3000r/min left side sound intensity contour 000r/min right side sound intensity contour 000r/min rear end sound intensity contour 000r/min top surface sound intensity contour map can be seen from the left side The sound source center of the surface corresponds to the exhaust port of the compressor cylinder, and the intensity level of the contour center point is 8777dB(A), and the contour line converges slowly in the lower abdomen of the compressor, indicating that the compressor There is a large source of noise in the lower abdomen.
There is an suction chamber on the left lower abdomen of the compressor. The distance from the bottom of the mounting bracket is very short, about 50mm. It is easy to form a reflection sound, so it can't be judged whether the sound source of the lower abdomen is inspiratory noise or reflected noise, but it can be seen that it Not the main source of sound. It can also be seen that the noise is radiated outward from the cylinder exhaust port, and the sound intensity level at the center point is 9051dB(A), and the contour of the total exhaust port is sparse and the convergence is slow, indicating total The exhaust port is also a large source of noise.
Spectrum Analysis Through the noise source identification analysis in Section 2, it can be found that the most important radiation part of the noise is the exhaust port of the compressor, so the exhaust noise is the main noise of the compressor. The fundamental frequency of exhaust noise is the exhaust frequency of the compressor, and the extension of the fundamental frequency and its higher harmonics appears in the entire exhaust noise spectrum. The frequency of the compressor exhaust noise is calculated as follows f=ni60k(1) In the formula, the number of k harmonics, the number of compressor revolutions, and the number of r/mini blades are based on the general rule that the periodic signal is expanded to the Fourier series. As the harmonic order k value increases, the noise level will rapidly decrease. In addition to the fundamental noise and its higher harmonic noise, the exhaust noise also includes the air column resonance noise present in the exhaust pipe, the turbulent noise at the inner wall of the exhaust system pipe, etc. In addition, the exhaust noise includes Airflow injection impact noise. The radiated noise of the compressor casing is mainly affected by the broadband exhaust noise, which easily excites vibration and generates noise.
After the compressor is equipped with a small hole muffler, the sound pressure levels of the three speeds of 1200r/min, 1800r/min and 3000r/min are greatly reduced. The lower the speed, the larger the noise reduction, 1200r/min left. The side is reduced by more than 12dB. From the experimental results, it can be concluded that the noise reduction effect of the two small hole mufflers is almost the same, and the metal mesh small hole muffler is slightly better.
Conclusion In the compressor noise control, two kinds of exhaust small hole mufflers are designed by analyzing the noise reduction characteristics of the small hole muffler and the generation mechanism of exhaust noise: metal mesh small hole muffler and metal perforated plate small hole muffler. The results show that the noise reduction effect of the two small-hole muffler is very obvious. The reduction of the speed at 1200r/min exceeds 12dB(A), and the noise reduction effect is relatively good.
Combined Flow Closed Cooling Tower
Closed Cooling Tower is operated by circulating water or fluid, which is divided into two closed loops.
1. Circulation in the tower: the circulating water or fluid passes through the hot zone environment. After the water temperature rises, it enters the surface cooler in the tower, and the heat is sent to the environment outside the tower through the surface cooler and ventilation fan. The cooled circulating water or fluid is sent to the heat source by the water pump.
2. Circulation outside the tower: the spray water is sent to the spray system by the water tank through the water pipe. After spraying, the spray water first exchanges heat with the filler, so that the spray water can be cooled rapidly. At this time, the water contacts the surface of the surface cooler for heat exchange. Part of the hot steam is discharged through the ventilation fan, and the cooled spray water drops to the water tank for secondary circulation to form an external circulation for cooling.
Combined Flow Closed Cooling Tower,Bac Cooling Tower,Cooling Tower Systems,Chiller Tower
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