强声波作用下煤粉颗粒的振荡特性研究

Study on Oscillation Characteristics of Coal Particles Under Strong Acoustic Waves

考虑Stokes力为颗粒的主要受力,建立了强声波作用下煤粉颗粒的动力学控制方程,并给出了颗粒的夹带系数计算公式。采用数值计算方法研究了颗粒位置、烟气温度、颗粒密度、颗粒粒径、声波频率和声压级等参数对煤粉颗粒在冲击波形成之前运动特征和夹带系数的影响。结果表明:强声波场中距声源不同位置处的颗粒具有不同的振荡周期和速度振幅,呈现出丰富的振荡特征;在声源附近,颗粒主要受基波的影响,表现为类正弦振荡,而在远离声源位置靠近冲击波位置时,颗粒主要受到基波和二次谐波、三次谐波等高次谐波的协同控制,表现为不规则振荡行为;夹带系数与颗粒位置、颗粒质量和声波频率等参数呈负相关,而与烟气温度呈正相关。

Considering the Stokes force as the main force of the particles,the dynamic governor equation of coal particles under the action of strong acoustic waves was established,and the calculation formula of the particle entrainment coefficient was given.The effects of particle position,flue gas temperature,particle density,particle size,acoustic frequency and sound pressure level on the motion characteristics and entrainment coefficient of coal particles before the formation of shock wave were investigated by numerical calculation.Results show that particles at different distances from the acoustic source in a strong acoustic field have different oscillation periods and amplitudes,presenting rich oscillation characteristics.Near the acoustic source,the particles are mainly affected by the fundamental wave,showing a sinusoidal oscillation,when they are far away from the sound source and close to the shock wave formation position,the particles are mainly controlled by the fundamental wave,the second and third harmonics,showing irregular oscillation behaviours.The entrainment coefficient is negatively correlated with particle position,particle mass and acoustic frequency,but positively correlated with flue gas temperature.