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Resistance coefficients for thin-walled perforated sheet or grid of
strips with sharp edged orifices (according to Fried & Idelchik).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Conditions:

 

     Range of sheet length to hole diameter ratio, 0 < l/Dh < 0.015

     Reynolds number, Re > 105

 

Where:

    

 

   for is the area of one orifice.

 

The resistance coefficient is given by:

 

 

 

 

 

Open Area

Resistance Coefficient

Open Area

Resistance Coefficient

0.01

28677.936

0.51

3.729

0.02

7055.112

0.52

3.478

0.03

3085.115

0.53

3.245

0.04

1707.168

0.54

3.027

0.05

1074.657

0.55

2.824

0.06

733.924

0.56

2.635

0.07

530.188

0.57

2.458

0.08

399.066

0.58

2.293

0.09

309.930

0.59

2.138

0.10

246.716

0.60

1.993

0.11

200.347

0.61

1.858

0.12

165.385

0.62

1.731

0.13

138.414

0.63

1.613

0.14

117.203

0.64

1.501

0.15

100.243

0.65

1.397

0.16

86.487

0.66

1.299

0.17

75.190

0.67

1.207

0.18

65.810

0.68

1.121

0.19

57.944

0.69

1.040

0.20

51.291

0.70

0.964

0.21

45.620

0.71

0.892

0.22

40.751

0.72

0.825

0.23

36.544

0.73

0.762

0.24

32.888

0.74

0.703

0.25

29.693

0.75

0.647

0.26

26.888

0.76

0.595

0.27

24.413

0.77

0.546

0.28

22.221

0.78

0.500

0.29

20.273

0.79

0.457

0.30

18.534

0.80

0.416

0.31

16.976

0.81

0.378

0.32

15.578

0.82

0.343

0.33

14.318

0.83

0.309

0.34

13.181

0.84

0.278

0.35

12.150

0.85

0.249

0.36

11.215

0.86

0.221

0.37

10.364

0.87

0.196

0.38

9.589

0.88

0.172

0.39

8.880

0.89

0.150

0.40

8.232

0.90

0.129

0.41

7.637

0.91

0.110

0.42

7.091

0.92

0.093

0.43

6.589

0.93

0.076

0.44

6.126

0.94

0.062

0.45

5.700

0.95

0.048

0.46

5.305

0.96

0.036

0.47

4.941

0.97

0.025

0.48

4.603

0.98

0.015

0.49

4.290

0.99

0.007

0.50

3.999

1.00

0.000

REFERENCE:

Fried & Idelchik, Flow Resistance: A Design Guide for Engineers; Hemisphere Publishing Corporation, 1989; Diagram 8.1

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