高级检索

    许聪, 刘琪麟, 赖焕新. 亚音速喷流出口扰动对湍流与声场模拟的影响[J]. 华东理工大学学报(自然科学版), 2021, 47(4): 510-518. DOI: 10.14135/j.cnki.1006-3080.20200603001
    引用本文: 许聪, 刘琪麟, 赖焕新. 亚音速喷流出口扰动对湍流与声场模拟的影响[J]. 华东理工大学学报(自然科学版), 2021, 47(4): 510-518. DOI: 10.14135/j.cnki.1006-3080.20200603001
    XU Cong, LIU Qilin, LAI Huanxin. Effects of Flow Forcing on Simulation of Subsonic Turbulent Jet Flow and Noise[J]. Journal of East China University of Science and Technology, 2021, 47(4): 510-518. DOI: 10.14135/j.cnki.1006-3080.20200603001
    Citation: XU Cong, LIU Qilin, LAI Huanxin. Effects of Flow Forcing on Simulation of Subsonic Turbulent Jet Flow and Noise[J]. Journal of East China University of Science and Technology, 2021, 47(4): 510-518. DOI: 10.14135/j.cnki.1006-3080.20200603001

    亚音速喷流出口扰动对湍流与声场模拟的影响

    Effects of Flow Forcing on Simulation of Subsonic Turbulent Jet Flow and Noise

    • 摘要: 采用大涡模拟方法计算出口马赫数Ma=0.75、雷诺数ReD=8.7×105的圆口喷射流动,研究了改进的来流多模态线性不稳定扰动和涡环扰动对促成转捩、湍流特性以及远声场结果的影响。研究结果表明,与来流无扰动的情况相比,两种扰动方式均有利于破坏喷口环状涡的周向稳定性,从而加速剪切层转捩,逼近实际喷口的湍流状态;且多模态线性不稳定扰动工况的喷口速度脉动水平高于涡环扰动下的喷流,能更早地触发转捩。从远声场的结果来看,两种扰动方法有效地减少了计算模型中因转捩和涡配对而导致的低频噪声误差,从而吻合实验数据。

       

      Abstract: The inaccurate nozzle-exit conditions due to the difficulties in measurements make the numerical simulation insufficient to predict the jet development of the laboratory nozzle. Moreover, there is a greater discrepancy for the full-scale turbulent jet. Therefore, the effects of inflow conditions are of great interest again in jet noise recently. Large eddy simulations (LES) of a round jet at Ma=0.75 and ReD=8.7×105 are carried out so as to study the inflow forcing effects on the predicted flow and noise results. A modified multi-mode linear instability forcing method for the inflow is proposed and employed so as to trigger the turbulence. As a comparison, calculations without inflow forcing and with a vortex-ring forcing are also carried out. Numerical results show that both the vortex-ring forcing and the multi-mode liner instability forcing methods are efficient to damage the azimuthal stability of the large scale ring vortices appeared near nozzle exit. This leads to an accelerated flow transition to turbulent shear-layer, which is the exact state of the flow in realistic nozzles. The predicted spectra of the axial and radial velocity fluctuations are compared. It is found that the peak related to flow transition is less distinct for jets with force. Besides, the initial turbulent fluctuations are at higher level with the proposed force compared with the vortex-ring forcing method, resulting in a faster flow transition. Comparison of the predicted sound far fields shows that with the inflow forcing methods, the low frequency noises caused by vortex pairing during transition are suppressed. As a result, theoretical data well match the experimental data for turbulent jets.

       

    /

    返回文章
    返回