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    • 冷卻塔噪音,冷卻塔如何降噪
    • 本站編輯:杭州菲8平台注册製冷設備有限公司發佈日期:2020-11-02 14:08 瀏覽次數:

    開式冷卻塔正常使用時,風機葉輪高速運轉,風機葉片週期性運動,空氣受到週期性的衝擊,壓力波以聲速傳播而產生噪聲,噪聲隨風機葉片形狀和尺寸的變化,噪聲強度也會不同,若葉輪每秒鐘的旋轉速度爲n(rps)當葉片數爲Z時,其基頻率fc由fc=n×Z決定,H爲風機所提供壓力,要求風機所提供壓力越低即填料靜壓損失低,噪聲則越低,葉輪圓周線速度越低,噪聲就越低。

    When the open cooling tower is in normal use, the fan impeller runs at high speed, the fan blade moves periodically, the air is impacted periodically, and the pressure wave propagates at the speed of sound. The noise intensity varies with the shape and size of the fan blade. If the rotation speed of the impeller per second is n (RPS), when the number of blades is Z, the basic frequency fc is determined by FC = n × Z, and H is the fan The lower the pressure provided by the fan, that is, the lower the static pressure loss of packing, the lower the noise. The lower the circumferential velocity of impeller, the lower the noise.

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    例如雲凌冷卻塔測定一臺300型冷卻塔,採用的風機全壓爲105Pa。根據軸流風機在平面葉柵中環量與流體總壓的變化關係P=PZTN,流經過葉輪後,全壓與空氣密度,葉片數、每個葉型環量和葉輪每秒轉數有關,當全壓確定後,葉片數越多則可以降低風機轉速,轉速在保證風量、保證經葉片風壓的前提下越低,噪聲則越低。

    For example, Yunling cooling tower measures a 300 type cooling tower, the total pressure of the fan used is 105Pa. According to the relationship between the circulation and the total fluid pressure of an axial-flow fan in a plane cascade, P = PZTN, after the flow passes through the impeller, the total pressure is related to the air density, the number of blades, the circulation of each blade type and the speed per second of the impeller. When the total pressure is determined, the more the number of blades, the lower the fan speed. The lower the speed is, the lower the noise will be.

    風機噪聲產生的另一個源頭是空氣壓縮後排出以及葉輪高速旋轉時因氣體邊界層分離而產生的渦流所引起的噪聲,

    Another source of fan noise is the noise caused by the vortex generated by the separation of gas boundary layer when the impeller rotates at high speed,

    渦流噪聲的頻率:F=KV/D(HZ)

    Frequency of eddy current noise: F = kV / D (Hz)

    D----葉片在氣體進口方向的寬度,

    D -- width of blade in gas inlet direction,

    V----葉片相對於氣體的速度,

    V -- speed of blade relative to gas,

    K----常數0.15~0.22

    K -- constant 0.15 ~ 0.22

    葉片葉型弦長越短,風機葉端的速度越小,則渦流噪聲越低。現採用的低靜壓填料,大氣室、多葉片、低轉速等方法來消除風機運轉時所產生的不均勻衝擊波及渦流噪聲。

    The shorter the chord length of blade profile is, the smaller the speed of fan blade end is, the lower the eddy current noise is. At present, the methods of low static pressure packing, atmosphere chamber, multi blade and low speed are used to eliminate the uneven impact and eddy noise generated by the fan operation.