# Investigation on Characterization of Typical Characteristic in Compressor Based on Flat Plate Model
## 1 Introduction
[PERSON] indicated that the force generated by the action of the solid boundary on the flow field exists in the form of a dipole force source term, which makes the main contribution to the sound field in the flow channel, i.e., the so-called dipole sound source [25]. After proposing [PERSON]'s acoustic analogy equation, researchers try to solve the flow field where the structure is located and use the acoustic analogy equation to equivalent the aerodynamic force generated by the solid surface as the sound source term, so achieving the solution of the flow-induced sound source. This solution method has been successfully applied in the flow-induced sound generation of structures such as plates, cylinders, and airfoils with good calculation results [26; 27]. A dipole force source will be generated by the function of counterforce in the flow field under the action of the solid wall, and this force will also exist in the flow field information. Therefore, the accurate description of the aerodynamic force caused by the solid wall is the key point to solving the problem of the sound generated in the wake of the structure. The relationship between the aerodynamic force on the surface of the structure and the flow vortex in the flow field can be explained by the Blasius theory. So, there is no need to solve the surface force of the structure. [PERSON] did a more authoritative verification in this regard [28]. [PERSON] first used the large eddy simulation method to complete the calculation of the flow field information around the structure and obtained the Lighthill stress information on the flow field calculation grid. Then, by interpolating the flow field information into the sound field calculation grid, the solution of the sound field information was achieved [29]. Under the current situation of the rapid development of computer technology, especially the realization of large-scale and ultra-fast parallel computing, the direct numerical calculation method used to directly calculate the sound field information can be achieved to a certain extent [30]. However, the solution of the directly coupled solution method and the sound field with the flow field requires a lot of computing resources, and it is difficult to widely apply it in practical engineering applications. Therefore, it is technically feasible and practical to develop a reliable and effective solution method for flow-induced sound generation. In the paper, the combination of large eddy simulation and acoustic analogy method, which is used to solve the problem of sound generated with shedding vortex from the trailing edge of a flat plate locked in a rectangular pipe, will be a good solution to the problem of turbulent sound. The noise experiment between compressor stages is conducted in present research. The frequency spectrum characteristics, sound pressure level, and phase relationship of the noise signal corresponding to the abnormal vibration of the rotor blade are captured,and the feature of \"frequency locked\", which is consistent with the acoustic resonance in the compressor is obtained. Based on the Parker model, an acoustic analogy research method used to study the characteristics and mechanism of the acoustic resonance of the sound induced in the pipe cavity is proposed. Taking this method to analyze the acoustic mode distribution characteristics and \"frequency locked\" characteristics of the pipe cavity, and reveal the mechanism of the acoustic resonance induced by the shedding vortex. The method proposed in the paper is suitable for solving the acoustic problem of the pipeline cavity under the flow conditions of low Mach number and high Reynolds number, which can provide guidance for the investigation of the acoustic resonance mechanism in an aeroengine compressor.