为揭示设计工况下低压涡轮级非定常流动特征和气动噪声产生机理，并量化各类现象的湍动能和声能占比，提出了一种基于本征正交分解的低压涡轮气动声源能量评价方法。对低压涡轮级进行了大涡模拟，并对由流场快照组成的时空矩阵进行了本征正交分解。分解出的速度和压力模态对应于导致湍流脉动和气动噪声的相干结构，湍流脉动源和气动噪声源的能量正比于相关模态特征值的总和。结果表明：转静干涉效应引发的势场影响和尾迹周期性迁移是最大的气流脉动源和气动噪声源，其湍动能占比为23.0%且声能占比为39.0%。静叶尾缘涡脱落过程引发的卡门涡街和波包干涉是涡轮级内第二大气流脉动源和气动噪声源，其湍动能占比为3.9%且声能占比为20.9%。动叶叶尖涡脱落过程产生的能量较低，其湍动能占比为3.7%，声能占比为5.6%。

In order to reveal the unsteady flow characteristics and aerodynamic noise generation mechanisms of a low-pressure turbine stage under its design condition and quantify the turbulent kinetic energy and sound energy proportions of various phenomena, a methodology for evaluating the aerodynamic noise source energy of a low-pressure turbine based on proper orthogonal decomposition is proposed. The large eddy simulation was conducted on the low-pressure turbine stage, and the proper orthogonal decomposition was carried out on the spatio-temporal matrixes consisting of flow field snapshots. The velocity and pressure modes correspond to the coherent structures that cause turbulence fluctuations and aerodynamic noise respectively, and the energies of the turbulent fluctuation sources and the aerodynamic noise sources are proportional to the sum of the eigenvalues of the relevant modes. The results show that the potential field influence and wake periodic migration caused by the rotor-stator interaction effect are the largest sources of airflow perturbation and aerodynamic noise, occupying 23.0% of the turbulent kinetic energy and 39.0% of the sound energy. The von Karman vortex street and wave packet interference caused by the stator trailing edge vortex shedding process are the second largest sources of airflow perturbation and aerodynamic noise within the turbine stage, occupying 3.9% of the turbulent kinetic energy and 20.9% of the sound energy. The energy generated during the rotor tip vortex shedding process is relatively low, with the proportion of turbulent kinetic energy being 3.7% and the proportion of sound energy being 5.6%.

V235.1

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