Analysis of cycle-to-cycle variation and non-uniformity of energy production: Tests on individual cylinders of a radial piston engine

Abstract

The paper presents results of identification tests on radial piston engine non-uniformity and non-repeatability of energy production. The tests are a part of the ASz-62IR engine modernization project aimed at extending the engine’s service life and decreasing fuel consumption. This is to be achieved by substituting a carburetor with an electronic injection control system. The tests consisted in measurements of in-cylinder pressure in each cylinder and were conducted under differing operating conditions. The paper focuses on the analysis of the indicated mean effective pressure (IMEP) as a parameter describing the amount of energy produced by the cylinders. IMEP mean values indicate significant differences in the amount of energy produced by individual cylinders. A further difference can be observed in the cycle-to-cycle variation of individual cylinders; it consists not only in the non-uniform standard deviation of IMEP, but also in the non-uniformity of IMEP, represented by the forgetting factor. The range of cylinder-to-cylinder variations has been evaluated and attributed to the non-uniform supply with the air-fuel mixture – a result of using a carburetor and an ignition system with fixed settings. ► I test the biggest, still produced radial piston engine for non-uniformity and non-repeatability of energy production. ► I measure indicated mean effective pressure simultaneously in each cylinder. ► I find differences in the cycle-to-cycle variation of individual cylinders energy production. ► The differences are in the non-uniform standard deviation of IMEP, and in the non-uniformity of IMEP. ► I conclude that the differences come from the non-uniform supply of cylinders with the air-fuel mixture.