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采用定常与非定常数值模拟方法,对某小型离心压气机进行数值计算,首先比较了定常结果与非定常时均结果的特性;然后结合离心叶轮出口和径向扩压器进口典型位置非定常压力脉动的频域特性,研究了离心叶轮与扩压器之间的转静干涉作用;最后着重分析了离心叶轮带与不带分流叶片对径向扩压器进口压力脉动频率特性的影响。结果表明:在相同流量下,非定常时均结果的压比偏高约3.7%,效率偏高0.1%;在带有分流叶片的离心压气机中,离心叶轮叶片出口与扩压器叶片进口的脉动除了叶片通过频率的非定常脉动外,分流叶片尾缘会产生与之强度相当的2倍叶片通过频率的非定常压力脉动。同时,分流叶片会对径向扩压器进口产生更强的0.5倍叶片通过频率非定常压力脉动,这些频率的非定常压力脉动很可能会对离心压气机叶片的疲劳强度造成影响。
The numerical simulation of a small centrifugal compressor is carried out by using the method of steady and unsteady numerical simulation. Firstly, the characteristics of steady-state results and unsteady time-averaged results are compared firstly. Then, combining the centrifugal impeller exit and radial diffuser inlet typical position unsteady pressure The effects of centrifugal impeller and diffuser on the pressure pulsation frequency characteristics were analyzed emphatically. Finally, the influence of centrifugal impeller with and without splitter blades on the pressure pulsation frequency characteristics of radial diffuser was analyzed emphatically. The results show that under the same flow rate, the pressure ratio at unsteady time is about 3.7% higher and the efficiency is 0.1% higher. In the centrifugal compressor with splitter blades, the outlet of the centrifugal impeller blades and the inlet of the diffuser blades Pulsation In addition to the unsteady pulsation of the blade passing frequency, the splitter blade trailing edge produces unsteady pressure pulsations of 2 times the blade passing frequency with an intensity equivalent thereto. At the same time, the splitter blades produce a stronger 0.5 times blade pass frequency unsteady pressure pulsation of the radial diffuser inlet, and unsteady pressure pulsations of these frequencies are likely to have an impact on the fatigue strength of centrifugal compressor blades.