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1 EXPERIMENTS IN APPLIED FLUID MECHANICS Experiments in Applied Fluid Mechanics: SMT. S. R. PATEL ENGINNERING COLLEGE DABHI, UNJHA PIN CIVIL ENGINEERING DEPARTMENT SUBJECT: Applied Fluid Mechanics SUBJECT CODE: Civil Engineering, S. R. Patel Eng. College, Dabhi Page 0

2 CERTIFICATE This is certify that Mr. / Miss Enrolment No- & Roll No- Of programme has satisfactory completed his/ her term work in course of for the subject code No: for the term (Faculty In- charge) (Internal Examiner) (Date of Submission) Civil Engineering, S. R. Patel Eng. College, Dabhi Page 1

3 INDEX No. Experiment Page No. Date Sign 1. To determine the friction Losses In Pipes. 2. To Draw the velocity diagram by using Wind Tunnel Practical study of Hydraulic Flume and its experimental analysis. To conduct experiments on weirs and to determine the coefficient of discharge. To determine of conjugate depth and loss of specific Energy in a Hydraulic Jump for a given slope To conduct an experiment to find discharge through channel with slope. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 2

4 Experiment 1 Date: FRICTION LOSSES IN PIPES AIM: To determine the friction Losses In Pipes. INTRODUCTION : When fluid through equipment, friction takes places. The calculation of friction with considerable accuracy & missing it, whenever excessive, are important engineering problems. The knowledge of the mechanism of friction & laws applicable to the flow of fluids is useful. THEORY : The friction is a long, straight pipe is totally skin friction. In laminar flow of circular cross section the friction loss is given by welknown Darey s formula for Hagen - Biscuille equation. h = 4 flv 2 2 g d flq hf = 12 d 5 Where, ht = Frictional head loss in meters of water. u = Viscosity of the fluid l = Length of the straight tube in meters. v = Velocity of flowing liquid in m/sec. for 1 equation & in m/hr for equation. d = Diameter of tube in m. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 3

5 = Fluid density Kg/m 3. g = Newton s law conversion factor for 2 equation g is mkg/kg hr 2. And the value of f, Darey gives the following for new pipes of f = ( 1 + ) 400 Where d is the diameter of the pipe in mtrs. PROCEDURE : a. Open the inlet valve completely. b. Control the flow rate of the fluid by means of valve at the outlet. c. After steady state, note down the manometer readings, h t. d. Find out the volumetric flow rate of the liquid by measuring the liquid flow in a known time. e. Take 3 to 4 sets of readings covering laminar, transition & turbulent flow conditions. OBSERVATIONS: Diameter of Small Pipe (d 1 ) : mtr. Diameter of Medium Pipe (d 2 ) : mtr. Diameter of Big Pipe (d 3 ) : mtr. Length of Pipe (L) : 1.5 mtr. Area of Measuring Tank (A) : 0.5 x 0.35 = m 2 Civil Engineering, S. R. Patel Eng. College, Dabhi Page 4

6 OBERVATION TABLE : Head Loss (hf) in mm of Hg Time Required for 50 mm rise of water level in Tank (t) Sec CALCULATION : 1. DISCHARGE ( Q) : A x h = m 3 /Sec t 2. CO-EFFICIENT OF PIPE (f) : f. L. Q 2 hf = 12. d 5 DATA : 1. If the pressure tappings are connected to a U-tube containing mercury & the difference of pressure of indicated by height is h in cm of mercury, then h H = ( ) m of water If the U-tube is used for measuring the flow of liquid having sp.gr.s 1, there sp. gr. of mercury with respect to that liquid is 13.6/s 1. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 5

7 h 13.6 H = ( - 1 ) m of oil. 100 s 1 3. If the meter is connected to an inverted U-tube manometer containing a liquid lighter than the liquid flowing in the horizontal meter & if s 1 = sp. gr. of the liquid flowing through the meter. su = sp. gr. of the liquid used in the U-tube. h = Deflection of the liquid in U-tube in centimeters. h su Then H = ( 1 - ) m of liquid. 100 s 1 Conclusion: Sign Civil Engineering, S. R. Patel Eng. College, Dabhi Page 6

8 Experiment 2 Date: WIND TUNNEL AIM: To Draw the velocity diagram by using Wind Tunnel. INTRODUCTION : Wind tunnel is one of the most important facilitate for experimental work in aerodynamics and fluid flow. Its purpose is to provide a region of controlled air flow into which models can be inserted. This region is termed as the WORKING SECTION. Wind tunnel is closed working section with bell mouth entry. The tunnel is of simplest tube section open type along which air is propelled. The propulsion is usually provided by a fan downstream of the working section. DESCRIPTION : MOUTH AND ENTRY: The entry is shaped to guide the air smoothly into the tunnel. Proper flow separation here would give excessive turbulence and nonuniformity in velocity in the working section. So 2 to 2.5 meter air space is required to entry. Setting chamber and contraction cone to make the flow more parallel and more uniform and to give a little time for turbulence to decay, the mouth is followed by a settling chamber which leads to be contraction to get velocity increase, which is connected with Working section or test section. Contraction is a specially designed carved due to give good results in test section. The setting chamber usually includes a honey comb and nylon mesh screens to filter and stabilize the incoming air flow. WORKING SECTION/ TEST SECTION: (Transparent) It is also called test section as we can fit the models and use this space for experimentation. DATACONE Tunnel is having 300 mm x 300 mm test section with meter length and two windows to insert the models or Probes. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 7

9 DIFFUSER SECTION: The working section is followed by a divergent duct. The divergence results in a corresponding reduction in the flow speed. Diffuser reduces in dynamic pressure leads to reduction in power losses at the exit. Leaving the diffuser, the air enters the lab, along which it flows slowly to get this retardation 1.5 to 2 meter air space is to be provided. FAN AND DRIVE: A six blade fan is fitted to an sturdy frame work and is coupled to a Motor. This motor is controlled with a variable Frequency. Drive - Digital Display which gives smooth variation of air velocity in test section which can be seen on anemometer and one can set the velocity of Air to desired value. Wind tunnel is a basic equipment and experimentation in this equipment has no limits. Open return Tunnel is considered to be simple kind of low speed wind tunnel. The room containing the tunnel is in fact part of the tunnel, since it provides the path by which the air returns from the downstream end to upstream end. SPECIFICATION OF WIND TUNNEL: * TYPE : Open Return NPL wind tunnel. * TEST SECTION / WORKING SECTION : Material: Acrylic Sheet 10 mm Thick. SIZE : 150 mm x 150 mm x 600 mm long. * Blower Fan : 6 Blades M.S. Fan. * A.C. Motor : 5 H.P. - 3,000 RPM 3 H.P Hz * Frequency Drive Controller: - High Frequency Invertor Make : TOSHIBA, MINIELEC MAKE. Model : 400 V; Class VFS7-4037P; 3.7 kw VFD. * AIR VELOCITY IN TEST SECTION : 3 to 30 M/sec. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 8

10 Material : Fibre Reinforced Plastic. AIR LENGTH : 9.5 Meter. CONTRACTION RATIO: 9: 1 PROCEDURE TO CONDUCT THE EXPERIMENT: Before starting the experimentation in wind tunnel carry out the following procedure and read the precautions. 1. Firstly level the equipment using water level by adjusting the leveling studs provided. 2. Alignment of the equipment is essential before operation. The equipment should be aligned such that centre line of equipment will be horizontal. 3. Motor drive requires 3 phase supply. Air speed can be smoothly controlled by varying the speed controlling knob. 4. After preliminary preparation, switch on the 3 phase supply, for starting motor press the push button START. 5. Do not keep any light thing, that is unclamped ( except the models and instruments ) in the tunnel. 6. When the experiments on the models are not going on. Lock the windows ( Test section Acrylic sheets ) perfectly. 7. Handle the models and instruments carefully. 8. After experiments are over, make the 3 phase supply push button off ACCESSORIES SUPPLIED WITH WIND TUNNEL- 1. Multitube Manometer : Height 1 m, Width 500 mm No. of the Tube : 15 PVC tubes, 1 / 4 dia Inclination : Anemometer : Velocity Range 0-30 M/sec Display : Digital. 3. Strain Gauge Balance : Two Channel. Capacity : a) Lift force 0-25 kgs. b) Drag force 0-5 kgs 4. Two Component Digital Force Indicator : Civil Engineering, S. R. Patel Eng. College, Dabhi Page 9

11 to 5 kgs. Two channel, 3 1/2 digit DPM, capable of measuring lift force up to 25 kgs. And drag force up WOODEN MODELS WITH WIND TUNNEL-. 1. Symmetrical Aerofoil Model: 100 mm Wide, 100 mm long, with a Piezzometric tappings and protractor. 2. Unsymmetrical Aerofoil Model: 100 mm wide. 100 mm long, with protractor fitted. 3. Cylindrical Model: 50 x 100 dia., 200 mm long, with a Piezzometric tappings and protractor MULTITUBE MANOMETER: This instrument provides multipoint pressure measuring facility. An element corresponds to the pressure at a point. It consist of a reservoir for the manometer liquid ( water) open to the atmospheric pressure. The reservoir is connected to a number of tubes at the bottom where all the tubes are the point of interest. At which pressure is too measured. There are 15 tubes of the same length. Connections provided to these tubes for connecting the tubes of the other tube coming from the point of interest. Pressures are measured relative to atmospheric datum. PROCEDURE: *. Before starting the experiments the instrument must be leveled carefully, so that the manometer liquid level across all tubes will be constant under static conditions. *. Fill the manometer liquid (water) carefully in the reservoir. See that there are no air bubbles in the manometer, tubes. * In order to increase the sensitivity of manometer, the provision is made for changing the angle of the plane of the tubes. By this the manometer readings are effectively multiplied by convenient factors. By adjusting the inclination of the manometer board, required sensitivity can be obtained. This greatly facilitates the subsequent observations and recording of pressures. * Pressure reading is taken as the difference between the Scale reading and the atmospheric pressure (initial reading) Civil Engineering, S. R. Patel Eng. College, Dabhi Page 10

12 STRAIN GUAGE BALANCE: Strain gauge balance is the system that detects the forces, and is capable of separating the components of total aerodynamic force. The motion of air around the body produce the pressure and velocity variations which produce the aerodynamic forces and moments, that can be experimentally detected and measured in wind tunnel. Fig No. 2 represents model aeroplane and the three dimentional force system, to which it responds. The forces acting on the model are : - 1. Lift The force component acting upwards, perpendicular to the direction of the flight. The aerodynamic lift is produced primarily by the pressure forces acting on the vehicle surface. 2. Drag the net aerodynamic force acting in the same direction. as the undisturbed free- stream velocity. 3. Yaw the component of force in a direction perpendicular to both lift and drag, that tends to move the aeroplane laterally. It is also known as side force. Strain gauge balance has strain gauges as the sensing elements. The system is capable of detecting the two components aerodynamic force- lift and drag. These forces produce strain in various structures of aerodynamic models. Since strain is the fundamental quantity sensed by strain gauge. So the transducers using them are constructed so that physical variable to be instrumented can deform one or more elastic members, to which the gauges are applied. One of the most convenient features of strain gauge transducers is their size. They are usually much smaller than corresponding mechanical instruments. A further advantage arises from the fact that there are electrical output can be indicated and recorded at remote point of greater safety and convenience than the immediate vicinity in which the phenomenon being measured is located. The digital force indicator has two channels - ( i ) for measuring lift force up to 25 kgs. The indicator has 3 1/2 digit DPM with force indication in KG directly. The block diagram of the indicator is shown in figure below (3). Two input sockets are provided for the two channels. Separate zero balance is provided for the two. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 11

13 FROM CHANNEL STRAIN GUAGE SELECTOR BALANCE AMPLI- FIER Before applying input to the respective channel and before starting the experiment check the zero balance for the channel. EXPERIMENTS: 1. FLOW past Aerofoil model and cylindrical model. Aim : To study the pressure distribution around (I) Aerofoil and (ii) Cylinder. Apparatus: Aerofoil and cylindrical model, Multitube manometer. Procedure: Part (I) (for Aerofoil model) 1) Place the aerofoil model in the respective position. 2) Set the angle of model at zero. 3) Connect the piezometric tappings to the multitube manometer. 4) Set the air speed to the desired value. 5) Change the angle of the model and take readings for each tube. 6) Plot the graph of the manometer readings for the fifteen tubes for the various angle. Part (II) (for cylindrical Model) (1) Place the Model appropriately. (2) Set the desired air speed. (3) Connect the piezometric tapping to the manometer. (4) Change the angle of inclination and take manometer readings. (5) Plot the graph of the manometer reading versus angle of inclination. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 12

14 OBSERVATIONS : PART (I) ET NO. ANGLE OF MANOMETER READINGS ( mm of H20 ) INCLIN- ATION m/sec 20 m/sec 30 m/sec Conclusion: Sign Civil Engineering, S. R. Patel Eng. College, Dabhi Page 13

15 Experiment 3 Date: PRACTICAL STUDY OF HYDRAULIC FLUME AND ITS EXPERIMENTAL ANALYSIS AIM: Introduction of Hydraulic Flame. Hydraulic Flume (Tilting type) is essential equipment for Hydraulic Laboratory of technical institutions, for conducting Flow experiments. We have developed an easy to operate tilting type Hydraulic Flume with all its accessories. The unit is accompanied with complete component parts. The main features of the hydraulic flume are 1) Size : 0.3 m. breadth. 0.6 m. height. 10 m. length. 2) Structural design: The complete unit has been designed properly from structural and hydraulic points of view. The side walls of the flume are made of 10 gauge M.S. sheets welded to 1½" angle frame. The flume is mounted on 6" X 3" M.S. channel (two numbers) with ample cross reinforcements. The unit is resting at 3 points, one at the centre and two at the ends. The unit has proved fine during experiments. 3) Transparent section: At the test section, the side walls are made of transparent Perspex sheet for fine visual observation and photographing the flow pattern. The sheet is fixed compactly with the frame to avoid any leakage or. Strain The size of the transparent section at the each side is 120cm x 60cm. 4) Tilting Arrangement: The flume unit consists of an accurate balance: tilting mechanism (patented) which facilitates the operation of the tilting of the flume to the required slope. A pinion and worm wheel arrangement is provided at the centre for quick action. At the each end side of the flume, two rollers rotate along Civil Engineering, S. R. Patel Eng. College, Dabhi Page 14

16 sloped bearing plates, which are connected to the centre arm. Only a little force is required to rotate the wheel, thanks to the accurate design and fine workmanship. 5) Replace able Models : Different types of experiments can be connected in the Hydraulic flume by fitting interchangeable model fittings. The flume has a special arrangement at the teat section, so that the fittings can be interchanged. Experiments such as suppressed weir, spillway, broad crested weir, turbulence study, open channel flow with negative and positive slope, venturi flume, standing way flume, flow pattern etc. Can be carried on with the use of replaceable models. 6) Gates : Two gates, one at the end of the flume, the other at the entrance of test section are provided for regulating the discharge and the head of water, the gates are raised or lowered very easily by C.I. pinion and rack arrangement. The steel gates slide smoothly in G. M. Gates. 7) Flow steadying arrangement: Three fine perforated steel sieves, welded in the pre-entrance section facilitate quick steadying of the flow. 8) Rails : Small rails are fitted on the top sides for easy movement of trolley which carries the Hook gauge. A long scale near the rails and a pointer on the trolley helps to determine the longitudinal and transverse distances along the flume. The extra fittings are accompanied with the flume unit. I. Interchangeable models for II. arrangement. a) Spill way. b) Suppressed weir. c) Long crested weir. Trolley wheel and hook gauge. Trolley wheel assembly and G.M. Hook gauge of 50 cm. length with pinion and rack III. Centrifugal pump set. Centrifugal pump set for supply of water to the flume, centrifugal pump of size 4" x 4" with 10 H.P. motor 440 V, 3 phases with base plate, foot valve switch and starter. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 15

17 IV. Piping System. G.I. pipe system to carry water from the reservoir to the flume through the pump set 6" pipe for delivery side and 6" pipe for suction side with the necessary flanges and bends. V. Orifice unit. G.M. Venturiraeter of size 6" with a differential manometer of 1 m. length. VI. Foundation Bolts and Nuts. The Hydraulic Flume is accompanied with the drawing for foundation and erection. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 16

18 Experiment 4 Date: WEIRS AIM: To conduct experiments on weirs and to determine the coefficient of discharge. DESCRIPTION: Weirs are constructed across the channel to determine the discharge, weirs one of different type. 1) Sharp edged 2) Long crested weir 3) Suppressed weir Sharp edged weirs are made of the brass plates and fixed the channel. The water flows over the weir at the end of the channel. Long crested weirs are having broad crest, such weira are found in lakes and reservoirs. Suppressed weir is also a sharp edged weir but it. Is fixed at the mid portion of the channel. PROCEDURE: 1) Fix the respective weir at the proper place. 2) Adjust the channel for the required slope. 3) Open the Gate II completely. 4) Allow water in the channe 1, so that water just flows over the weir. 5) Take reading in the Hook gauge h1 6) Allow more water, so that there is a head of water over the weir. 7) Take reading in the Hook gauge -h2 8) Collect water in the collecting tank for a particular rise of water R m. 9) Note the time in seconds. 10) Repeat the experiment for different heads. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 17

19 OBSERVATIONS : Diameter of Pipe (d1) : 50 mm. Diameter of Orifice (d2) : 32mm. Area of Pipe (A1) : m2 Area of Orifice (A2) : m2 Width of the weir = B m Head of water over weir = h = h1 - h2 OBERVATION TABLE: Sr. No Manometer Difference In (Hhg) mm. Height over weir Civil Engineering, S. R. Patel Eng. College, Dabhi Page 18

20 CALCULATIONS -1: 1. MANOMETER DIFFERENCE IN TERMS OF WATER COLUMN (H) : S 1 - S 2 = H hg Mtr. Of Water. S 2 2. Actual Discharge ( Q a ) : = Cd X A 2 2 x g x H m 3 /Sec 3. Theoretical Discharge ( Q TH ) : = 2/3 x B X 2 x g x h 3/2 m 3 /Sec Q a 4. Coefficient of discharge = Q th Civil Engineering, S. R. Patel Eng. College, Dabhi Page 19

21 CALCULATIONS -2: Area of the Collecting Tank = a m 2 Rise of water = R m Volume collected = a R m 3 Time taken = t seconds a R m 3 Discharge = Q = t s Width of the channel = B m Velocity before the jump = V 1 = Q B h 1 Froude No. = Fr 1 = /gh 1 From Theory * h 1 * V 1 h 2t = * /1 + 8 Fr * Actual Depth after the jump = h 2 * Find the theoretical h 2t for different h 1 and compare with actual h 2 Civil Engineering, S. R. Patel Eng. College, Dabhi Page 20

22 V 2 1 Energy before Jump = h g 2 Energy after Jump = h V 2 2 g V 2 1 V 2 Loss of Energy = ( h 1 h 2 ) g Conclusion: Sign Civil Engineering, S. R. Patel Eng. College, Dabhi Page 21

23 Experiment 5 Date: HYDRAULIC JUMP AIM: To determine of conjucate depth and loss of specific Energy in a Hydraulic Jump for a given slope. PROCEDURE: 1) Set the channel for a given slope. condition. 2) Remove the venturi flume attachment. 3) Close both the gates I and II. 4) Allow water in the channel. 5) Open the gate II completely. 6) Open the gate I slightly, so that water flows under the gate in supercritical ( shooting ) 7) Close the gate II gently, so that it causes and obstraction to the shooting flow, and a Hydraulic Jump is formed. channel. 8) Regulate the Gate II so finely that the Hydraulic Jump stays at the middle of the 9) With the help of travelling Hook gauge measure the depths of the flow before and after the Hydraulic Jumps say h 1 and h 2 10) Collect water in the collecting tank for a particular rise R m 11) Note the time taken t seconds.repeat experiment for different h 1. CALCUALTION: 1. MANOMETER DIFFERENCE IN TERMS OF WATER COLUMN (H) : S 1 - S 2 = H hg Mtr. Of Water. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 22

24 S 2 2. Actual Discharge ( Q a ) : = Cd X A 2 2 x g x H m 3 /S 3. Slope = i = L h 4. Velocity before the jump = V 1 = B h 1 Q 5. Froude No. = Fr 1 = /gh 1 V 1 6. From Theory * h 1 h 2t = X /1 + 8 Fr Actual Depth after the jump = h 2 Civil Engineering, S. R. Patel Eng. College, Dabhi Page 23

25 V Energy before Jump = h g 2 8. Energy after Jump = h g V 2 V 2 1 V 2 9. Loss of Energy = ( h 1 h 2 ) g Conclusion: Sign Civil Engineering, S. R. Patel Eng. College, Dabhi Page 24

26 Experiment 6 Date: OPEN CHANNEL AIM: To conduct an experiment to find discharge through channel with slope. PROCEDURE : 1) Remove all the models in the channel. 2) Prepare the unit for open channel experiment by lifting both the gates. So that no obstruction is caused to the flow of water. 3) Measure the distance between the Hinge ( over which the channel is tilted) and the pointer. Let it be Lm. 4) By screwing up the wheel of the tilting arrangement the required slope for the channel can be attained. Note the reading in the vertical scale. Let the reading be h m h Then slope = i = Set the channel for a particular slope. 5) Allow water in the channel, so that water flows along the open channel at a steady condition. 6) With the help of point gauge, find the head of water in the channel. Let the Head of water = H m 7) Collect water in the Collecting tank. 8) Note the time taken for a rise R m 9) Repeat the experiment for different Head of water and then for different Slopes. Civil Engineering, S. R. Patel Eng. College, Dabhi Page 25

27 CALCULATIONS : 1. MANOMETER DIFFERENCE IN TERMS OF WATER COLUMN (H) : S 1 - S 2 = H hg Mtr. Of Water. S 2 2. Actual Discharge ( Q a ) : = Cd X A 2 2 x g x H m 3 /Sec Width of channel at inlet = b 1 m Width of channel at throat = b 2 m Height of the water at inlet = h 1 m Q a Velocity at the inlet = V 1 = b 1 h 1 Civil Engineering, S. R. Patel Eng. College, Dabhi Page 26

28 Specific Energy at inlet = E S 1 V 2 1 = h 1 2 g Theoritical discharge : 3/2 m 3 Q t = 1.71 h 2 E s s Q a Coefficient of discharge = Q t Conclusion: Sign Civil Engineering, S. R. Patel Eng. College, Dabhi Page 27

EXPERIMENT No.1 FLOW MEASUREMENT BY ORIFICEMETER

EXPERIMENT No.1 FLOW MEASUREMENT BY ORIFICEMETER 1.1 AIM: To determine the co-efficient of discharge of the orifice meter 1.2 EQUIPMENTS REQUIRED: Orifice meter test rig, Stopwatch 1.3 PREPARATION 1.3.1