离心通风机的设计

1、离心通风机的设计已知条件：风机全压 Ptf =2554 Pa,风机流量qv=5700 m?/h,风机进口压力P.101324.72Pa风机进口温度tm=25 C空气气体常数R=287J/kg x k 风机转速 n=2900r/min.空气密度p760*133.32 kg 3 1.1847kg 3R273 tin 287 273 30.6 mm.风机的比转速ns5.54niF inns5.54 29005700、3600ns5.54niF inns5.54 29005700、36001.21.1847342554=55.73.选择叶片出口角2A2A = 35由于比转速较小，选择后弯圆弧叶片。.估

2、算全压系数tt 0.3835 2.7966 10 3 2A 1.439 10 5 n220.3835 2.7966 10 3 35 1.439 10 5 55.7322=0.873.估算叶轮外缘圆周速度u2PtF11.187 0.8732554ms70.277ms.估算叶轮外缘出口直径D2D260u2 D260u2 n60 70.277 m 3.1416 29000.462m选择 D2=0.46m,相应地 U2 69.85 m/.计算风机的t、Ds、PtF12PtF12一 U222554121.1847 69.8520.884qv5700/3600 TOC o 1-5 h z 0.136D2u

3、2 0.462 69.854411t40.884 4Ds 0.993/ 0.993 2.611s12.0.1361234 t11234 t10.136 20.884%0.4058确定叶轮进口直径D选择悬臂式叶轮，d=0,参考表3-11a选c0=30ms ;56700Do3600 m 0.259 Do304D0/D2 0.259/0.462 0.5606 符合表 3-11b 的 D0/D2范围。.叶片进口直径Di mD11.1D0(1.1 0.259)m 0.285D1d2 0.6169.选择径向进气190 , C1c1 r , C1c1r11选择叶片入口前进气速度Ci( m/s)由于风机的0.

4、1559 0.1，DiD0.6169查图，宜采用扩散形进口,2选用 C1 =0.538c0= 0.538 30 嗯 16.14 嗯,C1tan 1u ,C1tan 1u 116 . 14 0 .3730 0.2852900/ 601 = 20 2713确定叶片入口几何角1A/1A 11选冲角i/ 9 33/ ,则1a = 20 27+ 9 33/= 3014确定叶片入口宽度b1, _ qv5700/36000.110mb1 =丁0.110mD1c1r3.1416 0.285 16.14.选叶片数目Zsin 2Asin35Z 8.512A 8.512.731 J 1 0.6169D3如表3-7所

5、示，选用Z=13片.叶片进口阻塞系数1D1sin D1sin 1A13 0.0030.285 sin350.9129其中选用3mm优质薄板叶片(1 0.003m ).气流进入叶片后的径向分速5r和气流角i/ c1 c/ c1 c1rc11/c1tan 1U1必 m 17.6800.9129 s17.6800.285 2900/600.4085122 13i 3022 13 7 47.选择叶片出口后径向分速C2rms选择近似双曲线规律的圆弧前盖，故选用c2r C1r 16.14m s19确定叶片出口宽度b2b2b1b2b1D1D20.110 0.285m0.4620.072m取b2/D172/4

6、62 0.1558c2r . u2 16.14/70.277 0.2320.叶片出口阻塞系数2D2 sin 2A13 0.0030.462 sin 350.953221 .叶片出口前径向分速C2rC2rc2r 上 16.14/0.9532 16.9333222.无限叶片数气流出口圆周风速C2uc2u u2 c2r cot 2A 70.277 16.933 cot35 m s 46.094m s23。估算滑差系数1.5 1.1 2a/9013 1213 12D1d70.81182 0.86 0.8146.09470.2770.81182 0.86 0.8146.09470.2770.9141.5

7、 1.1 30/90131 0.61692.有限叶片数气流出口圆周分速 c2uc2u Kc2u 0.8118 46.094 m s 37.419m s.校核全压系数tc?u2 hK上u2参考表3-9tFin 0.82；h 0.86它说明本风机原选用t 0.873有余量，其误差为0.915 0.8730.873100%4.70%26.叶轮出口前、后的气流速度c2,W29,W2和角度出口前aJcL c2r 37.4 1 9 (0.231 cos35 0.1425 cos30 ) 1 6.9332 m 41.072 (0.231 cos35 0.1425 cos30 )tan 222 %C2utan

8、 222 %C2uC2r7 70.2772 37.419216.9332 %36.965 msC2rC2u16.93337.4190.4525224 21出口后C2 启CT J37.4192 16.142 % 40.751ms2 J u2 c2u 2 c2r7 70.2772 37.419216.142 嗯 36.608 嗯tan 2C2r16.14tan 2C2r16.1437.4190.431223 2027.校核1. 21u；17.680202852900/60 %46.748ms46.74836.9651.2646.74836.9651.26.确定叶片圆弧半径Rk和中心圆半径R0(0.

9、461/2)2 (0.285/2)2m 0.251m2(r2 cos 2A r(0.461/2)2 (0.285/2)2m 0.251mR0Rk2 2Rk2 cos 2 A.0.2512 0.2312 2 0.251 0.231 cos35 m=0.146m.选择蜗壳宽度B根据前述，得Bn- (0 - 0.06) D2112.555.73B (0 - 0.06)0.462m 0.229 - 0.257m112.5取 B=0.25m.采用平均速度Cm计算涡壳型线，选Cm (0.65 0.75)C2u=(0.650.75) 37.419=24.322-28.064取Cm=26m s.确定蜗壳张开度

10、A(m)Aqv5700/3600A - 0.2436mBCm0.25 2632确定蜗壳绘制半径采用不等距基元，且a=0.15A=0.0365mb=0.1333A=0.0325mc=0.1167A=0.0284md=0.1A=0.02436mRa R2 A a 0.231 0.2436 0.0365 0.4381m66RR26Ab 0.231 688466RR26Ab 0.231 6884RcR2-A c 0.2318RdR22Ad 0.2312 833.蜗壳出口长度C取 Fc/Fk(C B)/(A B)故 C=1.4A=1.4*/b 0.2436=0.3410.2436 0.0325 0.38121m40.2436 0.0284 0.3244m82 0.2436 0.02436 0.2675m81.4蜗壳出口速度CcqvCB5700/36000.341 0.2518.573 m s蜗舌间隙t和蜗舌顶端圆半径r