脉冲频率对径向涡轮转子进口流动特性的影响

可调涡轮增压器涡轮转子进口的动静干涉效应以及脉冲气流的波动使得转子进口流动更为复杂，进而影响转子通道内的气体流动。为了更好地了解脉冲频率对涡轮转子进口流动特性的影响,应用ANSYS CFX软件对不同频率(20、40、60 Hz和80 Hz)脉冲进气条件下的全周径向可调涡轮模型进行数值模拟,并通过试验数据对数值模型进行了验证,得出转子进口平均气流角在一个脉冲周期内的分布规律以及气流角在周向和叶高方向的分布规律。发现脉冲频率对低压侧转子进口入射角影响更大,脉冲频率越低,低压侧的转子进口负入射角越大;周向绝对气流角分布规律相似,波动幅度基本相同;相对气流角在压力下降沿波动更稳定。 

Influence of pulsating frequencies on characteristic of radial turbine rotor inlet flow

Detailed understanding of the flow interaction within the complex geometry of turbine stage coupled with the imposed unsteady pressure waves was presented. A fully validated numerical model was established based on ANSYS CFX code. For this purpose, four unsteady simulations of 20, 40, 60 and 80 Hz together with the steady state simulations were conducted. The flow angle distribution in a pulsating cycle and at the circumferential and spanwise positions was analyzed in different pulsating frequency conditions. The results showed that the pulsating frequency mainly affected the inlet incidence angle of rotor at the high pressure side, moreover, the lower the pulse frequency, the greater the negative incident angle of the low pressure side. It was also found that the absolute flow angle distribution at circumferential potion was similar and the relative flow angle fluctuations during the pressure decrements instances was significantly lower as compared with that during pressure increment instances.