Ensure that the rubber ball valve in the base of the bucket is open. Its value is found to be 0095. Air bubble was removed from the apparatus. The concept is very similar to sudden expansion in pipe flow, except that hydraulic jumps occur in open-channel flow. Check with your tutor that the mercury Hg manometer is correctly filled; this should not be attempted by students because Hg is a hazardous substance.
Gillesania, Fluid Mechanics and Hydraulics, Engg. The hydraulic bench is shown schematically in Figure 1. Care should be taken that the bucket does not overflow at high flow rates. Eight singularities widely used in distribution networks have also been investigated. You will see that for the major losses, each pipe had three different flow rates passed through it. While the Colebrook equation was used to develop the Moody chart, it is cumbersome to use.
Download file to see next pages Read More. This equation applies only for control volumes which are single streamtubes, i. Last Edited : 30 June 2011 14:00:11. The change in velocity produces large-scale. The shear stress of a flow is also dependent on whether the flow is turbulent or laminar.
Hoffman Clamp white Measuring Cylinder next to outlet pipe Join the test rig inlet pipe to the hydraulic bench flow connector with the pump turned off. The appurtenance encountered by the fluid flow which is a sudden or gradual change of the boundaries results in a change in magnitude, direction or distribution of the velocity of the flow. Great difficulties have been faced by the authors when dealing with minor losses. When outflow occurs from the header tank snap connector, attach the test section supply tube to it, ensuring no air is entrapped. Remove all air from both sections of flexible tubing.
The volume flow rate Q was measured and recorded. This loss is mainly caused either by a diminution in the cross section area due to an accumulation of deposits inside the pipe, or an increase of the ruggedness, or both. To obtain these losses, it is necessary to extend the hydraulic grade lines from the locations of the manometer taps to the elbow and valve Fig. Open the drain valve as soon as the stop watch has been stopped. Analysis As shown in equation 6, minor head losses are expressed as functions of the velocity squared.
Under high pressure and viscosity, positive-displacement pumps would be more efficient compared to centrifugal pumps that function efficiently only on lower values of viscosity and selected pressure point for their susceptibility to obtain frictional losses. Within this intermediate region, the flow is complex involving both friction and turbulence, and it is difficult to separate the effects of the latter from that due to friction. Since h is defined only for single streamtubes and since h is obtained by dividing P by gQ, head is like an intensity in that it is associated with each unit of fluid. More complexity is faced when head losses through singularities are investigated. Minor losses In the case of the minor losses, the observed head loss is due to the loss in the object itself plus pipe friction: You have been given the length between the two tapping points, the flow rate and the observed pressure difference which you convert to h L.
Minor head losses are expressed as: 11 The constant K m is a characteristic of the type of singularity, and its value varies consequently. Ecological imbalance considerations due to dam construction 7. The pipe length between the two piezometer taps is 418 ft. Slowly open air vents at top of water manometer and allow air to enter until manometer levels reach a convenient height, then close the air vent. With the system fully purged of air, close the bench valve, stop the pump, close the outflow valve and remove Hoffman clamps from the water manometer connections. The valve of h 1 and h 2 were measured and recorded.
Evaluation of Energy Losses in Pipes. Gallery Different types of pipes create different amounts of friction thereby impacting on the flow rate. In this practical you will investigate the impact of major and minor losses on water flow in pipes. The difference in manometer heights will indicate the loss in head caused by the fitting. The tubes are connected to a differential water-mercury manometer. For this reason, you have also been given the length of pipe between the two measurements.
The pressure loss between upstream and centre, and centre and downstream tapping points must be taken separately. The best value for K is obtained by curvefitting the experimental data with a power equation in which the exponent is set equal to 2. Evaluation of Energy Losses in Pipes. Open the valve on the instrument panel main control valve. Procedure - Taking a Set of Results Running high flow rate tests Apply a Hoffman clamp to each of the water manometer connection tubes essential to prevent a flow path parallel to the test section.
The energy lost as a result of viscous resistance of the fluid the motion when the flow rate increases, may also be measured as Head Lost. The pump was switched on. Calculations For all of the calculations in this practical you will need to convert the pressure difference into a head measured in metres: Where P 1 and P 2 are respectively the upstream and downstream pressure in Pascals. These were all in 25mm galvanised steel pipe. Their diameter vary from 13 mm to 25 mm, and their surface roughness from smooth to. We followed these same steps to get readings from smooth pipes, rough pipes and losses due to bends. Explicit relations expressing the friction coefficient for all regimes of flow are available.