parameters. This article researched the relationship of the highest power of and the mixture density of NG and air meantime. These conclusions have been made as an important basis to design mixers optimally.This article also analyzed the flowing regulation of air and NG. The energy equation of Bernoulli can be gotten by the knowledge of hydrokinetics. Then mathematical relationship between the flows of mixture and the throat area,shrinking degree of mixer (mathematical model) can be established to meet the aim of the highest power of engine.This article used the 'constr' function of optimization toolbox of Matlab as a tool to optimize the mathematical model according to those data gotten by engine mapping and the installation condition of mixer,then,the initial optimal conclusion can be gotten. Analyzed the count error,and corrected the mathematical model,then the final optimal conclusion can be gained by optimizing the corrected mathematical model.The engine mapping tested and verified the design demand. Based on the above work,the power lose of using NG have been dropped to the lowest. By enhancing compression ratio of CNG engine and adding the enclose control system mating CNG engine,the dynamic performance decrease and bad emission of the refitted CNG engine can be resolved. Using these ways can make NGV become available and clean automobile really.