Abstract: To optimize the design of air-powered engine and enhance its performance, an extensive experimental study on engine performance of a two-stroke air-powered engine that is modified from R175 diesel engine is carried out. Two evaluat- ing indicators are newly defined to evaluate the performance of the air-powered engine, namely specific mass flow and total energy efficiency. The lubricating experiment is carried out, three different lubricating oils, I.e. transformer oil, refrigerating oil and special oil are used. The experimental results show that the lubricating oil significantly influences the performance of the air-powered engine. When the water jacket is no water, or filled with room temperature water and hot water, the air-powered engine performance is studied. The experimental results show that the effect of heat exchange on engine per-formance is small and the multi-utilization of compressed air is helpful to enhance the total energy efficiency. To investigate the influence of valve timing on air-powered engine performance, three different inlet camshafts are used. The results of load characteristics and speed characteristics show that optimal per-formance is obtained when the inlet valve opening timing is 10 oCA before TDC. Under the condition of low engine speeds, the power performance and economy characteristic of air-powered engine are better.

Key words: Air-powered engine, Experimental study, Specific mass flow, Total energy efficiency