Loss of head due to change of direction. Mostly used in the U. Holding the outlet steady measure the distance from the bucket water surface to the outlet and the time taken to fill the measuring cup. Frictional or Major Head Losses Frictional head losses are mainly due to the fluid viscosity and the flow regime. The intermediate region downstream of any appurtenance is a mixture of friction and turbulence phenomena, and it is difficult to separate the effects of each one.
The arrangement also allows tests to be conducted on parallel pipe configurations. The depends flow velocity, density and a coefficient for the actual component. He applied the well-known Prandtl mixing length theory, and for smooth turbulent flow, developed a relationship for f which is unfortunately of implicit type requiring a recursive solution. When test conditions have stabilised, the dump valve is lowered, retaining the water in the tank. For the minor losses, a single flow rate was passed through the pipe and the pressure was measured upstream and downstream of several typical objects two valves and an elbow bend.
Determine the slope of the straight line to find n. I also welcome comments through the comments section or via email on improving the demonstrations. Minor loss is caused when there is additional component os added to the straight pipe such as tees, elbows and bend. For high velocities where the flow is fully turbulent, friction loss is caused by water particles coming into contact with irregularities in the surface of the pipe and friction factor itself is a function of surface roughness. See Flow Rate Measurement section.
For example, the stopwatch could be started when the weigh bar, holding a 5 kg mass, first tips. Discuss how these values might change for different flow rates, Reynolds numbers, and pipe size diameter. Tap on the tubing quick connects to release trapped air bubbles, and watch them until they move all the way through the pressure line, through the pressure transducer, and out the bleed valve. Determine the loss coefficients for the two fittings by performing a curvefit to power equation form. Water is fed in from the hydraulics bench via the barbed connector 1 , flows through the network of pipes and fittings, and is fed back into the volumetric tank via the exit tube 23. Carefully undo one of the nuts holding the tubing to the pressure meter until liquid is expelled from the joint.
I would suggest using a more stable platform than piles of books. Further research should be directed towards defining precise minor coefficients by taking into account all the factors involved in such head losses. Open the drain valve as soon as the stop watch has been stopped. The total energy per mass unit in a given point in a fluid flow consists of , and. The water is pumped from reservoir to the pipes network through a closed circuit.
The total head in a fluid flow in a tube or a duct can be expressed as the sum of , and. I also welcome comments through the comments section or via email on improving the demonstrations. They are presented in terms of the linear head loss versus the Reynolds number. For the two smooth pipes for which the results are presented in figure 1 and figure 2, the Hazen-Williams and Darcy approaches seem to be the more able to predicting the head loss. Evaluation of Energy Losses in Pipes.
Also the Hazen-Williams equation only really gives good results when the fluid is Water and can produce large inaccuracies when this is not the case. Depending on the flow rate, it may take some practice, and you may need to try using different containers to measure the flow volume. The Control Valve should always be closed before starting the pump. The main problem here is that the friction factor f varies with the Reynolds number and, therefore, the flow rate. Note: This is a very critical step! You will see that for the major losses, each pipe had three different flow rates passed through it. A great number of studies were carried out in order to achieve a general and precise formulation of the diverse types of head losses. Evaluation of Energy Losses in Pipes.
Method To obtain a series of readings of head loss at different flow rates ,through one or more of the smooth bore test pipes. Compare and discuss the experimental loss coefficients obtained with values in the literature. A stilling baffle is incorporated to reduce turbulence. Connect the clear tubing from the tanks to the low pressure and high pressure inlets of the pressure transducer. You will need to use an appropriate friction factor from your analysis of 25mm galvanised steel pipe in the first part of the experiment major losses.