离心通风机的设计

离心通风机的设计

已知条件：风机全压P tf =2554 Pa,风机流量q v =5700 m 3/h, 风机进口压力P in =101324.72Pa 风机进口温度t m =25°C 空气气体常数R=287J/㎏×k 风机转速n=2900r/min

1.空气密度ρ

()()33in 1847.16.3027328732.133*760273m kg m

kg t R P in =⎥⎦⎤⎢⎣⎡+=+=

ρ

2.风机的比转速

4

32.154.5⎪⎪⎭

⎫ ⎝⎛=iF in v

s q n

n ρρ

4

325541847.12.13600

5700

290054.5⎪⎭

⎫

⎝⎛⨯⨯

⨯=s n =55.73

3．选择叶片出口角A 2β

A 2β=︒35

由于比转速较小，选择后弯圆弧叶片。 4．估算全压系数t ψ

[]210439.1107966.23835.02523⨯⨯-⨯+=--s A t n βψ

[]273.5510439.135107966.23835.0253⨯⨯⨯-⨯⨯+=-- =0.873

5．估算叶轮外缘圆周速度2u

s

m s m p u t tF 772.70873.0187.12

1

25542

12=⨯⨯=

=

ρψ 6. 估算叶轮外缘出口直径2D

m m n u D 462.02900

1416.377

2.70606022=⎪⎭

⎫

⎝⎛⨯⨯==

π 选择2D =0.46m ，相应地s m 85.692=u 7. 计算风机的t ψ、ϕ、s D 、σ

884.085.691847.12

1

2554u 2

1p 222tF t =⨯⨯=

=

ρψ

136

.085

.6946.04

5700/3600

u D 4

q 2

2

22

v

=⨯⨯=

=

π

π

ϕ

611.20.136

884

.0993.0993

.04

12

1

4

1t s =⨯

==ϕ

ψD

405

.0884

.0136.04

3

214

3

t

21

==

=

ψϕ

σ

8.确定叶轮进口直径0D

⎪⎪⎪⎪⎭

⎫

⎝

⎛+=2

004d c q D v

π

选择悬臂式叶轮，d=0,参考表3-11a 选0c =30s m ；

259.0m 3043600567000=⎪⎪⎪⎪

⎭

⎫

⎝⎛⨯=πD m 5606.0462.0/259.020==D D 符合表3-11b 的20D D 范围。

9.叶片进口直径()m 1D

285.0m )259.01.1(1.101=⨯==D D 6169.02

1

=D D

10.选择径向进气

'1'1111,c 90r r c c c ==︒=，α

11.选择叶片入口前进气速度'1c （m/s ）

由于风机的1.01559.0>=ϕ ，6169.02

1

=D

D 查图，宜采用扩散形进口，即11>ξ

选用 '

1c =0.5380c =()s m 14.16s m 30538.0=⨯ 12.计算叶片入口前气流角‘1β

3730.060

/2900285.014.16u c tan 111

=⨯⨯==πβ’‘

‘1β='2720︒

13.确定叶片入口几何角A 1β

/'11i A +=ββ

选冲角//339︒=i ，则

A 1β='2720︒+/339︒=︒30

14.确定叶片入口宽度1b

1b =

m c D q r v 110.014.16285.01416.33600/5700/

11=⎪⎭

⎫

⎝⎛⨯⨯=π 15.选叶片数目Z

73.126169

.0135sin 5

.81sin 8.5

Z 3

1

2A

=-︒

=-=D

D β

如表3-7所示，选用Z=13片 16.叶片进口阻塞系数1τ

9129.035sin 285.0003

.0131sin 11111=︒

⨯⨯⨯-=-

=πβπδτA D Z

其中选用3mm 优质薄板叶片（()m 003.01=δ） 17.气流进入叶片后的径向分速r 1c 和气流角i

4085.060

/2900285.0680.17tan 680.179129.014.16c c c 1/111/1

1r 1=⨯⨯==

=⎪⎭

⎫ ⎝⎛===πβτu c s m

'

477'132230'

13221︒=︒-︒=︒=i β

18.选择叶片出口后径向分速()s m r 2'c 选择近似双曲线规律的圆弧前盖，故选用

s m c r 14.16''c 1r 2=≈

19.确定叶片出口宽度b 2

m m D D b b 072.0462.0285.0110.02112=⎪⎭

⎫

⎝⎛⨯==

取

23

.0277.70/14.161558.0462/72/2212====c D b r

20.叶片出口阻塞系数2τ

A

D Z 222

2sin 1βπδτ-

=

9532

.035sin 462.0003

.0131=︒

⨯⨯⨯-

=π