Minor Losses in Bends and Fittings - Lab Report Example

MINOR LOSSES in bends and fittings Introduction Fluids going through pipes results to brings about loss of pressure that is stated in terms of of equivalent head loss, HL of the fluid passing through the pipe. The pressure (P) and head (H) are related by equation. The loss in pressure is as a result of fluid viscosity why the viscosity is measured by value of coefficient of fluid friction. Just as in the case of friction occurrence in moving solids, shear resistance happening in fluids that have high viscosity are to transform kinetic energy to heat energy that is a representation of loss of energy that is in flowing fluid. The bulk of this energy is changed to heat that brings about warming of fluid while some proportion is lost through radiation and conduction. There can be prediction of pipe work head losses by having separate computation of head losses that comes about as a result of friction between the fluid layers and the inner walls of pipes and then head losses attributable to minor losses, linked to fittings. Minor losses relative to magnitude of head losses as loss coefficient K. Apparatus Figure 1 Procedure This experiment involved measurement of pressure drop across the pipe features by use of piezometer tappings located upstream and downstream of the target fitting. There was connection to multitude manometer, as can be seen in figure 1 , such that pressure drop across each of the fitting was a differential piezometer reading, with the value being expressed in mm. The rate of flow was varied by use of flow control valves, such that the maximum possible flow was registered but taking care that the maximum flow did not reach to a point it became impossible for the manometer menisci could not be seen. There was recording of readings associated with various flow rates with the measurement of Q being in kg/s. Table 1 gives the results from experiment and further calculation have been done to come up with table 2. Calculations In cases that involve bends and fittings in pipes the energy losses incurred is expressed in terms of the equivalent head loss HL (m) that is given by the equation HL = Where K gives the loss coefficient that is dimensionless, g is the gravitational acceleration which is supposed to be constant given in (m/s2) with V being the velocity of the fluid in m/s. For each type of connection there is to be a unique K which is determined experimentally. The aim of this experiment was the determination of k values through experiment for the various pipe fittings and what was obtained then being compared with theoretical values obtained for books and other authentic sources. The pipe diameter of 22.5mm is used in the calculation of velocity in the pipe line. Area of pipeline = 397.61mm2 = 0.0003976m2 Figure 2 Results Table 2 gives the results that were calculated in excel. With the units of V2/2g being in m K will be unitless remembering that HL is in m something that can also be achieved through division of units of V2 by units of g Thus m2/s2 m/s2 = m The plots of H vs V2/2g the fittings are as shown in figure 3 and figure 4. The K values are obtained from the equation on the graphs and are as shown in table 1. Figure 3 Figure 4 Table 1: Comparison on Ks Type of loss K Experimental K from books Mitre 1.617 1.38 Elbow 1.126 1.5 Large bend 0.66 0.46 Enlargement 1.141 5 Contraction 0.307 0.5 Table 2 H2 Q Q Area(1) Area(2) Velocity1 Velocity2 Mitre (mm) (m3/s) (m3/s) (m/s) 154 0.154 0.554 0.000554 0.0003976 0.0006881 1.393360161 1.941452538 1.39336 1.941453 0.098953 0.098953   148 0.148 0.524 0.000524 0.0003976 0.0006881 1.317907445 1.736880033 1.317907 1.73688 0.088526 0.088526   126 0.126 0.514 0.000514 0.0003976 0.0006881 1.292756539 1.67121947 1.292757 1.671219 0.085179 0.085179   104 0.104 0.462 0.000462 0.0003976 0.0006881 1.161971831 1.350178536 1.161972 1.350179 0.068816 0.068816   90 0.09 0.427 0.000427 0.0003976 0.0006881 1.073943662 1.153354989 1.073944 1.153355 0.058785 0.058785   75 0.075 0.392 0.000392 0.0003976 0.0006881 0.985915493 0.972029359 0.985915 0.972029 0.049543 0.049543   53 0.053 0.329 0.000329 0.0003976 0.0006881 0.827464789 0.684697977 0.827465 0.684698 0.034898 0.034898 Elbow 113 0.113 0.554 0.000554 0.0003976 0.0006881 1.393360161 1.941452538 1.39336 1.941453 0.098953 0.098953   102 0.102 0.524 0.000524 0.0003976 0.0006881 1.317907445 1.736880033 1.317907 1.73688 0.088526 0.088526   93 0.093 0.514 0.000514 0.0003976 0.0006881 1.292756539 1.67121947 1.292757 1.671219 0.085179 0.085179   77 0.077 0.462 0.000462 0.0003976 0.0006881 1.161971831 1.350178536 1.161972 1.350179 0.068816 0.068816   64 0.064 0.427 0.000427 0.0003976 0.0006881 1.073943662 1.153354989 1.073944 1.153355 0.058785 0.058785   58 0.058 0.392 0.000392 0.0003976 0.0006881 0.985915493 0.972029359 0.985915 0.972029 0.049543 0.049543   40 0.04 0.329 0.000329 0.0003976 0.0006881 0.827464789 0.684697977 0.827465 0.684698 0.034898 0.034898 Large Bend 62 0.062 0.554 0.000554 0.0003976 0.0006881 1.393360161 1.941452538 1.39336 1.941453 0.098953 0.098953   58 0.058 0.524 0.000524 0.0003976 0.0006881 1.317907445 1.736880033 1.317907 1.73688 0.088526 0.088526   55 0.055 0.514 0.000514 0.0003976 0.0006881 1.292756539 1.67121947 1.292757 1.671219 0.085179 0.085179   45 0.045 0.462 0.000462 0.0003976 0.0006881 1.161971831 1.350178536 1.161972 1.350179 0.068816 0.068816   39 0.039 0.427 0.000427 0.0003976 0.0006881 1.073943662 1.153354989 1.073944 1.153355 0.058785 0.058785   28 0.028 0.392 0.000392 0.0003976 0.0006881 0.985915493 0.972029359 0.985915 0.972029 0.049543 0.049543   22 0.022 0.329 0.000329 0.0003976 0.0006881 0.827464789 0.684697977 0.827465 0.684698 0.034898 0.034898 Enlargement -28 -0.028 0.554 0.000554 0.0003976 0.0006881 1.393360161 1.941452538 0.805116 0.648211 0.033038 0.098953   -26 -0.026 0.524 0.000524 0.0003976 0.0006881 1.317907445 1.736880033 0.761517 0.579908 0.029557 0.088526   -25 -0.025 0.514 0.000514 0.0003976 0.0006881 1.292756539 1.67121947 0.746984 0.557986 0.02844 0.085179   -19 -0.019 0.462 0.000462 0.0003976 0.0006881 1.161971831 1.350178536 0.671414 0.450797 0.022976 0.068816   -12 -0.012 0.427 0.000427 0.0003976 0.0006881 1.073943662 1.153354989 0.620549 0.385081 0.019627 0.058785   -14 -0.014 0.392 0.000392 0.0003976 0.0006881 0.985915493 0.972029359 0.569685 0.324541 0.016541 0.049543   -10 -0.01 0.329 0.000329 0.0003976 0.0006881 0.827464789 0.684697977 0.478128 0.228607 0.011652 0.034898 Contraction 109 0.109 0.554 0.000554 0.0003976 0.0006881 0.805115536 0.648211026 1.39336 1.941453 0.098953 0.033038   100 0.1 0.524 0.000524 0.0003976 0.0006881 0.761517221 0.579908478 1.317907 1.73688 0.088526 0.029557   89 0.089 0.514 0.000514 0.0003976 0.0006881 0.74698445 0.557985768 1.292757 1.671219 0.085179 0.02844   71 0.071 0.462 0.000462 0.0003976 0.0006881 0.671414039 0.450796811 1.161972 1.350179 0.068816 0.022976   63 0.063 0.427 0.000427 0.0003976 0.0006881 0.620549339 0.385081482 1.073944 1.153355 0.058785 0.019627   52 0.052 0.392 0.000392 0.0003976 0.0006881 0.569684639 0.324540588 0.985915 0.972029 0.049543 0.016541   36 0.036 0.329 0.000329 0.0003976 0.0006881 0.478128179 0.228606556 0.827465 0.684698 0.034898 0.011652 References F. M. White, 1999. Fluid Mechanics, McGraw-Hill. B. R. Munson, D.F Young and T. H. Okiisshi, 1998. Fundamentals of Fluid Mechanics, John Wiley and Sons, Inc. . Y. Nakayama and R.F. Boucher, 1999.Intoduction to Fluid Mechanics, Butterworth Heinemann. Y.A. Cengel and J. M. Cimbala, 2006. Fluid Mechanics, McGraw Hill. J.M. McDonough, 2004. Lectures in Elementary Fluid Dynamics: Physics, Mathematics and Applications, University of Kentucky, Lexington. Read More