BRAE236 Open Channel Q

BRAE236 Open Channel Q - Standard Flow Measurement Devices...

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1 Standard Flow Measurement Devices ITRC Cal Poly Flumes, Weirs, Propeller Meters Critical Flow Devices For one depth, there is one ITRC Cal Poly corresponding flow rate
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2 Weirs ITRC Cal Poly 90° H 1 4 H L H L TRIANGULAR (90° V-NOTCH) TRAPEZOIDAL (CIPOLLETTI) RECTANGULAR ITRC Cal Poly Types of Weirs
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3 ITRC Cal Poly Cipolletti Weir Ci ll tti W i ITRC Cal Poly Cipolletti Weir
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4 ITRC Cal Poly Rectangular Weir Staff Gauge Head ITRC Cal Poly
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5 Y1 Y2 Headloss = Y2 - Y1 Flume Head Weir Headloss Weir Crest Note: Air pocket behind crest Free Flow Weir C ITRC Cal Poly Crest Note: Downstream water level above crest Submerged
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6 Upstream Head Downstream Head ITRC Cal Poly 90 deg. weir angle Submergence Submergence = Downstream head Upstream head ITRC Cal Poly
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7 Submergence Multiply Uncorrected Flow Rate By: 01 . 0 0 Weir Adjustment for Submergence 0.1 0.99 0.2 0.96 0.3 0.93 0.4 0.89 0.5 0.84 0.6 0.78 0.7 0.70 ITRC Cal Poly 0.8 0.59 0.9 0.44 0.14 Weirs Biggest Problem: Velocity of Approach ITRC Cal Poly
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8 Depth due to surge (or "run up" on the weir rule) Equivalent depth of upstream staff gage Velocity Head Depth at curvature of the nappe ITRC Cal Poly Weirs Suppressed Versus Contracted ITRC Cal Poly
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9 Weirs Suppressed Plan View (from above) CFS = 3.33 L H 1.5 ITRC Cal Poly Contracted CFS = 3.33 (L-.2H) H 1.5 (note: The 3.33 assumes a sharp crested weir) Contracted or Suppressed??? ITRC Cal Poly
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10 Suppressed !!!!! ITRC Cal Poly Contracted Weir, V= 0 Discharge equation: Q = 3.33 (L - 0.2H)(H^1.5) Q is CFS L is feet of crest length H is feet of head Flow rates below are in CFS UNSUBMERGED VELOCITY OF APPROACH = 0.0 Crest Length, Feet HEAD, ft. 1 2 3 4 5 6 8 10 0.1 0.1 0.2 0.3 0.4 0.5 0.6 0.8 1.1 0.2 0.3 0.6 0.9 1.2 1.5 1.8 2.4 3.0 0.3 0.5 1.1 1.6 2.2 2.7 3.3 4.3 5.4 0.4 0.8 1.6 2.5 3.3 4.1 5.0 6.7 8.4 0.5 1.1 2.2 3.4 4.6 5.8 6.9 9.3 11.7 0.6 1.4 2.9 4.5 6.0 7.6 9.1 12.2 15.3 0.7 1.7 3.6 5.6 7.5 9.5 11.4 15.3 19.2 0.8 2.0 4.4 6.8 9.1 11.5 13.9 18.7 23.4 0.9 2.3 5.2 8.0 10.9 13.7 16.5 22.2 27.9 1.0 2.7 6.0 9.3 12.7 16.0 19.3 26.0 32.6 1.1 3.0 6.8 10.7 14.5 18.4 22.2 29.9 37.6 1.2 3.3 7.7 12.1 16.5 20.8 25.2 34.0 42.7 1.3 3.7 8.6 13.5 18.5 23.4 28.3 38.2 48.1 1.4 4.0 9.5 15.0 20.5 26.0 31.6 42.6 53.6 1.5 4.3 10.4 16.5 22.6 28.8 34.9 47.1 59.3 16 46 11 3 18 1 24 8 31 5 38 3 51 8 65 2 ITRC Cal Poly 1.6 4.6 11.3 18.1 24.8 31.5 38.3 51.8 65.2 1.7 4.9 12.3 19.6 27.0 34.4 41.8 56.5 71.3 1.8 5.1 13.2 21.2 29.3 37.3 45.4 61.4 77.5 1.9 5.4 14.1 22.8 31.6 40.3 49.0 66.5 83.9 2.0 5.7 15.1 24.5 33.9 43.3 52.7 71.6 90.4 2.1 5.9 16.0 26.1 36.3 46.4 56.5 76.8 97.1 2.2 6.1 17.0 27.8 38.7 49.5 60.4 82.1 103.9 2.3 6.3 17.9 29.5 41.1 52.7 64.3 87.6 110.8 2.4 6.4 18.8 31.2 43.6 56.0 68.3 93.1 117.9 2.5 6.6 19.7 32.9 46.1 59.2 72.4 98.7 125.0 2.6 6.7 20.7 34.6 48.6 62.5 76.5 104.4 132.3 2.7 6.8 21.6 36.3 51.1 65.9 80.7 110.2 139.8 2.8 6.9 22.5 38.1 53.7 69.3 84.9 116.1 147.3 2.9 6.9 23.4 39.8 56.2 72.7 89.1 122.0 154.9 3.0 6.9 24.2 41.5 58.8 76.1 93.4 128.0 162.6 3.1 6.9 25.1 43.3 61.4 79.6 97.8 134.1 170.5
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11 Contracted Weir, V= 3 Discharge equation: Q = 3.33 (L - 0.2H)((H+h)^1.5 - h^1.5) Q is CFS L is feet of crest length H is feet of head h is the velocity head, in feet The velocity is the velocity at the point the head is measured, upstream of the weir (feet/sec) Flow Rates Below are CFS UNSUBMERGED WEIR VELOCITY OF APPROACH = 3.0 FEET PER SECOND Crest Length Feet Crest Length, Feet HEAD, ft. 1 2 3 4 5 6 8 10 0.1 0.2 0.4 0.6 0.9 1.1 1.3 1.7 2.2 0.2 0.5 1.0 1.4 1.9 2.4 2.9 3.9 4.8 0.3 0.7 1.5 2.3 3.1 3.9 4.7 6.3 7.9 0.4 1.1 2.2 3.3 4.5 5.6 6.8 9.1 11.4 0.5 1.4 2.9 4.4 6.0 7.5 9.0 12.1 15.2 0.6 1.7 3.7 5.6 7.5 9.5 11.4 15.3 19.2 0.7 2.1 4.4 6.8 9.2 11.6 14.0 18.8 23.6 0.8 2.4 5.3 8.1 11.0 13.8 16.7 22.4 28.1 0.9 2.8 6.1 9.5 12.8 16.2 19.5 26.3 33.0 1.0 3.1 7.0 10.9 14.7 18.6 22.5 30.3 38.0 1.1 3.5 7.9 12.3 16.7 21.1 25.6 34.4 43.3 1.2 3.8 8.8 13.8 18.8 23.8 28.7 38.7 48.7 1.3 4.1 9.7 15.3 20.9 26.4 32.0 43.2 54.3 1.4 4.5 10.6 16.8 23.0 29.2 35.4 47.8 60.2 1.5 4.8 11.6 18.4 25.2 32.1 38.9 52.5 66.1 ITRC
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This note was uploaded on 01/13/2011 for the course BRAE 236 taught by Professor Styles during the Fall '08 term at Cal Poly.

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BRAE236 Open Channel Q - Standard Flow Measurement Devices...

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