Together they make up the total head losses h lT for pipe flows. For other units - like mm Water Column - check. Due to internal friction and turbulence, this energy is converted into thermal energy. The maximum head produced is 14 m. Water is used at different flow regimes. Frictional or Major Head Losses Frictional head losses are mainly due to the fluid viscosity and the flow regime.
Plot the loss coefficient, K, as a function of the average Reynolds number. It expresses the head loss as a function of diameter, flow rate and length using an empirical coefficient. The knowledge of data of such transformation allows the determination of the necessary power needed for the transportation of the fluid between two points. Ecological imbalance considerations due to dam construction 7. Using your knowledge of manometers, demonstrate whether the difference in elevation of the pressure taps must be considered in reading the difference in manometer height to find the pressure drop caused by the fittings. Determine the loss coefficients for the two fittings at the various flow rates tested. In this experiment we will limit our study to flow through round pipes and pipe fittings, such as elbows and valves.
A regulation valve, a direct rotameter, and water and mercury manometers are used to regulate the fluid flow and to determine the pressure in terms of head difference respectively. Substitute into the Bernoulli equation to find the necessary elevation or pump head. 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. For a pipeline of small length having many minor appurtenances, the total minor head loss can be greater than the frictional head loss. Water manometer Disconnect test section supply tube and hold high to keep it filled with liquid. Thus, it is often useful to estimate the relationship as the head being directly proportional to the square of the flow rate to simplify calculations. When the level in the manometers are steady, note the difference in water levels between the two tubes of the manometers.
The difference in manometer heights will indicate the loss in head caused by the fitting. More complexity is faced when head losses through singularities are investigated. When measurement of the water flow rate is complete, the water is emptied back into the main reservoir. Calculating Flow for a Known Head Obtain the allowable head loss from the Bernoulli equation, then start by guessing a friction factor. This correlation converges well in few iterations. The results presented however do form a set of benchmark data for possible improvement and application in similar cases involving flow transportation inside pipes.
Open the Hoffman clamps and purge any air from the two bleed points at the top of the Hg manometer. The authors feel that more interest should be given to this kind of local losses, and that future investigations should try to take into account all the factors involved in such head losses. Calculation of Head Loss Major Losses The major head loss in pipe flows is given by equation 3. The head is measured in mm. Connect manometer tapping points immediately preceding each fitting under test to the left hand tube of each pair of manometers using the flexible tubing. Pipe flows belong to a broader class of flows, called internal flows, where the fluid is completely bounded by solid surfaces. Open the pump inlet valve to its fully open position.
The biological growth, the obstruction and the encrustation are the most common forms of such deposits which can vary from 1 mm to 10 mm in thickness. In general, a very sudden change to the flow path contributes to significant pressure loss. Explicit relations expressing the friction coefficient for all regimes of flow are available. Evaluation of Energy Losses in Pipes. 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.
This classification into major and minor head losses is rather relative. It is expressed as: 7 The Manning roughness coefficient is solely dependant on the pipe material. The second category called minor or singular head loss is due to the minor appurtenances and accessories present in a pipe network. 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. The Pipe Bends and Fitting Apparatus enables friction losses in various types of pipe fittings to be determined experimentally. The pressure loss between upstream and centre, and centre and downstream tapping points must be taken separately. If there is a time lag between the two, repeat the measurement.
This valve should remain fully open at all times. The same comments can be made for the case of the roughened pipes for which the results are presented in figure 3 and figure 4. Volume m 3 V Measured Volume of water collected in a known Collected time. The F1-18 Pipe Friction Apparatus. With the flow control valve fully open, measure the head loss h shown by the manometer. 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.