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在充满二元混合气体的声波谐振管中,振荡的气体会在径向上建立振荡的温度梯度,径向的温度梯度会引起两种组分的分子沿着不同方向进行扩散,在这种热扩散效应和热声效应的共同作用下,声波能够把混合气体中的两种组分分别带向谐振腔的速度节点和压力节点,使得混合气体在声波传播方向上逐渐分离。为了研究热声分离过程的机理,本文对一个半波长的声波谐振管进行了二维的建模,并基于可压缩的SIMPLE算法,通过求解He-Ar混合气体的速度场、温度场和一种组分的浓度场,对谐振腔内的传热传质过程进行了详细的数值模拟研究。数值模拟结果与文献的理论计算值进行了比较,结果符合良好。随后,通过研究一个周期内径向上的温度、速度和Ar的摩尔分数分布,揭示了径向上的热扩散过程,以及中间气体与边界层内气体之间的热质交换过程,完整地解释了热声分离过程的发生机理。
In a bimodal mixed gas acoustic resonance tube, the oscillating gas establishes an oscillating temperature gradient in the radial direction. The radial temperature gradient causes the molecules of both components to diffuse in different directions. In this thermal diffusion Effect and thermoacoustic effect, the acoustic wave can bring the two components of the mixed gas to the velocity node and the pressure node of the resonant cavity, respectively, so that the mixed gas is gradually separated in the acoustic wave propagation direction. In order to study the mechanism of thermoacoustic separation, a half-wavelength acoustic resonator was modeled in two dimensions. Based on the compressible SIMPLE algorithm, the velocity field, temperature field and a Component concentration field, the heat transfer in the resonant cavity mass transfer process conducted a detailed numerical simulation. The numerical simulation results are compared with the theoretical calculations in literature, and the results are in good agreement. Subsequently, by studying the radial temperature, velocity and the molar fraction distribution of Ar during one cycle, the thermal diffusion process in the radial direction and the heat and mass exchange process between the intermediate gas and the gas in the boundary layer are revealed, which completely explain the thermal sound The mechanism of the separation process.