| Marine gas engine is the new green power generation; in recent years it developed quickly as a result of its outstanding better economy and emission characteristics compared to traditional diesel engine. To improve break mean effective pressure, reduce NOx emission amount and avoid knocking, lean burn strategy is adopted by marine gas engine. The key to guarantee effective lean burn circumstance is to increase ignition energy. It is an effective method to increase ignition energy by utilizing prechamber enrichment injection strategy which improves turbulence, assures reliable ignition and forms flame source. Therefore, achieving high-quality prechamber mixture enrichment is fundamental to lean burn strategy. To master flow field variation regulation and then understand mixture quality control pattern in the enrichment injection process, the paper dealt with the prechamber enrichment injection process in a large marine gas engine.The paper summarized velocity field measurement methods, then brought out PIV method, designed the whole experimental system and scheme to measure the enrichment injection flow field. Then testified the experiment results combining similitude principle and numerical simulation result of the flow field in the prechamber. The qualitative analysis of the result revealed that center jet has large penetration in the prechamber with tumble formed, and flow field assumes to have important effect on fuel distribution.Finally, the paper provided flow fields of5°,9°, and11°enrichment injection inlet angles in the prechamber by PIV experiment, to test the influence of different inlet angles. Both the flow fields of5°and9°inlet angles showed no obvious difference to the one of7°inlet angle in geometry. When the flow field is of11°, tumble created on both sides of the center jet, which showed different tendency of7°, and the turbulence increased inside the prechamber. The results offered optimization suggestions of enrichment injection inlet angles. |
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