The noise of the fan noise fan depends on the structure, flow, total pressure and speed of the fan. The evaluation of common fan noise is the sound power level and the specific sound power level and its frequency characteristics. According to the "Design Guide for Practical Heating and Air Conditioning", the total sound power level of the ventilator is played (dB). The best operating point of the same fan is its highest efficiency point, which is also the lowest point of the sound power level. Sound power level gas (dB) of axial flow fan: play = 19 + 10 lgQ + 25 lgH + accounted for (2), Q - air volume, power account; H - wind pressure, Pa; accounted for - working condition correction value. It can be seen from (1) and (2) that the noise of the fan is mainly related to the air volume and wind pressure. The airflow noise is mainly related to the wind speed, cross-sectional area and wind speed of the wind tunnel. The design can be based on the technical measures for heating and ventilation of civil buildings. 》Select the appropriate wind speed. The vibration of the fan when the fan is running is vibrating during operation. During the design, measures must be taken to control the vibration. Otherwise, solid sound will be generated, which will cause vibration of the air duct support and hanger. Specific measures to reduce noise Fan selection Because the centrifugal fan is arranged on the ground, a separate fan room is required, which occupies the parking space of the garage. The builder generally does not agree to set up the fan room. Therefore, most of the design is the axial flow fan. We will not discuss centrifugal fans. There are many types of axial flow fans, such as exhaust axial fan, mixed flow axial fan, T35 axial fan, SF post axial fan. In the design, the axial flow fan with less noise must be selected as much as possible according to the actual situation. The underground garage of the high-rise building is equipped with the usual air exhaust system, the smoke exhaust system and the air intake system during the fire. If two systems are considered in the design, the pipeline is more complicated, and the underground garage has a lower floor height, and there is not enough space under the garage roof. Pipes, two casing roads have a large investment. In the design, only one set of piping system, that is, the exhaust and exhaust system can be considered. Therefore, the smoke prevention zone may not be divided in the fire zone. Since the amount of exhaust air and the amount of smoke exhausted in the same fire compartment are the same, the same wind turbine can be selected for both exhaust and exhaust. Taking into account the special requirements of mechanical smoke exhausting, the design is to use a high-temperature exhaust smoke axial flow fan, usually exhausting the air, and exhausting smoke during a fire. However, due to the high noise and high power consumption of the high-temperature exhaust fan, the design chose two fans to share a set of air duct system operation: that is, a mixed-flow axial fan usually vents air, and a high-temperature exhaust fan fires. smoke. Usually, only the mixed-flow fan is exhausted, and the mixed-flow fan is turned off during the fire, and the high-temperature exhaust fan is exhausted. In this way, the noise when the fan is running normally is much lower than that of the exhaust fan that is normally used. The blower can be used with a mixed flow axial flow fan, which can be used in normal times and in fire. The air supply volume of the garage is calculated according to the air volume of not less than 5 times/h, and the air volume of the smoke is required to be 50% of the amount of smoke exhausted. Therefore, when the fan is designed, it can be selected according to the air volume required for normal ventilation. Before selecting the fan, the resistance of the system and the required air volume should be accurately calculated. The fan should be selected according to the air volume and wind pressure, and the working point should be placed in the area where the fan is efficient. At this time, the noise of the fan is also low, so the fan should be operated in a good performance area regardless of the fan noise or the efficiency of the fan. Airflow noise control When designing the duct section, it is very important to control the wind speed in the pipeline. It is known from P=r and g that the system pressure is proportional to the square of the airflow velocity in the pipeline, the speed increases, and the pressure increases accordingly, resulting in the system The noise increases, so the wind speed inside the pipeline should be controlled as much as possible on the system piping, especially the ventilation and air conditioning pipelines of civil buildings. According to the "Technical Measures for Heating and Ventilation of Civil Buildings", the wind speed of the main pipe is generally controlled at 7 lom/s. Reverse Plain Dutch,Reverse Plain Dutch Weave,72 X 15 Mesh Reverse Plain Dutch,152 X 24 Mesh Reverse Plain Dutch Anping Guangtong Hardware Wire Mesh Co.,Ltd , https://www.apguangtong.com