DPM-LES investigation on flow field dynamic and acoustic characteristics of a twin-fluid nozzle by multi-field coupling method

Abstract

Dust particle pollution endanger human health and cause safety hazards in industry. Twin-fluid atomization technology plays an important role in reducing the pollution of dust particles. In the current study, based on the Large Eddy Simulation (LES) model, the Discrete Phase Model (DPM) model and the Ffowcs Williams-Hawkings (FW-H) model, a fluid-solid-acoustic multi-physics coupling DPM-LES model is proposed, and the numerical simulation results under the multi-field coupling are compared and verified by experiments. Then, through the numerical simulation method, the flow field dynamic characteristics and acoustic characteristics inside and outside the gas-liquid twin-fluid nozzle (TFN) under different operating parameters and self-excited vibrating cavity (SVC) structure parameters are studied. Because the high-frequency vibration of the SVC caused by high gas flow leads to local severe turbulence and the rebound effect between the fluid and the SVC, the dynamic pressure value in most areas of the nozzle reached more than 7000 Pa. Due to the resistance of the air in the flow field and the friction and entrainment between the gas-liquid two phases during the movement, the axial distance in the atomizing flow field with a velocity exceeding 2 m/s can be as far as 2.13m when orifice depth L =1.0 mm. The SPL of the nozzle is gradually attenuated in the process of space propagation. The increased gas flow enhances turbulence, which intensifies nozzle noise. In this paper, the DPM-LES investigation on flow field dynamic and acoustic characteristics of a TFN by multi-field coupling method are studied, which can lay a theoretical foundation for the optimal design of TFN in engineering and provide a certain reference for the reduce of dust particle pollution.