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深度调峰下声波对煤粉颗粒对流传热特性的影响研究

Investigation of the Effect of Acoustic Waves on the Convective Heat Transfer Characteristics of Coal Powder Particles under Deep Peak Adjustment

  • 摘要: 为提高煤粉燃烧的传热效率,本文通过数值模拟方法,探究了声波参数对煤粉颗粒周围对流传热过程的影响。研究发现:声波扰动可以有效增强升力与阻力系数的振幅,振幅随声压级和声频率的升高而增大,从而加剧了颗粒尾部的漩涡脱落。声波的加入使漩涡脱落频谱中出现了多个规律峰值,漩涡脱落主频随声频率增大而增大,其峰值振幅随声压级的增大而增大。声波通过破坏热边界层和促进漩涡脱落来强化传热,并提出声波参数的主导效果取决于声雷诺数与背景流雷诺数之比ε:在0.49<ε<1.94范围内,局部努塞尔数的分布主要受声压级影响;在3.87<ε<7.73范围内,声频率的影响则转变为更为主导的因素。本研究揭示了声波参数对煤粉颗粒周围对流传热过程的耦合影响机制,为提高煤粉燃烧传热效率提供了理论参考。

     

    Abstract: This study employs numerical simulations to investigate the influence of acoustic parameters on convective heat transfer around coal particles, aiming to enhance heat transfer efficiency in pulverized coal combustion. The results reveal that acoustic pulsations significantly amplify the amplitudes of both lift and drag coefficients—amplitudes that increase with higher sound pressure levels (SPL) and frequencies—thereby intensifying vortex shedding at the particle rear. The introduction of acoustic waves induces a multi-peaked frequency spectrum in vortex shedding: the shedding frequency increases with acoustic frequency, while the peak amplitudes grow with rising SPL. Acoustic waves enhance heat transfer by disrupting the thermal boundary layer and promoting vortex shedding. It is further proposed that the dominant effect of acoustic parameters is governed by the ratio ε of the acoustic Reynolds number to the background flow Reynolds number: within the range 0.49 < ε < 1.94, the local Nusselt number distribution is primarily influenced by SPL; whereas within 3.87 < ε < 7.73, acoustic frequency becomes the dominant factor. This research elucidates the coupled mechanisms by which acoustic parameters affect convective heat transfer around coal particles, offering theoretical insights for improving heat transfer efficiency in coal combustion systems.

     

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