###### Abstract  
This paper concerns the application of a linear microphone array in the quantitative evaluation of blade trailing-edge (TE) noise reduction. The noise radiation from the blades with straight and serrated TEs is measured in an indoor open-jet wind tunnel. The array data are processed using the inverse method based on the Clean algorithm based on spatial source coherence (Clean-SC). In order to obtain correct application and achieve the best effect for the microphone array test, the computing software for array data reduction is firstly developed and assessed by [PERSON]'s benchmark case. The assessment results show that the present array data processing method has a good accuracy with an error less than 0.5 dB in a wide frequency range. Then, a linear array with 32 microphones is designed to identify the noise source of a NACA65(12)-10 blade. The performance of the Clean-SC algorithm is compared with the Clean algorithm based on point spread functions (Clean-PSF) method for experimentally identifying the noise sources of the blade. The results show that there is about a 2 dB error when using the Clean-PSF algorithm due to the interference of different aerodynamic noise sources. Experimental studies are conducted to study the blade TE noise reduction using serrated TEs. The TE noise for the blade with and without sawtooth configurations is measured with the flow speeds from 20 m/s to 70 m/s, and the corresponding Reynolds numbers based on the chord are from 200,000 to 700,000. Parametric studies of the sawtooth amplitude and wavelength are conducted to understand the noise reduction law. It is observed that the TE noise reduction is sensitive to both the amplitude and wavelength. The flow speed also affects the noise reduction in the serrated TEs. To obtain the best noise suppression effect, the sawtooth configuration should be carefully designed according to the actual working conditions and airflow parameters. broadband noise reduction; trailing edge noise; serrated configuration; microphone array; Clean-SC 2  
[PERSON] [7], [PERSON] [8; 9], [PERSON] [10; 11], [PERSON] [12], and [PERSON] [13]. Based on the above theoretical studies, the TE noise was also studied experimentally by [PERSON] et al. [14; 15] and modeled analytically by [PERSON] [16; 17] and [PERSON] [18]. The TE noise reduction has been an important focus for many years [19]. The silent flying owls provide great inspiration for aeronautical scientists to design quieter vehicles [20; 21]. Inspired by the quiet flying owls, porous modifications [22; 23; 24] and flexible brushes [25] have been used for noise reduction. In this study, we use another noise reduction treatment named serrated TEs which have been initially modeled by [PERSON] [26; 27]. Both sinusoidal [26] and sawtooth TEs [27] were theoretically studied by [PERSON], and considerable noise reduction was obtained for both treatments. After [PERSON]'s work, many experimental investigations were conducted to explore the noise benefits of the serrated TEs, and the serrated treatments were proved to be an effective noise control configuration [28; 29]. However, it was found that [PERSON]'s serration model over-predicts the noise reduction effect in the high-frequency range, while it under-predicts the noise reduction effect in the low-frequency range [30]. It is proposed that the flow and acoustic mechanism of the realistic airfoil and turbodinchinery blade are more sophisticated than that of the semi-infinite plane used by [PERSON] due to the loading distribution and the flow turning. Especially, there is a complicated interrelationship between the LE flow and TE flow for the realistic blade due to the small chord [30]. The LE and TE noise sources always arise simultaneously, and these two sources are always very close to each other. In order to explore the noise generation mechanism of LE and TE noise, and to assess the noise reduction effect of the noise control treatments, it is necessary to separate and quantify the airfoil LE and TE noise source.