选择一排风机房进行消声设计计算，现选择SEF/EAF-AB1-7、SEF/EAF-AB1-8排风机房作消声设计计算。

该系统由2台65000/21667CMH，余压400Pa/200Pa的轴流排风机组合成一系统，分两支管，每支管共14个进风口支风管截面为1600*450，进风口800*600的6个，1000*200的8个。

选择一离机房最近的进风口进行计算，并把各节点编号，如附图，假设节点⑩正下方1.5m处，在平时排风状态下，要求由于排风系统造成的噪声不超过NR40曲线或A声级45dB(A)。

平时排风状态时，支管排风总风量为21667CMH，节点⑩的排风量为921CMH，其方法及计算结果如下表：合计NR曲线631252505001000200040008000Lw（A）(dB) 1①单台轴流风机噪声（节点①的噪声）979590858176696281.0762②节点②的噪声（2台轴流风机噪声叠加）（即静压箱入口噪声）1009691878480726589.0843消声静压箱规格4000*1600*10004消声器的吸声系数α0.10.250.4 1.2 1.2 1.2 1.3 1.45消声器的消声量 L=1.6*α*P*L/S0.280.7 1.12 3.36 3.36 3.36 3.64 3.926③节点③的噪声99.795.389.983.680.676.668.461.186.081 7阀门的气流噪声衰减133543538④节点④的噪声10198.392.988.684.679.673.464.190.085 9消声器规格为1600*450*160010消声器的吸声系数α0.10.250.4 1.2 1.2 1.2 1.3 1.411消声器的消声量 L=1.6*α*P*L/S 2.16 5.48.6515.615.614.314.112.112⑤节点⑤的噪声98.692.984.273.169.165.459.35274.06913⑤-⑥的通风截面积1600*450，风量21667CMH，管道流速8.4s/m，直流管道的气流噪声较大，其直管内的噪声衰减可忽略不918377737067656414⑥节点⑥的噪声98.692.984.273.169.165.459.35215无衬里的弯头噪声衰减1335435316⑦节点⑦的噪声97.689.981.268.165.162.4575570.06517⑧-⑦的通风截面积1600*450，风量21667CMH，管道流速8.4s/m，直流管道的气流噪声较大，其直管内的噪声衰减可忽略不计18⑧节点⑧的噪声97.689.981.268.165.162.4575570.065 19无衬里的弯头噪声衰减3545332120⑨节点⑨的噪声83746863.162.159.4555467.06221⑩-⑨的通风截面积1600*450，风量21667CMH，管道流速8.4s/m，直流管道的气流噪声较大，其直管内的噪声衰减可忽略不计22⑩节点⑩的噪声83746863.162.159.4555467.062 23节点⑩的出风口自然衰减噪声 4.2 4.2 4.2 4.2 4.2 4.2 4.2 4.224出风口处噪声78.869.863.858.957.955.250.849.863.05825出风口处正下方1.5m处噪声，因此处有两个出风口，噪声会叠加，故噪声为81.872.866.861.960.958.253.852.866.061送风系统消声设计计算（1）备注倍频带中心频率（Hz）序号节点编号计算方法与步骤增加消声器后的计算结果如下表：合计NR曲线631252505001000200040008000Lw（A）(dB) 1①单台轴流风机噪声（节点①的噪声）979590858176696281.0762②节点②的噪声（2台轴流风机噪声叠加）（即静压箱入口噪声）1009691878480726589.0843消声静压箱规格4000*1600*10004消声器的吸声系数α0.10.250.4 1.2 1.2 1.2 1.3 1.45消声器的消声量 L=1.6*α*P*L/S0.280.7 1.12 3.36 3.36 3.36 3.64 3.926③节点③的噪声99.795.389.983.680.676.668.461.185.681 7阀门的气流噪声衰减133543538④节点④的噪声10198.392.988.684.679.673.464.189.685 9消声器规格为1600*450*160010消声器的吸声系数α0.10.250.4 1.2 1.2 1.2 1.3 1.411消声器的消声量 L=1.6*α*P*L/S 2.16 5.48.6515.615.614.314.112.112⑤节点⑤的噪声98.692.984.273.169.165.459.35274.169消声器规格为1600*450*1600消声器的吸声系数α0.10.250.4 1.2 1.2 1.2 1.3 1.413消声器的消声量 L=1.6*α*P*L/S 2.16 5.48.6515.615.614.314.112.114⑥节点⑥的噪声96.487.575.657.553.551.145.339.958.554 15无衬里的弯头噪声衰减1335435316⑦节点⑦的噪声95.484.572.652.549.548.1575554.55017⑧-⑦的通风截面积1600*450，风量21667CMH，管道流速8.4s/m，直流管道的气流噪声较大，其直管内的噪声衰减可忽略不计18⑧节点⑧的噪声95.484.572.652.549.548.1575554.550 19无衬里的弯头噪声衰减3545332120⑨节点⑨的噪声83746847.546.545.1555451.54721⑩-⑨的通风截面积1600*450，风量21667CMH，管道流速8.4s/m，直流管道的气流噪声较大，其直管内的噪声衰减可忽略不计22⑩节点⑩的噪声83746847.546.545.1555451.547 23节点⑩的出风口自然衰减噪声 4.2 4.2 4.2 4.2 4.2 4.2 4.2 4.224出风口处噪声78.869.863.843.342.340.950.849.847.34225出风口处正下方1.5m处噪声，因此处有两个出风口，噪声会叠加，故噪声为81.872.866.846.345.343.953.852.850.345说明：从计算结果看，系统设计基本能满足噪声要求。

送风系统消声设计计算（2）备注倍频带中心频率（Hz）序号节点编号计算方法与步骤LwA - A weighted sound power level, based on ANSI S1.4. dBA - A weighted sound pressure level, based on 11.5 dB attenuation per octave band at 1.5 m. Noise Criteria (NC) based on an average attenuation of 11.5 dB per octave band at 1.5 m.3S t a t i c P r e s s u r e (P a ) x 10002468101214B r a k e P o w e r (k W )02468101214Volume (m3/h) x 1,00005101520253035401411R PMS ys t e mRPM Curve System Curve Brake Power Curve Do not select to the left of this surge curve TBI-FS Medium Pressure AxialStandard Construction FeaturesHOUSING: Continuously welded housing • Inlet and Outlet flanges with mounting holes •Adjustable motor base • Extended lube lines with grease fittings BEARINGS, SHAFT AND PROPELLER: Heavy duty, self aligning pillow block bearings •Turned, precision ground and polished shaft • Airfoil blade design • Welded steel propeller895924 9651,007AIRFLOW 864 14 DIA QTY 8 MAX 775572683 14 DIAOPTIONAL UNIVERSAL MOUNTING BRACKETS INCLUDED NOTES: All dimensions shown are in units of millimetersSELECTED OPTIONS & ACCESSORIESUniversal Mounting Brackets Motor Cover Permatector Coating on Steel Components Class F Motor Insulation Drive Service Factor of 1.5 - Standard HT-Option II (538º C/ 15 min, 400º C/ 2hr, 260º C/ 4hr)9.2/2.2KW 4/8P 2-Speed Motor TAGSSAF-AB1-1SAF-AB1-2SAF-AB1-3SAF-AB1-4Centrifugal Product Type: SAF-AB1-1, 2, 3, 4Mark:LwA - A weighted sound power level, based on ANSI S1.4. dBA - A weighted sound pressure level, based on 11.5 dB attenuation per octave band at 1.5 m. Noise Criteria (NC) based on an average attenuation of 11.5 dB per octave band at 1.5 m.3S t a t i c P r e s s u r e (P a ) x 100012345B r a k e P o w e r (k W )0.00.51.01.52.02.5Volume (m3/h) x 1,0000510152025828R PM S y s te m RPM Curve System Curve Brake Power Curve Do not select to the left of this surge curve TBI-FS Medium Pressure AxialStandard Construction FeaturesHOUSING: Continuously welded housing • Inlet and Outlet flanges with mounting holes •Adjustable motor base • Extended lube lines with grease fittings BEARINGS, SHAFT AND PROPELLER: Heavy duty, self aligning pillow block bearings •Turned, precision ground and polished shaft • Airfoil blade design • Welded steel propeller895924 9651,007AIRFLOW 864 14 DIA QTY 8 MAX 775572683 14 DIAOPTIONAL UNIVERSAL MOUNTING BRACKETS INCLUDED NOTES: All dimensions shown are in units of millimetersSELECTED OPTIONS & ACCESSORIESUniversal Mounting Brackets Motor Cover Permatector Coating on Steel Components Class F Motor Insulation Drive Service Factor of 1.5 - Standard HT-Option II (538º C/ 15 min, 400º C/ 2hr, 260º C/ 4hr)9.2/2.2KW 4/8P 2-Speed Motor TAGSSAF-AB1-1SAF-AB1-2SAF-AB1-3SAF-AB1-4Centrifugal Product Type: Low Sp SAF-AB1-1, 2, 3, 4Mark:。