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低负荷下的扭矩对于小型发动机十分重要,其决定了汽车的驾驶性能。配有双通道蜗壳的涡轮已被证实在瞬态性能和气缸扫气方面具有极大优势。本研究通过数值方法,比较了不同部分进气条件下双通道径流涡轮的性能。设计了一个双通道径流涡轮,以达到某国外混流涡轮(带有可变喷嘴的涡轮A)的流通能力。借助软件ANSYS-CFX,采用稳态数值模拟方法来实现全部进气和部分进气条件下涡轮的性能预测。基于不同进气条件(叶根进气HI和叶尖进气SI)的性能比较结果进行流动机理分析。结果显示SI比HI具有更好的性能,且传递到叶轮的流动在通道内产生了完全不同的涡流结构。对于HI进气,产生于叶轮叶根处的涡流逐渐迁移到叶尖区域,而SI进气正好相反,这即是HI进气较SI进气具有更高流动损失和更差性能的原因。
Torque at low load is very important for small engines, which determine the driving performance of the car. Turbines equipped with a dual-channel volute have proven to be extremely advantageous in terms of transient performance and cylinder scavenging. In this study, the performance of two-way run-off turbine under different conditions of intake was compared by numerical method. A two-pass radial turbine was designed to achieve the flow capacity of a foreign mixed-flow turbine (turbine A with a variable nozzle). With software ANSYS-CFX, the steady-state numerical simulation method is used to predict the performance of the turbine under all intake and partial intake conditions. The flow mechanism was analyzed based on the comparison of the performance of different inlet conditions (root inlet HI and tip inlet SI). The results show that SI has better performance than HI, and the flow delivered to the impeller creates a completely different vortex structure within the channel. For HI intake, the vortices generated at the impeller root gradually migrate to the tip region while the SI intake is exactly the opposite, which is why HI inlet has higher flow loss and poorer performance than the SI inlet.