Fluid Mechanics : Hydraulic Bench

Objectives: (a) To measure the volume flow rate of water supplied by the Basic Hydraulic Bench (b) To determine the relation between flow rate and pressure of fluid flow

Apparatus: (a) Stopwatch (b) Basic hydraulic bench

Legend: A: Flow control valve B: Bypass valve C: PVC coupling D: Water pump E: Fiberglass sump tank F: Castor wheel G: Sump tank level indicator H: Measuring tank's level indicator I: Fiberglass water channel bench top J: Pressure gauge

K: Ammeter

N: Mains switch

L: Voltmeter

O: Emergency

M: Trip Indicator

stop button

Safety Precaution: (a) Ensure that the sump tank (E) is filled up to at least 3/4 full (G) to prevent dryrunning of the pump. (b) Ensure that the flow control valve (A) and bypass valve (B) are fully open before operating the pump. This is to prevent loading on the pump and to enhance pump lifespan. (c) If the ammeter (K) and voltmeter (L) show a reading but there is no water flow in the pipe, switch of the pump (D) immediately by using the emergency stop button (O). Check the water level in the sump tank. (d) When in operation, always observe the pressure gauge (J) to ensure that the maximum operating pressure of 2 bar (g) is not exceeded. (e) Ensure there is no water leakage from all the joints and fittings (C). Pre-Experiment Procedure: (a) The safety instruction given is read before conducting the experiment. (b) The theory is read and understood the for flow measurement before lab session. (c) The apparatus are make sure in good condition (d) A water hose is connected between the water supply source and water inlet port of the sump tank. (e) The water supply is opened and the sump tank (E) is filled with water up to 3/4 full (G). (f) The power cable is plugged to a 240 V single phase 13 A 50 Hz electrical supply (g). The desired experimental apparatus is desired on the hydraulic bench.

(h) Water hose is connected from the outlet of the hydraulic bench to the inlet of the experiment apparatus. (i) The hydraulic bench is now ready for use.

Procedures: (a) Before conducting the experiment, the flow control valve (A) is ensured and bypass valve (B) of the hydraulic bench are fully open. (b) Then, the mains switch (N) is switched on. (c) The water channel (I) drain port is plugged with the stopper. By using a stopwatch, the time is recorded and the total volume flow accumulated in the water channel is measured by reading the level indicator (H). (d) The flow rate and the water pressure (J) supplied to the experimental apparatus can be varied by adjusting the flow control valve and the bypass valve. The flow rate is adjusted and step (i) is read to obtain readings for 4 different flow rates. (e) The delivery pressure is always ensured does not exceed 2 bar (g). Results: DATA BASIC HYDRAULIC BENCH Run

1

Water

Tim

Discharge

Volumetric Flow

Volumetric Flow

Level

e (s)

Pressure (bar)

Rate (L/s)

Rate (m3/s)

(L) 5

22.0

1.6

0.2272

2.2717 x 10-4

2

7

1 33.0

1.6

0.2120

2.1199 x 10-4

3

10

2 51.0

1.6

0.1960

1.9604 x 10-4

1 TABLE 1: FIRST FLOW RATE Run

Water

Time

Discharge

Volumetric Flow

Volumetric Flow

Level

(s)

Pressure (bar)

Rate (L/s)

Rate (m3/s )

(L) 5 7 10

28.75 45.38 71.07

1.8 1.8 1.8

0.1739 0.1543 0.1407

1.7391 x 10-4 1.5425 x 10-4 1.4071 x 10-4

1 2 3

TABLE 2: SECOND FLOW RATE

Additional Information: (a) Water Collected = Final volume - Initial volume (Read from level indicator) (b) Time Recorded = Time taken between initial & final volume (c) Volumetric Flow Rate = Water Collected / Time Recorded Discussion, Recommendation and Conclusion: a) Calculation of the volume flow rate. Calculation of volume flow rate can be obtained by using the following formula ; 3

Volume flow rate=

Water level (L∨m ) Time ( s)

After the volume flow rate of 3 water run were obtained, the average volume flow rate will need to be determined by adding the 3 values and divide them by 3.

i. For Discharge Pressure of 1.6 Bar. Run 1 : Water level = 5L = 5 x 10-3 m3 Time

= 22.01s

Volume flow rate = 5/22.01 = 0.2272

L/s Volume flow rate = 5 x 10-3/22.01 = 2.2717 x 10-4 m3/s Run 2 : Water level = 7L = 7 x 10-3 m3 Time

= 33.02s

Volume flow rate = 7/33.02 = 0.2120

L/s Volume flow rate = 7 x 10-3/33.02 = 2.1199 x 10-4 m3/s Run 3 : Water level = 10L = 10 x 10-3 m3 Time

= 51.01s

Volume flow rate = 10/51.01 = 0.1960

L/s Volume flow rate = 10 x 10-3/51.01 = 1.9604 x 10-4 m3/s

Avg vol . flow rate=

0.2272+0.2120+0.1960 =0.2117 L/s 3

( 2.2717+2.1199+ 1.9064 ) 10−4 Avg vol . flow rate= =2.1173 × 10−4 m3 /s 3 ii. For Discharge Pressure of 1.8 Bar. Run 1 : Water level = 5L = 5 x 10-3 m3 Time

= 28.75s

Volume flow rate = 5/28.75 = 0.1739

L/s Volume flow rate = 5 x 10-3/28.75 = 1.7191 x 10-4 m3/s Run 2 : Water level = 7L = 7 x 10-3 m3 Time

= 45.38s

Volume flow rate = 7/45.38 = 0.1543

L/s Volume flow rate = 7 x 10-3/45.38 = 1.5425 x 10-4 m3/s

Run 3 : Water level = 10L = 10 x 10-3 m3 Time

= 71.07s

Volume flow rate = 10/71.07 = 0.1407

L/s Volume flow rate = 10 x 10-3/71.07 = 1.4071 x 10-4 m3/s

Avg vol . flow rate=

0.1739+0.1543+0.1407 =0.1563 L /s 3

Avg vol . flow rate=

( 1.7191+ 1.5425+ 1.4071 ) 10−4 =1.5562×10−4 m3 /s 3

b) Graph of Volume (L) vs Time (s) Graph 1: For 1.6 Bar Pressure.

Graph 2 : For 1.8 Bar Pressure

c) Relation between volume and time From the graph plotted above, it can be clearly seen that the volume increase linearly as the time increases. So, as the time increases, the volume also increases.

d) Application of Volume flow rate in daily life and in engineering world. The concept of volume flow rate is undoubtedly very useful to mankind. The concept of volume flow rate can assist everyone in their daily life. There are several applications of volume flow rate that we can recognize in our daily life. Simplest application of volume flow rate is the household faucet. We can adjust the rate of water flowing to either fast or slow depending on our usage. It is easy because we just need to turn the tap and the water flow rate will change to whatever level that you wanted. The system looks simple but there is actually a principle behind it. It applies the concept of volume flow rate. From this experiment, we can see that when the pressure is higher, the volume flow rate will decrease. Therefore, in the household faucet, this concept was applied by increasing the pressure in the faucet itself by controlling its area. When we reduce the area in the pipe by turning the tap, the volume flow rate will decrease hence the speed of water will increase. The volume flow rate also can be applied in engineering world. The most common application in engineering world is in the manufacturing industry. The volume flow rate concept was broadly use in casting. Casting flow rate has a big influence on the structure flow and the steel turbulence intensity in the tundish where the higher the casting volume flow rate, the lower the part of dead zones in the volume of liquid steel. It also influences the kinetics of steel mixing in the tundish. To obtain a better steel mixing in tundish, the higher casting volume flow rate will be used. By increasing the casting volume flow rate, the percentage share of dead volume flow can be decreased and it also increase the well-mixed volume flow. e) Graph of Pressure (bar) vs Volume Flow Rate (litre/s)

f) Relationship between pressure and volume flow rate From the graph plotted above, we can deduce that the pressure is inversely proportional to the volume flow rate. Thus, when the pressure increases, the volume flow rate will decrease. g) Conclusion From this experiment, the volume flow rate of water supplied was successfully obtained by using the Basic Hydraulic Bench. The relationship of flow rate and pressure of fluid flow is the higher the pressure of fluid flow, the lower the volume flow rate of the water.