The slat of a high-lift wing can be a significant noise source during approach and landing. This paper describes an experimental study of the effects of two passive devices (namely, slat extensions and a cove filler) on the aerodynamics and acoustic radiation from a 30P30N model. Test conditions include three effective free-air angles of attack of 5.5, 7.5, and 13 deg, as well as three Reynolds numbers of 1.2, 1.5, and $1.71\times {10}^6$. Steady surface pressure measurements are used to assess the aerodynamics near the midspan section. Unsteady surface pressure and far-field acoustic array measurements are performed to evaluate the near- and far-field pressure fluctuations, respectively. Delay-and-sum beamforming is applied to localize the noise sources and to provide integrated spectra. The slat cusp extensions barely affect the mean $C_p$ distribution, whereas the longest extension achieves up to a 5.4 dB reduction in the overall sound pressure level. The slat-cove filler yields an even higher noise reduction that is lower than the baseline by up to 14 dB. Even though the aerodynamic assessment of the cove filler is incomplete due to the covered pressure ports, the mean $C_p$ distribution over the remaining surface of the model indicates a rather small change compared with the baseline measurements.

在进场和着陆期间，高升力机翼的缝翼可能是一个重要的噪声源。本文描述了两个无源装置（即缝翼延伸部和凹形填充物）对 30P30N 模型的空气动力学和声辐射影响的实验研究。测试条件包括 5.5、7.5 和 13 度的三个有效自由空气攻角，以及三个雷诺数 1.2、1.5 和$1.71\times {10}^6$. 稳定的表面压力测量用于评估中跨部分附近的空气动力学。执行非稳态表面压力和远场声阵列测量以分别评估近场和远场压力波动。延迟求和波束成形用于定位噪声源并提供综合频谱。板条尖端延伸几乎不影响平均值$C_{磷}$分布，而最长的延伸实现了高达 5.4 dB 的整体声压级降低。slat-cove 填料产生更高的降噪效果，比基线低 14 dB。即使由于压力端口被覆盖，凹形填料的空气动力学评估不完整，平均$C_{磷}$ 与基线测量值相比，模型剩余表面上的分布表明变化相当小。