Study On Design And Matching Of The Turbocharger For A Gasoline Engine472QZ

With the rapid growth of car ownership in the world, the energy saving and emission reduction for vehicles is becoming more and more urgent, since the petroleum resource’s shortage has caused rise of oil prices a lot. Turbo-supercharged engine make use of exhausted gas with a certain temperature and pressure to drive the turbine to work, so as to drive the compressor to rotate, thus compressing the air. In this way, energy of the exhausted gas is recovered. So the engine can not only obtain a satisfying fuel economy, but also can get a strong power. Once more, a better balance between power performance and environmental protection performance is also can be achieved, and the energy-saving is very obvious. So the turbocharger technology is an important developing direction for gasoline engine.Based on the review of domestic and foreign relevant literature, the background, purpose, method and significance of turbocharged gasoline engine were summarized in this dissertation. Then the gasoline engine472QZ (displacement1.5L) was treated as a original machine, whose turbocharger matching design was conducted, which was based on such a research or development idea that starting from the basic parameters of the machine, as well as combining theoretical calculation, empirical design and experimental matching. The main contents and conclusions of this dissertation are summarized as follows:(1) The matching principle between the various parts of the turbocharger, between the gasoline engine and the turbocharger were summarized, which can provide guidance for the design of the gasoline engine turbocharger.(2) Through analysing the relevant data of gasoline engine472QZ, the turbocharger compression ratio and it’s air flow were respectively determined at the design point. Accordingly, the thermal calculation for compressor impeller and turbine structure, so well as their size were carried out, then the compressor and turbocharger’s outer size was fixed. (3) With software NUMECA, the analysis about some key performance parameters of the turbine were conducted, such as it’s end tip clearance, the inlet absolute flow angle, the pressure of turbo tank outlet diffuser, and the structure of the exhaust pipe. These analysis results provide a reference for the design of the engine exhaust pipe.(4) Based on the test-bed in Hunan Tianyan Machinery Co. Ltd., the turbocharger JQ48compressor characteristic experiment was introduced, and the compressor characteristic curve of JQ48was drawn. Corporation with a engine laboratory, the united matching experiment between gasoline engine and turbocharger was also carried out. According to the experiment, the outer characteristic curve of joint operation between gasoline engine472QZ and turbocharger JQ48was obtained. The experimental results show that after the gasoline engine472QZ equipped with the turbocharger JQ48,it’s output torque increases by58.2%, the output power increases by58.5%, while it’s fuel consumption decreases by18.7%at the design point. That indicates the matching effect meets the design requirements. The results of this study demonstrate that turbo technology is very helpful for improving the power performance and the fuel economy. Meantime, the design method of gasoline turbocharger that combining theoretical calculation, optimal analysis and experiment is also presented, which has a certain high practical value.