BASIC HYDRAULIC PRINCIPLES OF OPEN-CHANNEL FLOW

BASIC HYDRAULIC PRINCIPLES

OF OPEN-CHANNEL FLOW

By Harvey E. Jobson and David C. Froehlich

U.S. GEOLOGICAL SURVEY

Open-File

Report

88-707

Reston, Virginia

1988

DEPARTMENT OF THE INTERIOR

DONALD PAUL HODEL, Secretary

U.S. GEOLOGICAL SURVEY

Dallas L. Peck, Director

For additional information

write to:

Copies of this report can be

purchased from:

Chief, Office of Surface Water

U.S. Geological Survey

415 National Center

12201 Sunrise Valley Drive

Reston, Virginia 22092

U.S. Geological Survey, Books

and Open-File Reports

Box 25425, Federal Center

Denver, Colorado 80225

CONTENTS

Page

Abstract ................................................................

Introduction ............................................................

Part I - Basic principles of hydraulics for an ideal fluid ..............

Lesson 1 - Fluid properties .......................................

Lesson 2 - Forces on submerged objects ............................

Lesson 3 - Similitude and dimensional analysis ....................

Lesson 4 - The energy equation for an ideal fluid .................

Part II - Steady uniform flow of real fluids in open channels ...........

Lesson 5 - Velocity profiles ......................................

Lesson 6 - The energy equation applied to real fluids .............

Lesson 7 - Flow resistance ........................................

Lesson 8 - Computations for steady, uniform flow ..................

Part III - Advanced principles of steady flow ...........................

Lesson 9 - Flow in channel sections with variable roughness .......

Lesson 10 - The momentum principle ................................

Lesson 11 - Specific energy .......................................

Part IV - Gradually varied flow in open channels ........................

Lesson 12 - Determination of flow resistance in open channels .....

Lesson 13 - Classification of water-surface profiles ..............

Lesson 14* - Local energy losses in natural channels ...............

Lesson 15 - Water-surface profile computations ....................

Part V - Discharge computations for rapidly varied flow .................

Lesson 16 - Rapidly varied flow at constrictions ..................

Lesson 17 - Flow through culverts .................................

Lesson 18 - Flow over weirs .......................................

References ..............................................................

Answers to problems .....................................................

1

1

2

2

8

17

27

34

34

43

51

58

61

61

66

71

79

79

97

104

107

116

116

124

132

145

147

ILLUSTRATIONS

Page

Figure 1-1.

2-1.

2-2.

2-3.

3-1.

4-1.

4-2.

4-3.

5-1.

5-2.

Free body diagram of fluid element .........................

Definition sketch of the pressure prism for vertical

rectangular gate .........................................

Definition sketch of the pressure prism for a submerged

gate 4 feet wide .........................................

Definition sketch of the pressure prism to compute the

total force of the water on a 4-foot wide gate ...........

Diagram illustrating flow through constriction, model, and

prototype ................................................

Definition sketch of steady flow through a streamtube ......

Definition sketch for the flow of an ideal fluid in an open

channel ..................................................

Definition sketch for the example problem of flow down a

ramp .....................................................

Definition sketch for sheet flow over a wide inclined plane

of width W ...............................................

Diagram illustrating velocity distribution in a fully

developed, rough turbulent flow ..........................

111

3

8

9

10

17

28

28

30

35

38

ILLUSTRATIONS

Page

Figure 6-1.

6-2.

7-1.

9-1.

10-1.

11-1.

11-2.

11-3.

12-1.

12-2.

12-3.

13-1.

13-2.

14-1.

15-1.

15-2.

16-1.

16-2.

16-3.

17-1.

17-2.

17-3.

18-1.

18-2.

18-3.

18-4.

18-5.

18-6.

Definition sketch of the energy diagram for open-channel

flow .....................................................

Diagram illustrating typical flow through a bridge

constriction .............................................

Diagram illustrating flow in a prismatic open channel ......

Definition sketch for cross section with overbank flow .....

Diagram illustrating the control volume for applying the

conservation of momentum equation for the flow past a

pier .....................................................

Definition sketch for the specific energy curve ............

Diagram illustrating flow changes from subcritical to

supercritical ............................................

Diagram illustrating critical flow at the outlet of a box

culvert ..................................................

Diagram illustrating eight types of roughness found in

sand-bed channels ........................................

Diagram illustrating the effect of size of bed material

and Froude number on the bed form and Manning's n for

a range of flow conditions with sands of 0.28- and

0.45-millimeter median diameter in an 8-foot wide

flume ....................................................

Graph showing the relation of stream power and median

grain size to the bed form ...............................

Sketch illustrating gradually varied flow in an open

channel longitudinal scale greatly reduced ..............

Definition sketch of surface profiles of varied flow .......

Sketch illustrating the energy grade lines at a local

obstruction ..............................................

Definition sketch for water-surface profile computation ....

Graph showing the variation of friction slope with

distance along the channel ...............................

Sketch illustrating the theoretical water-surface and

energy profiles through a contracted opening .............

Sketch illustrating the streamlines for flow through a

sharp-edged opening ......................................

Graph showing the coefficients for type 1 opening,

vertical embankments, and vertical abutments .............

Definition sketch of culvert flow ..........................

Diagram illustrating the classification of culvert flow ....

Graph showing the base coefficient of discharge for

types I, 2, and 3 flow in box culverts with square

entrance mounted flush in vertical headwall ..............

Definition sketch for a contracted, sharp-crested weir .....

Definition sketch for a broad-crested weir .................

Graph showing the coefficients of discharge for full

width, broad-crested weirs with downstream slope = 1:1,

and various upstream slopes ..............................

Definition sketch of a V-notch (triangular) sharp-crested

weir .....................................................

Definition sketch of a Cippoletti (trapezoidal)

sharp-crested weir .......................................

Diagram illustrating various other sharp-crested weir

profiles .................................................

IV

43

45

51

61

67

71

73

74

93

94

95

97

99

104

108

109

116

119

121

124

125

127

132

132

134

137

139

139

TABLES

Page

Table 1-1.

6-1.

Mechanical properties of some fluids ........................

Kinetic energy correction coefficients for natural

channels ..................................................

Values of the Manning resistance coefficient ................

Equations for resistance based on bed-material size .........

44

86

91

12-3.

Sediment grade scale ........................................

92

15-1.

15-2.

17-1.

Criteria used to select friction slope equation ............. 110

Computation sheet for backwater analysis .................... 112

Discharge coefficients for box or pipe culverts set

flush in a vertical headwall; types 4 and 6 flow .......... 129

12-1.

12-2.

4

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download