For turbulent flow, the pressure drop is dependent on the roughness of the surface, while in marina flow, the roughness effects of the wall are negligible. This is due to the fact that in turbulent flow, a thin viscous layer is formed near the pipe surface which causes a loss in energy, while in laminar flow, this viscous layer is non- existent. Causes of friction loss can include the movement of fluid molecules against one another, or against the inside surface of the pipe and bends, kinks or sharp turns in hose or piping.
This experiment allows us to investigate different scenarios of piping, particularly in roughness, geometry and valves. With the any circuits of flow to chose from the student can combine different variations of each to see how the flow responds. Governing Equations Basic Head Loss for Strait Pipes Head loss can be expressed as a function of friction factor: (CEQ 1) Where HP is head loss, L is length, D is diameter of pipe, V is the velocity of the flow and g is gravity. Flow Rate The flow rate in a pipe can also be calculated using In this case u is used for velocity, Q as volume flow rate and A, cross sectional area of the pipe.
Reynolds Number In fluids, the Reynolds number (Re) is a dimensionless number which gives a assure of the ratio of inertial forces to viscous forces. The Reynolds Number is also used to classify laminar and turbulent flow values. When working with pipes that have different diameters and different flow rates it is easy to make comparisons using Reynolds Number. The calculation of the Reynolds number is as follows: (CEQ 3) Re denotes the Reynolds number, u is the average velocity of the fluid, d is diameter of the pipe and v is the kinematics velocity of the fluid, which for water at ICC we will use the value 1. Xx-6. Bluish Friction Factor The Bluish equation defines only the lower boundary of the friction factor. It can be found using the following: Loss in Strait Pipes The loss from strait pipes can be characterized by a length found by: Head Loss in Bent Pipes These types of losses are represented with a loss factor, k. The equation for head loss in bent pipes then becomes (CEQ 6) Here the k value can either be kill or KGB. Kill denotes total head loss around the bend where KGB is for losses that are due to the bend geometry (likewise with Hal and hub denoting total losses and losses from pipe geometry).
Geometry Figure 1: The +1408 Fluid Friction Apparatus Figure 2: Layout of the Fluid Friction Apparatus In the apparatus shown in Figure 1, there are three main flow circuits which are color coded. The circuits are shown in Figure 2 with each of their labeled components. Each of these circuits have a control valve and selections of pipes and fittings, a list of which can be seen in Table 1. There are pressure tapings that are numbered and fitted at the important points of interest to measure the pressure change along each pipe section. To measure the pressure change across a pipe section there is a free standing viscometer connected.
No included with the Decampment but used in our lab, was a hydraulic bench for the water apply and flow measurement; it can be seen in Figure 3. This tank was used to time the flow rate supplied to the circuits. Table 1: List of pipe fittings and tapings Figure 3: Outlet and weigh tank Experiment Setup and Procedure Before setting up for experiments we must make sure there is no trapped air in the circuits and bleed out any that is. We also had to have any air trapped in the pressure gauge. We then prepared the correct valves to be open and turned on the cold water supply.