Orifice

CIVE340 LAB – Experiment#1: Orifice Discharge 1 CIVE340 Fluid Mechanics Laboratory Experiment #1: Orifice Discharge Objective: Determine the discharge coefficient, C d , for an orifice at the bottom of a cylindrical tank based on an equation derived from the continuity equation. Equipment: 1) Hydraulic bench 2) Orifice Apparatus 3) 3 mm and 6 mm circular edged orifices 4) Stop watch Procedure: 1) Place the orifice apparatus on the hydrostatic bench, and attach the 3mm-diameter orifice plate. 2) Cover the orifice and fill the tank to above the 40 cm level. Keep the orifice covered. 3) Uncover the orifice to let the water discharge through the orifice. 4) Start timing once the water level reaches h=40 cm. Record the time at 2cm-increment levels down to level h=2 cm(i.e. h=38, 36, 34, .. 2 cm). Record time at 0.5 cm below h=2 cm down to h=0.5 cm (i.e. h= 1.5, 1.0 and 0.5 cm). Use the attached table to record the times. 5) Replace the 3mm –diameter orifice place with the 6mm – diameter and repeat steps 1-4. Results and Analysis: 1) Derive t as function of h for the upper and lower part of the cylinder. Your final answers should match the following formulas: a. Upper part: ( ) 2 1 2 1 0 2 2 2 h H D D g C t ORF CYN d Upper − ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ = b. Lower part: ( ) ( ) 2 1 2 1 2 4 2 1 0 h H D D d D g C t t b ORF CYN CYN d H H Lower b − Π − Π + = → 2) Use recorded data to plot t against h (one plot per each orifice diameter). For each plot determine the line slopes that correspond to the upper and lower sections of the cylinder. Calculate the discharge coefficient C d for each slope given that D CYN =13.7 cm, d = 6mm and g = 9.81 m/sec 2

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CIVE340 LAB – Experiment#1: Orifice Discharge

CIVE340 Fluid Mechanics Laboratory Experiment #1: Orifice Discharge

Objective: Determine the discharge coefficient, Cd, for an orifice at the bottom of a

cylindrical tank based on an equation derived from the continuity equation.

Equipment: 1) Hydraulic bench 2) Orifice Apparatus 3) 3 mm and 6 mm circular edged orifices 4) Stop watch

Procedure: 1) Place the orifice apparatus on the hydrostatic bench, and attach the 3mm-diameter orifice plate.

2) Cover the orifice and fill the tank to above the 40 cm level. Keep the orifice covered.

3) Uncover the orifice to let the water discharge through the orifice. 4) Start timing once the water level reaches h=40 cm. Record the time at

2cm-increment levels down to level h=2 cm(i.e. h=38, 36, 34, .. 2 cm). Record time at 0.5 cm below h=2 cm down to h=0.5 cm (i.e. h= 1.5, 1.0 and 0.5 cm). Use the attached table to record the times.

5) Replace the 3mm –diameter orifice place with the 6mm – diameter and repeat steps 1-4.

Results and Analysis:

1) Derive t as function of h for the upper and lower part of the cylinder. Your final answers should match the following formulas:

a. Upper part:

( )21210

22 hH

gCt

ORF

CYN

dUpper −⎟⎟

⎠

⎞⎜⎜⎝

⎛=

b. Lower part:

( ) ( )21212

hHD

DdDgC

tt bORF

CYNCYN

dHHLower b

−Π−Π

+= →

2) Use recorded data to plot t against h (one plot per each orifice diameter).

For each plot determine the line slopes that correspond to the upper and lower sections of the cylinder. Calculate the discharge coefficient Cd for each slope given that DCYN =13.7 cm, d = 6mm and g = 9.81 m/sec2