| Spray impingement on wall as an avoidless phenomenon in middle and small cylinder bore diesels will cause accumulation of fuel on the wall of the combustion chamber, which results in high brake specific fuel consumption and HC & CO emissions. But it also can be used rationally to improve the fuel mixing with air, and improve in-cylinder combustion. Bamboo-hat shaped combustion system is a new one of those systems taking advantage of spray/wall interaction, and it's combustion, performance and main factors were studied on a two-stroke diesel engine.A spray characteristics-measuring system was established on a fuel injection pump test-bench equipped with electrical-controled high pressure common rail injection system and high-speed video camera. The effects of the diameter of the impingement ring, common rail pressure and impaction distance were studied. The experimental results indicate that, when common rail pressure is above 90MPa, the spray cone angle increases as common rail pressure rise, and the penetration varies slightly during the final stage of the injection. The impaction observably shortens the distance that the spray penetrates during the injection, and extends the maximal spray width. The penetration after impingement increases and the maximal spray width extends with the rise of the common rail pressure. Increase of the height of the impingement ring follows a reduction of the penetration after impingement at the same injection timing, while the distance that the spray penetrates during the injection increases, but still less than the penetration of free spray. Increasing impingement ring height also reduces the maximal width of the impingement spray.The combustion system of a two-stroke marine diesel engine 1E150C was retrofitted to bamboo-hat-shaped spray combustion system and test apparatus established. The combustion and performance experiments were conducted with diesel fuel and its blend with DMC. The heat release rate and...
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