【摘要】 为一台带可变涡流进气道的缸内直喷汽油机建立了三维数值模型,对其在2 000和5 500r/min全负荷工况和涡流调节阀开启与关闭不同状态下的进气、喷雾和混合气形成过程进行数值模拟。结果表明:通过涡流调节阀开启和关闭可以改变进气门周围进气流动速度分布,进而调节缸内滚流强度。在低转速时,涡流阀关闭使缸内滚流强度明显提高,达涡流阀开启时的4～6倍;关闭涡流阀产生的大滚流强度加快了缸内燃油雾化速度,有助于在点火时刻形成浓度均匀一致的混合气。但在高转速时,关闭涡流阀使进气道流通能力受到抑制,缸内进气质量仅为涡流阀开启时的2/3,且过大的湍动能也不利于稳定燃烧。更多还原

【Abstract】 A 3D numerical model for an in-cylinder direct injection gasoline engine with variable swirl intake port is established and a numerical simulation on its induction,spray and mixture forming processes under a condition of full load at 2000r/min and 5500r/min rotating speeds with swirl control valve(SCV) open and close states.The results show that switching the open and close state of SCV can change the distribution of induction flow velocity around intake valve and hence control the tumble intensity in cylinder.At low rotating speed,closing SCV will markedly increase the tumble intensity up to 4~6 times as high as that with SCV opened,and the higher tumble intensity caused by closing SCV will accelerate the atomizing speed of fuel in cylinder,being conducive to the forming of mixture with uniform concentration.But at high speed,closing SCV will restrain the flow passing through intake port with a mass of charge in cylinder reduces to only two third of that with SCV opened,and too large a turbulent kinetic energy is also detrimental to stable combustion.更多还原