MECHANICS of FLUIDS LABORATORY - Mechanical Engineering

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CLEANLINESS AND SAFETY Cleanliness There are “housekeeping” rules that the user of the laboratory should be aware of and abide by. Equipment in the lab is delicate and each piece is used extensively for 2 or 3 weeks per semester. During the remaining time, each apparatus just sits there, literally collecting dust. University housekeeping staff are not required to clean and maintain the equipment. Instead, there are college technicians who will work on the equipment when it needs repair, and when they are notified that a piece of equipment needs attention. It is important, however, that the equipment stay clean, so that dust will not accumulate too badly. The Fluid Mechanics Laboratory contains equipment that uses water or air as the working fluid. In some cases, performing an experiment will inevitably allow water to get on the equipment and/or the floor. If no one cleaned up their working area after performing an experiment, the lab would not be a comfortable or safe place to work in. No student appreciates walking up to and working with a piece of equipment that another student or group of students has left in a mess. Consequently, students are required to clean up their area at the conclusion of the performance of an experiment. Cleanup will include removal of spilled water (or any liquid), and wiping the table top on which the equipment is mounted (if appropriate). The lab should always be as clean or cleaner than it was when you entered. Cleaning the lab is your responsibility as a user of the equipment. This is an act of courtesy that students who follow you will appreciate, and that you will appreciate when you work with the equipment. Safety The layout of the equipment and storage cabinets in the Fluid Mechanics Lab involves resolving a variety of conflicting problems. These include traffic flow, emergency facilities, environmental safeguards, exit door locations, etc. The goal is to implement safety requirements without impeding egress, but still allowing adequate work space and necessary informal communication opportunities. Distance between adjacent pieces of equipment is determined by locations of floor drains, and by the need to allow enough space around the apparatus of interest. Immediate access to the Safety Cabinet is also considered. Emergency facilities such as showers, eye wash fountains, spill kits, fire blankets and the like are not found in the lab. We do not work with hazardous materials and such safety facilities are not necessary. However, waste materials are generated and they should be disposed of properly. Every effort has been made to create a positive, clean, safety conscious atmosphere. Students are encouraged to handle equipment safely and to be aware of, and avoid being victims of, hazardous situations. 6
EXPERIMENT 1 FLUID PROPERTIES: DENSITY AND SURFACE TENSION There are several properties simple Newtonian fluids have. They are basic properties which cannot be calculated for every fluid, and therefore they must be measured. These properties are important in making calculations regarding fluid systems. Measuring fluid properties, density and viscosity, is the object of this experiment. W 1 W 2 Part I: Density Measurement. Equipment Graduated cylinder or beaker Liquid whose properties are to be measured Hydrometer cylinder Scale The density of the test fluid is to be found by weighing a known volume of the liquid using the graduated cylinder or beaker and the scale. The beaker is weighed empty. The beaker is then filled to a certain volume according to the graduations on it and weighed again. The difference in weight divided by the volume gives the weight per unit volume of the liquid. By appropriate conversion, the liquid density is calculated. The mass per unit volume, or the density, is thus measured in a direct way. A second method of finding density involves measuring buoyant force exerted on a submerged object. The difference between the weight of an object in air and the weight of the object in liquid is known as the buoyant force (see Figure 1.1). FIGURE 1.1. Measuring the buoyant force on an object with a hanging weight. Referring to Figure 1.1, the buoyant force B is found as B = W 1 - W 2 The buoyant force is equal to the difference between the weight of the object in air and the weight of the object while submerged. Dividing this difference by the volume displaced gives the weight per unit volume from which density can be calculated. Questions 1. Are the results of all the density measurements in agreement? 2. How does the buoyant force vary with depth of the submerged object? Why? Part II: Surface Tension Measurement Equipment Surface tension meter Beaker Test fluid Surface tension is defined as the energy required to pull molecules of liquid from beneath the surface to the surface to form a new area. It is therefore an energy per unit area (F⋅L/L 2 = F/L). A surface tension meter is used to measure this energy per unit area and give its value directly. A schematic of the surface tension meter is given in Figure 1.2. The platinum-iridium ring is attached to a balance rod (lever arm) which in turn is attached to a stainless steel torsion wire. One end of this wire is fixed and the other is rotated. As the wire is placed under torsion, the rod lifts the ring slowly out of the liquid. The proper technique is to lower the test fluid container as the ring is lifted so that the ring remains horizontal. The force required to break the ring free from the liquid surface is related to the surface tension of the liquid. As the ring breaks free, the gage at the front of the meter reads directly in the units indicated (dynes/cm) for the given ring. This reading is called the apparent surface tension and must be corrected for the ring used in order to obtain the actual surface tension for the liquid. The correction factor F can be calculated with the following equation 7
Page 1 and 2: A Manual for the MECHANICS of FLUID
Page 3 and 4: TABLE OF CONTENTS Item Page Report
Page 5: as its strong points. Suggest exten
Page 9 and 10: EXPERIMENT 2 FLUID PROPERTIES: VISC
Page 11 and 12: L level R i y zeroing weight torus
Page 13 and 14: 5. Is a low value of the standard d
Page 15 and 16: pivot balancing weight lever arm wi
Page 17 and 18: Questions 1. Can a similar procedur
Page 19 and 20: actual flow rate (measured in the l
Page 21 and 22: manometer orifice meter venturi met
Page 23 and 24: otameter tank valve motor static pr
Page 25 and 26: Pressure Measurement Equipment A Wi
Page 27 and 28: EXPERIMENT 10 DRAG FORCE DETERMINAT
Page 29 and 30: Experiment II For a number of wings
Page 31 and 32: axis) versus (Q 2 /b 2 h 0 3 g). De
Page 33 and 34: Therefore, Q = ∫ 0 Integration gi
Page 35 and 36: Develop a hydraulic jump in the cha
Page 37 and 38: At any upstream (of the hump) locat
Page 39 and 40: EXPERIMENT 16 MEASUREMENT OF VELOCI
Page 41 and 42: Incompressible Flow Through a Meter
Page 43 and 44: TABLE 16.1. Summary of equations fo
Page 45 and 46: placed on the torque arm to reposit
Page 47 and 48: ∆H = H 2 - H 1 = p 2 ρg + V 2 2
Page 49 and 50: Specific Speed A dimensionless grou
Page 51 and 52: 1 large orifice volume flow rate in

MECHANICS of FLUIDS LABORATORY - Mechanical Engineering

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