Fluid Friction Measurements Essay Sample free essay sample

1. Aim: O To find the caput loss. O To find the caput loss associated with flow of H2O through standard adjustments used in plumbing installings. O To find the relationship between clash coefficient and Reynolds’ figure for flow of H2O through a pipe holding a roughened dullard. O To find the H2O speed by utilizing flow measuring devices. 2. Equipment: The trial pipes and adjustments are mounted on a cannular frame carried Castors. Water is fed in from the fluid mechanicss bench via the biting connection ( 1 ) . and is fed back into the volumetric armored combat vehicle via the issue tubing ( 23 ) .  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  ·  · An in-line strainer ( 2 ) An unnaturally roughened pipe ( 7 ) Smooth bore pipes of 4 different diameter ( 8 ) . ( 9 ) . ( 10 ) and ( 11 ) A long radius 90 ° crook ( 6 ) A short radius 90 ° crook ( 15 ) A 45 ° â€Å"Y† ( 4 ) A 45 ° cubitus ( 5 ) A 90 ° â€Å"T† ( 13 ) A 90 ° miter joint ( 14 ) A 90 ° cubitus ( 22 ) A sudden contraction ( 3 ) A sudden expansion ( 16 ) A pipe subdivision made of clear acrylic with a Pitot inactive tubing ( 17 ) A Venturi made of clear acrylic ( 18 ) An opening metre made of clear acrylic ( 19 ) A ball valve ( 12 ) A Earth valve ( 20 ) A gate valve ( 21 ) 3. Theory: 3. 1 Fluid Friction in a Smooth Bore Pipe Two types of flow may be in a pipe: 1 ) Laminar flow at low speeds where H ? V 2 ) Turbulent flow at higher speeds where H ? V N where h the caput loss due to clash. V the fluid speed. and 1. 7 lt ; n lt ; 2. 0. These two types of flow are separated by a passage stage where no definite relationship between Hand V exists. Laminar Transient Turbulent The clash factor. ? . is defined as. ?h =where?h L D V L V2 ? D 2? g the caput loss [ m ] the length between the tapping [ m ] the diameter of the pipe [ m ] the average speed [ m/s ] The Reynolds’ figure. Re. can be found utilizing the undermentioned equation: ? ?V ? D Re =  µ where  µ dynamic viscousness ( 1. 15 ten 10 ?3 Ns/m at 15 °C ) ? the denseness ( 999 kg/m 3 at 15 o C ) For a pipe with a round cross sectional country ; Laminar Flow Re lt ; 2000 Transitional Flow 2000 lt ; Re lt ; 4000 Turbulent Flow Re gt ; 4000 Having established the value of Reynolds’ figure for flow in the pipe. the value of degree Fahrenheit may be determined utilizing a Moody diagram. a simplified version of which is shown below. 3. 2 Head Loss Due to Pipe Fittings The local loss can be estimated as follows ; ?h ( mH 2 O ) =where K V g K ? V2 2?g the fitting â€Å"loss factor† . the average speed of H2O through the pipe [ m/s ] the acceleration due to gravitation [ m/s2 ] . The loss factor is dimensionless and is a map of Reynolds figure. In the standard literature. the loss factor is non normally correlated with Re and raggedness but merely with its geometry and the diameter of the pipe. implicitly presuming that the pipe flow is disruptive. 3. 3 Flow Measurement Orifice home base. Venturi and a Pitot tubing will be used to mensurate the H2O flow rate. For an orifice home base or Venturi. the flow rate and differential caput are related by Bernoulli’s equation with a discharge coefficient added to account for losingss ; 2 ? g ? ?h Q = C vitamin D ? Ao ? ( Ao A1 ) 2 ? 1 where Q the flow rate [ m?/s ] . Cd the discharge coefficient ( Cd = 0. 98 for a Venturi. 0. 62 for an orifice home base ) . A0 the country of the pharynx or opening in m? ( d0 = 14mm for the Venturi. 20mm for the opening home base ) . A1 the country of the pipe upstream m? ( d1 = 24mm ) . the differential caput of H2O [ m ] . ?h g the acceleration due to gravitation [ m/s? ] . For a Pitot tubing. the differential caput measured between the sum and inactive tappings is tantamount to the speed caput of the fluid ; V2 = h1 ? h2 2? g V = 2 ? g ? ( h1 ? h2 )whereV ( h1 ? h2 ) g the average speed of H2O through the pipe [ m/s ] . the differential caput of H2O [ m ] . the acceleration due to gravitation [ m/s? ] . 3. 4 Fluid Friction in a Roughened Pipe Use the same theory explained in 3. 1. 4. Procedure: 4. 1. Fluid Friction in a Smooth Bore Pipe Prime the pipe web with H2O. Open and shut the appropriate valves to obtain flow of H2O through the needed trial pipe. See the diagram screen on the Personal computer. Measure the internal diameter of the trial pipe sample and enter the consequence in the appropriate box on the diagram screen. Adjust the control valve on the F1-10 to give the desired flow rate through the setup. as displayed on the Personal computer. It is normally best to get down the experiment at low flows and work up to higher flows. Use a Moody diagram to gauge the pipe clash factor from the Reynolds’ figure. Enter the clash factor on the diagram screen. Note: This phase of the computations can be carried out after the consequences have been collected if preferred. When the readings on the Personal computer are stable. click ‘GO’ to take a sample. Repeat this for a scope of flow rates between lower limit and upper limit. In normal opera tion. the package should be set to enter utilizing the electronic detectors. However. in order to mensurate really low flow rates it may be necessary to mensurate the flow rate utilizing a measurement cylinder and stop watch. In this instance the package should be set to enter the flow volumetrically. and the volume and clip informations entered in the appropriate boxes on the diagram screen. 4. 2. Head Loss Due to Pipe Fittings Prime the pipe web with H2O. Open and shut the appropriate valves to obtain flow of H2O through the needed trial pipe. Connect the force per unit area detectors to the appropriate tappings for the adjustment you wish to look into. See the diagram screen on the Personal computer. Measure the internal diameter of the largest trial pipe sample and enter the consequence in the appropriate box on the diagram screen. Choose the adjustment under trial from the list. If proving a valve. come in the estimated place of the valve. Adjust the control valve on the F1-10 to give the desired flow rate through the setup. as displayed on the Personal computer. It is normally best to get down the experiment at low flows and work up to higher flows. When the readings on the Personal computer are stable. click ‘GO’ to take a sample. Repeat this for a scope of flow rates between lower limit and upper limit In normal operation. the package should be set to enter utilizing the electronic detectors. However. in order to mensurate really low flow rates it may be necessary to mensurate the flow rate utilizing a measurement cylinder and stop watch. In this instance the package should be set to enter the flow volumetrically. and the volume and clip informations entered in the appropriate boxes on the diagram screen. 4. 3 Flow Measurement 4. 3. 1. Venturi and Orifice Plate: Prime the pipe web with H2O. Open the appropriate valves to obtain flow of H2O through the flow metres. View the diagram screen on the Personal computer. Adjust the control valve on the F1-10 to give the desired flow rate through the setup. as displayed on the Personal computer. It is normally best to get down the experiment at low flows and work up to hig her flows. When the readings on the Personal computer are stable. click ‘GO’ to take a sample. Repeat this for a scope of flow rates between lower limit and upper limit. In normal operation the package should be set to enter utilizing the electronic detectors. However. in order to mensurate really low flow rates it may be necessary to mensurate the flow rate utilizing a measurement cylinder and stop watch. In this instance the package should be set to enter the flow volumetrically. and the volume and clip informations entered in the appropriate boxes on the diagram screen. Note: To mensurate the differential caput developed by the opening home base or Venturi ( for the intent of flow measuring ) connect the investigations to the two tappings on the flow metre organic structure. upstream and at the pharynx ( do non utilize the downstream tapping in the pipe ) . To mensurate the caput loss across the opening home base or Venturi connect the investigations to the upstream tapping on the flow metre organic structure and the tapping in the pipe downstream of the device ( do non utilize the pharynx tapping ) . 4. 3. 2. Pitot Tube: Ensure that the olfactory organ of the Pitot tubing is straight confronting the way of flow and located on the centre line of the pipe. Adjust the control valve on the F1-10 to give the desired flow rate through the setup. as displayed on the Personal computer. It is normally best to get down the experiment at low flows and work up to higher flows. When the readings on the Personal computer are stable. click ‘GO’ to take a sample. Repeat this for a scope of flow rates between lower limit and upper limit. In normal operation the package should be set to enter utilizing the electronic detectors. However. in order to mensurate really low flow rates it may be necessary to mensurate the flow rate utilizing a measurement cylinder and stop watch. In this instance the package should be set to enter the flow volumetrically. and the volume and clip informations entered in the appropriate boxes on the diagram screen. At the maximal flow scene unscrew the waterproofing secretory organ sufficiently to let the Pitot tubing to travel. Traverse the tubing across the diameter of the pipe and detect the alteration in differential caput. Estimate the mean reading obtained and compare this with the maximal reading at the Centre of the pipe. Note: The Pitot tubing is included for the intent of presentation merely. The little differential caput produced by the Pitot tubing means that it should merely be used in applications where high speed is to be measured. Accuracy of measuring on the C6 will be hapless because of the low H2O speed. 4. 4 Fluid in a Roughened Pipe Prime the pipe web with H2O. Open and shut the appropriate valves to obtain flow of H2O through the roughened pipe. Estimate the nominal internal diameter of the trial pipe sample utilizing a Vernier calliper ( non supplied ) . Estimate the raggedness factor k/d. Enter the consequence in the appropriate box on the diagram screen. Load the C6-304 package on the Personal computer and position the diagram screen. Adjust the control valve on the F1-10 to give the desired flow rate through the setup. as displayed on the Personal computer. It is normally best to get down the experiment at low flows and work up to higher flows. When the readings on the Personal computer are stable. click ‘GO’ to take a sample. Repeat this for a scope of flow rates between lower limit and upper limit. In normal operation the package should be set to enter utilizing the electronic detectors. However. in order to mensurate really low flow rates it may be necessary to mensurate the flow rate utilizing a measurement cylinder and stop watch. In this instance the package should be set to enter the flow volumetrically. and the volume and clip informations entered in the appropriate boxes on the diagram screen. 5. Analysis and Discussion For 4. 1: †¢ All readings will be stored by the package and can be viewed in tabular or graphical formats. †¢ Plot a graph of H versus V for each size of pipe. Identify the laminar. passage and disruptive zones on the graphs. †¢ Confirm that the graph is a consecutive line for the zone of laminar flow H ? V. †¢ Plot a graph of log H versus log U for each size of pipe. Confirm that the graph is a consecutive line for the zone of turbulent flow H ? V N. Determine the incline of the consecutive line to happen n. †¢ Compare the values of caput loss determined by computation with those measured utilizing the manometer. †¢ Confirm that the head loss can be predicted utilizing the pipe clash equation provided the speed of the fluid and the pipe dimensions are known. For 4. 2: †¢ Confirm that K is a changeless for each adjustment over the scope of trial flow rates. †¢ Plot a graph of K factor against valve gap for each trial valve. Note the differences in characteristic. For 4. 3: 4. 3. 1: †¢ Compare each calculated flow rate with the existent flow rate measured. †¢ Compare the caput loss across the Venturi and opening at the same flow rate. †¢ Compare the differential caput across the Venturi and orifice home base at the same flow rate. †¢ Comment on the differences in the two devices and their suitableness for flow measuring. †¢ Use the theory covered by 3. 1 to find the K factor for the two flow metres. 4. 3. 2: †¢ Compare each deliberate speed with the measured speed ( determined from the volume flow rate and cross sectional country of the pipe ) . †¢ What is the consequence of the speed profile on the consequences obtained? For 4. 4: †¢ †¢ Plot a graph of pipe clash coefficient versus Re ynolds’ figure ( log graduated table ) . Note the difference from the smooth pipe curve on the Moody diagram when the flow is disruptive.