本文采用非线性谐波法与定常计算方法,对离心压气机的内部流场进行了数值模拟,对比了时均流场与定常流场的差别,研究了离心压气机确定应力分布的特点。结果表明,采用非线性谐波方法所得到的压气机内部流场宏观结构与定常结果基本一致,但流场参数分布细节存在较明显差别,且这种差别与对应的确定应力场的分布特征吻合,验证了确定应力是引起时均流场与定常流场差别的原因。对确定应力的分布特征分析表明,离心压气机内确定应力在流向上呈现为从叶轮出口向上下游逐渐递减的趋势,在叶高方向上表现为从叶根到叶顶逐渐递增趋势;且在整体上,确定应力的空间不均匀特性在叶轮出口处最为强烈,表明离心压气机内部最强非定常效应同样位于叶轮出口。
Numerical simulation on a centrifugal compressor is carried out to investigate the differences of flow fields between time-averaged and steady state as well as the distribution characteristics of deterministic stress.It is found that the macro flow structure of time-averaged and steady flow field is generally similar but flow details differ a lot.The differences in flow details are identical to the distribution of the deterministic stress,which improves the facts that deterministic stress is the reason of leading the differences between time-averaged and steady flow behavior.Results also show that the deterministic stress increases along spanwise gradually and is in high level and with strong-variation in the region near impeller exit,which reveals strong flow unsteadiness in corresponding region,caused by strong tip leakage vortex and secondary flow vortex.
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