叶顶间隙对车用增压器涡轮性能的影响规律研究

Influence of Tip Clearance on Turbine Performance of Vehicle Turbocharger

研究了叶顶间隙对乘用车汽油机增压器涡轮性能的影响规律。研究中设定3种类型的涡轮叶顶间隙变化,分别为单独叶片进口间隙变化、单独叶片尾缘间隙变化及叶片进口间隙与尾缘间隙同步变化,每种类型间隙设定了不同间隙尺寸,在稳态条件下对3种间隙进行模拟。结果显示:叶片进口间隙与尾缘间隙同步变化时对涡轮效率、输出功率及涡轮出口温度影响最大,单独叶片进口间隙变化的影响最小;叶片进口间隙与尾缘间隙同步变化对涡轮输出功率与涡轮出口温度的影响基本是单独叶片进口间隙变化和单独尾缘间隙变化影响的叠加;叶顶间隙对涡轮流通能力的影响不明显;随着间隙尺寸的增大,叶片通道后半部分叶顶附近总压出现高数值区域,涡轮出口马赫数增大,从而降低涡轮的工作效率。

The influence of tip clearance on turbocharger turbine performance of passenger car gasoline engine was studied.Three types of tip clearance changes were designed,including the individual changing of impeller inlet tip clearance,the individual changing of trailing edge tip clearance and the synchronous changing of both.Different sizes were set for each type of tip clearance.Numerical simulation was then carried out under steady condition for the three types of tip clearances.The results show that the synchronous changing of impeller inlet tip clearance and trailing edge tip clearance has the greatest effect on turbine efficiency,output power and turbine exit temperature and the individual changing of impeller inlet tip clearance has the least effect.The influence of synchronous changing on turbine output power and exit temperature is basically the linear superposition of the individual effect of the two tip clearances.The effect of tip clearance on turbine flow capacity is unobvious.With the increase of clearance size,a high-value area of total pressure appears in the latter part of blade passage and the Mach number of impeller exit becomes large,resulting in the turbine efficiency decrease.