Abstract
Four subgrid-scale models based on large eddy simulation (LES), such as Smagorinsky–Lilly (SL), dynamic Smagorinsky–Lilly (DSL), wall-adapting local eddy-viscosity (WALE), and dynamic kinetic-energy transport (KET) were used and couple Ffowcs Williams–Hawkings equation to accurately analyze and identify the characteristics and position of the sound sources of rod–airfoil interaction. The results of four models were compared with experimental data. It was found that the DSL model was the optimal subgrid-scale model for the study of the interaction noise considering the calculation accuracy. Therefore, the DSL model was selected for analyzing and identifying the characteristics and location of the interaction noise source. During the calculation, solid and permeable data surfaces were used for acoustic integral surfaces. The results show that the impact of the quadrupole source is negligible at a low Mach number, and the dipole noise coming from the pressure fluctuations is dominant. Meanwhile, the dipole noise from the airfoil is louder than that from the rod; the leading edge of about 30% chord length of airfoil the is the main sound source of interference effect. Above results can provide guidance for research of blade-vortex interaction noise.
Highlights
The noise generated by the mutual interference effect between upstream wakes and downstream blades, such as aircraft engine rotor/stator interaction noise, ventilator, helicopter blade-vortex interaction noise, etc., is a common phenomenon in the industrial field [1]
It can be observed that the rod drag coefficient in the dynamic Smagorinsky–Lilly (DSL), wall-adapting local eddy-viscosity (WALE), and kinetic-energy transport (KET) models fluctuate around 1, whereas the rod drag coefficient of the SL model is over predicted by about 30 % during the time step of 10,000 - 20,000
SL, DSL, WALE, and KET subgrid-scale models have been used to study the characteristics of rod–airfoil interaction flow field and far sound field
Summary
The noise generated by the mutual interference effect between upstream wakes and downstream blades, such as aircraft engine rotor/stator interaction noise, ventilator, helicopter blade-vortex interaction noise, etc., is a common phenomenon in the industrial field [1]. Owing to its simple structure, the rod–airfoil model is considered a simplified interaction model for investigating rotor/stator interaction noise [2]. Different subgrid-scale models will result in different flow details, and the accuracy of acoustic far-field depend on the flow field. Many scholars studied the influence of different subgrid-scale models on flow field details [3,4,5,6], there are few comparative studies on different subgridscale models of the accuracy for interaction noise. It is necessary to select the most suitable subgrid-scale model in the follow-up study on noise characteristics and sound identification. Regarding the influence of quadrupole noise under low Mach, the number conclusions obtained in different literatures are not consistent [6, 7]
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