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Spark energy is one of the most important parameters for SI engine, so it need be controlled effectively. Two modes of spark energy measurement were introduced in this paper: simulation load and direction measurement. 4 kinds of simulation load can be found: spherical discharger, three-pole discharger, Zener discharger and Zener string discharger, each has its own character. Zener string was chosen for it suited to electronic-controlled automotive engine. 2 kinds of direction measurement were introduced: attemperator, voltage and current sensor, the later was adopted for it can be realized easily and its precision characteristic. The test results show that the spark energy can be measured quantitatively and effectively in both modes; and the calculated spark energy of simulation load is larger than direction measurement for its less loss at the ignition circuit.

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Hydrogen-air flame stability with different initial pressures is studied in a constant volume combustion cell. The schlieren flame images and the pressure curves are obtained under various initial pressures, equivalence ratios and initial temperatures. The results show that the time of the laminar flame stage is decreasing with the increasing initial pressure. The main reason of the rapid increasing pressure is whether the squish flame appears. The squish flame stage does not occur when the value of the initial pressure is very low. At this time, the varibility of the pressure is very low. The pressure oscillation occurs when the squish flame or the main flame transmits to the under wall surface. Meanwhile, under the different initial conditions, the time of the mixture combustion process stages is often different, and the flame stability is different. At the same time, the flame crtical radius is decreasing when the initial pressure is increasing.