Modeling of Air-powered Engine Based on Time Coordinate and Optimal Approachof Gas Distribution Parameters

摘要

The objective of this research is to provide systematic investigations to modeling and optimal design of the air-powered engine for improving its comprehensive performance. A thermo-dynamics model of the air-powered engine based on time coordinate is established. The simulation and analysis results show that the gas distribution parameters are the key factors to get a valid performance for the air-powered engine, such as a large valve overlap angle leading to a low efficiency of the air-powered engine in particular. A performance evaluating function of the air-powered engine considering power output and energy conversion efficiency is proposed. To improve the searching efficiency in optimization, four gas distribution parameters associated with the comprehensive performance of the air-powered engine including the intake advance angle, basal of intake sustain angle, exhaust advance angle and exhaust delay angle, are divided as a mainstream factor group and a subordinate factor group according to their relative importance. So the iterative search in optimization becomes more efficient. An example is illustrated to show the validity of the modeling. The optimal simulation result shows that we can get a bigger power output with 19.7% more than the original state and bigger energy conversion efficiency with 98.47% more than originalrnstate.