热噪声试验中平板温度边界层对近壁面声压分布影响数值分析

Numerical simulation of temperature boundary layer of a flat panel on the near-wall sound pressure distributions in thermal-acoustic test

为了研究高温平板隔热试件附近温度边界层对近壁面声场的影响,进而对地面模拟试验条件进行适当修正,文章首先构建了热噪声试验中声波穿过温度边界层的简化模型,运用边界层积分法得出常温气体掠过高温壁面时温度边界层内的温度分布;在此基础上,采用有限差分法求解平面波入射非均匀介质时的散射问题,得出高温平板近壁面声压分布。结果表明,温度边界层使近壁面声场发生衰减,在入射声波频率为10 000 Hz时比无温度边界层情况下声压级减小约3 dB,使实际声谱偏离试验条件。

In this paper, a simplified model is built for simulating the sound wave skimming over a hightemperature insulation specimen in the thermal-acoustic testing for studying the influence of the temperature boundary layer on the sound field near the wall. The integration method is used to obtain the temperature distributions in the thermal boundary layer when the room temperature gas sweeps past the high temperature wall. Based on that, the finite difference method is used to solve the scatting problem of the plane wave propagation in an inhomogeneous medium, and the sound pressure distribution near the wall of the hightemperature flat plate is calculated. It is shown that the temperature boundary layer attenuates the sound field near the wall. When the frequency is 10 000 Hz, the sound pressure level in the near wall region is reduced by about3 dB compared with the case without the temperature boundary layer. The result may provide some reference for adjusting or correcting the real test parameters.