空气动力发动机气缸容积及程径比的研究

Research on displacement and stroke-bore ratio of air-powered engine

气缸容积和程径比是进行气动发动机设计的关键参数.在通过热力学和动力学分析对气动发动机工作过程建立并经试验验证的数学模型的基础上,运用仿真方法研究探讨了不同气缸容积与程径比的组合对发动机工作特性的影响情况,提出了相关选用准则,为优化气动发动机设计,提高气动发动机性能打下良好的基础.

Displacement and stroke-bore ratio are two basic parameters in designing an Air-powered Engine （APE）. To analyze the effects of them on the performance of APE, the model of APE was built up based on the thermodynamic analysis. And a prototype APE converted from a single-cylinder four-stroke gasoline engine was tested for checking the accuracy of the model. Good agreement of computation results is obtained between the results calculated from the model and the experiment data of the prototype engine. Based on the model, simulation was carried out with different combinations of displacements and stroke-bore ratios to study the influence of them on the engine performance. Results of simulation indicate that large displacement can raise the mean torque almost proportionally and boost the efficiency of APE while large stroke-bore ratio is of some benefit to increase the efficiency but has less effect on the torque. It can be adopted as the rule in APE design that displacement and stroke-bore ratio should be set as large as they can be to obtain a nice performance after weight and structure of the engine are considered comprehensively.