Under the above assumptions, the finite element equation can be known from the acoustic theory. At this time, the sound pressure in the factory meets the Helmholts wave equation 2c2p+2p=0. The 2 Laplace operator in the p-compressor plant sound pressure vibration circular frequency c air The sound velocity is obtained by the sound pressure wave equation and the dynamic equation of structural vibration. The finite element equation of the acoustic-structure coupling vibration in the compressor building is <3>MX+CX+KX=F(t) where M, C, and K are respectively The mass, damping and stiffness matrix of the acoustic-structure coupled vibration system; F(t) is the excitation force vector. The finite element meshing 6HHE-VE6 compressor building has a length of 24m, a width of 18m and a height of 10m, wherein the height of the middle section in the width direction is 115m; the size of the control room is 63m42m5m; and the size of the distribution room is 40m61m5m. The size of the corridor is 40m61m5m; a 6HHE-VE6 compressor is placed in the factory, and its size is the same as that of the test surface in the literature <3>. In this paper, the 6HHE-VE6 compressor plant is divided into 27,034 Fluid30 uncoupled units and 6682 Fuild30 coupling units by means of map meshing. The finite element model of the discrete plant is shown in the figure, where the positive X-axis is positive east. Model parameters Since the chamber medium of this plant is air, the parameters of the air medium are: air density 129kg/m3; sound propagation speed in air is 340m/s; sound absorption coefficient of wall and ground on the boundary, according to experience Take 004; the sound absorption coefficient at the window (middle purple part) is approximately 070 according to experience. Three-dimensional sound field finite element modal analysis In this paper, the modal calculation and analysis of the three-dimensional sound field of 6HHE-VE6 compressor building is carried out by asymmetric solution method, and the natural frequency and mode shape of the sound field of the plant are obtained. The first 10 natural frequencies of the plant are given, and the first, third and fourth modes of the plant are given. Three-dimensional sound field finite element response analysis 331 load It is known from the literature that the compressor exhibits a dominant frequency noise at 1000 Hz, so the result of the test in the 1000 Hz band is applied to the hypothetical test surface <4> of the 6HHE-VE6 compressor. 067768Sin(2000t)Pa, adding UX, UY, UZ to zero at the boundary of the plant, analyzing and calculating the sound field response distribution of the 6HHE-VE6 compressor building at this frequency. In addition, the response of the three-dimensional sound field of the plant with 067768Sin (25t) Pa and 20Sin (2000t) Pa is analyzed and calculated. Conclusion The finite element analysis method is used to respond to the distribution of sound field in the compressor building of 6HHE-VE6 compressor plant at 1000 Hz. The response of the compressor building at the external load frequency of 125 Hz is in response to the sound field distribution. The compressor building responds at an external load frequency of 125 Hz. Sound field pressure distribution (unit: Pa) The three-dimensional sound field modal analysis and response analysis of the compressor building in response to sound field distribution at 2Sin(2000t)Pa provides a theoretical basis for the acoustic design and noise analysis of the plant. From the finite element modal analysis and response analysis of the sound field, it can be known that: (1) the acoustic natural frequency of the plant is low, and as the modal order increases, the acoustic mode shape of the plant tends to be complicated; (2) The excitation frequency of the compressor falls just in the third-order resonance zone and the fourth-order resonance zone of the plant, indicating that the sound field of the plant will have acoustic resonance; (3) the plant responds with the increase of the external load amplitude. The sound pressure level value also increases, but the magnitude of the increase is not large; (4) when the external load frequency is low and near the acoustic natural frequency, the response sound pressure level of the sound field is larger than that at the high frequency.
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