1. ENTC-303Dr. Alvarado1 FLUID FRICTION AND PRESSURE LOSSES

2. Objective To determine experimentally the loss coefficient K for a Venturi meter and straight elbow at different mass flow rates To compare the experimental and theoretical pressure drop values using the Energy equation for different conditions ENTC-303Dr. Alvarado2

3. What we learn from experiment For a given fluid and flow rate, each fitting and length of tubing adds its characteristic pressure drop Pressure drops in tubing are inversely proportional to the diameter Pressure drops in tubing are directly proportional to length Pressure drops in tubing are directly proportional to the flow velocity squared (V 2 ) ENTC-303Dr. Alvarado3

4. Venturi Meter The pressure drop across a gradually converging section, a gradual expansion section and a rapidly diverging diffuser with an area ratio 1:4 following the Venturi meter and a right angled bend are to be compared. ENTC-303Dr. Alvarado4

5. 1. Record the cross sectional area or diameter reading for the Venturi meter at points A, B, C and H. 2. Make sure that the valves in and out of the pump are open. 3. Turn on the water bench pump. 4. Open the flow control valve (white valve) and slowly increase the velocity of the pump until the reading in Siemens Flowmeter starts from 6 GPM. Note: Do not turn on pump with the flow control valve completely closed. ENTC-303Dr. Alvarado5 Procedure

6. 5. Once steady state flow have been reached, record the following: Reading in Siemens Flowmeter. Manometers height readings at A, B, C, D, G and H. 6. Repeat step 4 for the following readings in the Siemens Flowmeter take readings for 2, 3, 4, 5 and 6 GPM. 7. Turn off the water bench and immediately close the flow control valve. (DO NOT TURN OFF!!) ENTC-303Dr. Alvarado6 Procedure

7. Diameters (mm) Area (m 2 ) A B C D,G, H Flow (GPM) H a (mm) H b (mm ） H c (mm ） H d (mm ） H g (mm ） H h (mm ） 6 5 4 3 2 Flow (m 3 /s)VaVa VbVb VcVc VdVd (m/s) Pa-b thPc-d thPa-b realPc-d realK-venturiPa-b realPb-c realPc-d realPg-h real (Pa) A-C(Pa) Average St. Dev.