Chap1 open channel flow

3,209 views

Published on

Uniform Flow in Open Channel

Published in: Education
0 Comments
3 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
3,209
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
194
Comments
0
Likes
3
Embeds 0
No embeds

No notes for slide

Chap1 open channel flow

  1. 1. HYDRAULICS UNIFORM FLOW IN OPEN CHANNELS By Erni Syuhada Bt Mazwil Ishan
  2. 2. HYDRAULICS ENGINEERING • A scientific fluid flow particularly in water thoroughly in pipe, open channel, orifice and embankment, including the problem related to energy and pressure. • Related to water or fluid in dynamic condition.
  3. 3. CONTENT  What is Open Channel  Types of Open Channel Types of flowing water and control Solution of uniform flow in Open Channel
  4. 4. OPEN CHANNEL An open channel : a)The stream not completely enclosed by solid boundaries b)It has free surface subjected only to atmospheric pressure. c)Referred as free-surface flow or gravity flow
  5. 5. Open Channel TYPES OF OPEN CHANNEL Natural Channel Irregular shape i.e : river, hillsides rivulets, tidal etuaries Artificial Channel Regular shape i.e : drains, culverts, sewer, tunnels
  6. 6. TYPES OF OPEN CHANNEL
  7. 7. TYPES OF FLOWING WATER AND ITS CONTROL Rapidly Varied Flow i.e : hydraulic jump Non-Uniform Flow ≠ 0 Uniform Flow = 0 Gradually Varied flow i.e : upstream of obstruction Open Channel Steady Flow = 0 Open Channel Unsteady Flow ≠ 0
  8. 8. TYPES OF FLOWING WATER AND ITS CONTROL Steady • y (depth of water) and v (velocity) remain constant with respect to time Unsteady Flow • y and v change with time
  9. 9. TYPES OF FLOWING WATER AND ITS CONTROL Uniform • y (depth of water) and v (velocity) remain constant along the channel. Figure 2.0 Non - uniform Flow • y and v change along the length of the channel Figure 2.0
  10. 10. • Flow Classifications 1) Depending on the Reynolds number, Re – Laminar Flow (if Re < 500): very slow and shallow flowing water in very smooth open channels. – Turbulent Flow (if Re > 1000): ordinary flow in ordinary open channels. – Transition Flow (if 500 < Re < 1000) TYPES OF FLOWING WATER AND ITS CONTROL V = average channel velocity L = length of channel v = kinematic viscosity of fluid
  11. 11. 2) Depending on Froude number, Fr – Fr = 1 : Critical Flow – Fr < 1 : Subcritical Flow – slow flowing water – Fr > 1 : Supercritical Flow – fast flowing water TYPES OF FLOWING WATER AND ITS CONTROL V = average channel velocity g = gravity acceralation D = hydraulics water depth
  12. 12. TURBULENT LAMINAR
  13. 13. TYPES OF FLOWING WATER AND ITS CONTROL Critical Section (In uniform and non-uniform flow) 1) If So < Sc, y > yc : Subcritical flow 2) If So = Sc, y = yc : Critical flow 3) If So > Sc, y < yc : Supercritical flow Figure 3.0
  14. 14. Bernoulli’s Equation Lhz g Vp z g Vp +++=++ 2 2 22 1 2 11 22 γγ
  15. 15. Open Channel GEOMETRIC PROPERTIES OF OPEN CHANNELS RECTANGULAR CHANNEL TRAPEZOIDAL CHANNEL
  16. 16. • The terminology of geometric elements y : depth of flow T : top width b : bottom channel width m : side slope So : channel bottom slope v : average flow density Fr : Froude number Re : Reynold number L : length of channel Q : flow rates , Q = AV A : area of the flow P : wetted perimeter R: hydraulic radius at cross section D : hydraulics water depth V : volume ν : velocity E : specific energy ∆z : weir height θ : flow temperature q = discharge over width (m) GEOMETRIC PROPERTIES OF OPEN CHANNELS
  17. 17. Type of channel TOP WIDTH, T AREA, A WETTED PERIMETER, P RECTANGULAR B By B + 2y TRAPEZOIDAL B+2my By + my2 B+2y √ 1+m2 GEOMETRIC PROPERTIES OF OPEN CHANNELS Where,
  18. 18. UNIFORM FLOW IN OPEN CHANNEL Uniform flow is an equilibrium condition that flow tends to if the channel : a)constant slope b)constant cross section c)constant roughness d)depth, water area, velocity and discharge at every section of channel are constant e)channel bed, water surface and energy line are parallel, So = Sw = S f)y1 = y2 , V1 = V2
  19. 19. • CHEZY FORMULA : UNIFORM FLOW IN OPEN CHANNEL Where ; V = mean velocity (m/s) C = Chezy’s factor of flow resistance (m1/2 /s) R = hydraulic radius So = slope of energy line Q = Discharge (m3 /s) • MANNING FORMULA : Where ; V = mean velocity (m/s) n = Manning’s coefficient of roughness (s/m1/3 ) R = hydraulic radius So = slope of energy line Q = Discharge (m3 /s)
  20. 20. UNIFORM FLOW IN OPEN CHANNEL Closed conduits flowing partly full Corrugated metal storm drains 0.010 Concrete culvert 0.024 Unfinished concrete 0.013 Clay drain tile 0.014 Lined or built up channels Unpainted steel 0.012 Planed wood 0.012 Unplaned wood 0.013 Trowel – finished concrete 0.013 Rough concrete 0.017 Glazed brick 0.020 Brick in cement mortar 0.013 Excavated channels Clean earth (straight channel) 0.022 Earth with weeds (winding channel) 0.030 Natural streams Clean and straight 0.030 Weedy reaches, deep pools 0.100 Typical values of Manning’s coefficient, n
  21. 21. SOLUTION IN OPEN CHANNEL • Conveyor Factor From eq We obtain ; For Chezy For Manning
  22. 22. • Section Factor, Z For Chezy ; For Manning; SOLUTION IN OPEN CHANNEL • Thus, normal depth, yo can be obtain by using trial and error method
  23. 23. SOLUTION IN OPEN CHANNEL • Example : Given trapezoidal channel 10m wide with side slope of 1:1.5. Bed slope is 0.0003. The channel with concrete lining, n = 0.012. Calculate the velocity, V and flow rate, Q when the flow depth is 3.0m. If the flow rate is 50m/s, determine the slope, So of channel.

×