直流风扇基础

*,Copyright,2004 AVC Corporation,直流風扇,基礎,艾奇,2004,年,8,月,1,風扇編碼原則,2,風扇分類,Axial Fan-air flows axially.,Centrifugal Fan(Blower)-air flows radially.,Cross Fan-air flows across the axis.,3,Sleeve Bearing,結構,4,Two Ball Bearing,結構,5,1B1S Bearing,結構,6,Hydraulic Bearing,結構（一）,7,Hydraulic Bearing,結構（二）,8,裝配示意圖,9,Ball Bearing,10,Sleeve Bearing,11,伯努利一元流動方程,伯努利方程的實質：在穩定一元流動的風機進出口管路系統中，風機葉輪傳給氣體的機械功，用於壓縮氣體，使氣體的動能和位能產生變化，並克服流動損失。如為理想氣體，流動損失為,0,，進一步簡化為：,P/,+C2/2 =,常數,12,風扇的全壓,全壓,Ptf,氣流在某一點或某一個截面上的總壓等於該點或截面的靜壓與動壓之和，而風機的全壓，則定義為風機出口截面上的總壓與進口截面上的總壓之差，即,Ptf,=(Psf2+,2,*C2*C2/2)-(Psf1+,1*,C1*C1/2),13,風扇動壓,動壓,Pdf,風機出口截面上氣體的動能所表征的壓力。,14,風扇靜壓,靜壓,Psf,風機的全壓減去風機的動壓，即：,Psf,=(Psf2-Psf1)-,*C1*C1/2,風機的靜壓既不是風機出口截面上的靜壓,Psf2,，,也不等於風機出口截面與進口截面上的靜壓差,(Psf2-Psf1),。,15,風扇特性,16,風洞示意圖,17,PQ DATA,18,PQ Curve,19,Efficiency curve,20,Speed curve,21,系統阻抗及工作點,Every system has an impedance curve.System impedance is generally proportional to Q,2,.Operating point is the intersection of P-Q curve and the impedance curve.The use of impedance curves is to select a fan that provides maximum air flow rate at the operating point.,22,風扇的並列與串聯,For identical fans in serial,P,max,=P,max,single,Q,max,=Q,max,single,x no.of fans,For identical fans in parallel,Q,max,=Q,max,single,P,max,=P,max,single,x no.of fans,23,噪聲,Sound Pressure Level(SPL),SPL=20 log(P/,P,Ref,)Unit:dB,where P=pressure,P,Ref,=a reference pressure,(,2E-5 Pa),A weighted sound pressure level(,dBA,),Human ear responds to sound differently at various frequencies.,24,風扇噪聲（一）,Noise levels:,0,to,20,dBA,Very Faint,20,to,40,dBA,Faint,40,to,60,dBA,Moderate,60,to,80,dBA,Loud,80,to 100,dBA,Very Loud,100,to 140,dBA,Deafening,Noise Change:,3dB Just noticeable,5dB Clearly noticeable,10dB Twice(or half)as loud,25,風扇噪,聲（二）,噪聲主要分為兩類，旋轉噪聲與旋渦噪聲。,旋轉噪聲產生的機理,：葉片通道出口處，沿周向的氣動壓力與氣流速度發生很大變化，旋轉的葉片通道掠過較窄的中蝸舌處，出現周期性的壓力和速度脈動所產生的噪聲；,另外，葉片鄰近的固定位置，空氣受到葉片及其壓力場的周期性激勵而產生的噪聲，亦為旋轉噪聲。氣流在蝸殼中的擴壓脈動脫離，葉片進口處流動分離及偏離最佳工況點的流動惡化，亦為旋轉噪聲。,26,風扇噪聲（三）,旋渦噪聲產生的機理,：紊流邊界層及脫離引起氣流壓力脈動造成的，邊界層脫離和紊流脈動彈性較大，頻率較寬，也稱寬頻噪聲,27,風扇壽命,At 40,ambient,Bearing type,Cost,保證,life(hr),製程難度,Noise,水平,Ball Bearing,A,70,000,易,普通,One Ball One sleeve,2/3A,40,000,難,普通,Sleeve,1/8A,30,000,易,佳,Hydraulic,1/2A,50,000,易,佳,28,可靠性,_,高溫高濕,高溫高濕測試,測試溫度,60,2,，,相對溼度,95,，,放置,96,小時後,、,放置於室溫下,12,小時後,，,測試性能,。,運轉電壓為承認書中的,MAX,值。,【,分為“放置”及“運轉”測試,】,IEC Pub.68-2-3,CNS,3623,（C 6010）,各,3,29,可靠性,_,耐熱性,耐熱性,環境溫度,85,2,，,放置,96,小時後,、,放置於室溫下,12,小時後,，,測試性能,。,運轉電壓為承認書中的,MAX,值。,【,分為“放置”及“運轉”測試,】,IEC.Pub.68-2-2.,CNS 3634,（C 6021）,各,3,30,可靠性,_,耐冷性,耐冷性,環境溫度,-40,2,，,放置,96,小時後,、,放置於室溫下,12,小時後,，,測試性能,。,運轉電壓為承認書中的,MAX,值。,【,分為“放置”及“運轉”測試,】,IEC.Pub.68-2-1.,CNS 11233,（C 6242）,各,3,31,可靠性,_,冷熱溫度沖擊,冷熱溫度衝擊,放置測試：,高溫設定,85,2,、低溫設定,-40,2,測試,cycle,：,50,回,放置於室溫下,12,小時後,，,測試性能,。,IEC.Pub.68-2-14.,CNS 3633,（C 6020）,6,32,可靠性,_,鎖固測試,鎖固測試,規格電壓鎖固,72,小時後性能測試。,6,風扇正常運轉,33,可靠性,_,死角測試,死角測試,規格電壓,ON,：,1/s OFF,：,5/s,測試,cycle,：,1000,回,6,風扇正常運轉,34,可靠性,_,振動測試,震動測試,.,測試設定為,位移量,0.75mm,頻率範圍,1.,10Hz55Hz/30,秒,2.,55 Hz 10Hz/30,秒,線性掃描,60,回,CNS 5076,(C6051),5,35,可靠性,_,落下測試,落下測試,測試距離：,100cm,單體、三面各一個方向自由落下。,IEC.Pub.68-2-32.,CNS 13215,（C 6354）,5,36,37,