Flow Meter Demonstration Apparatus - Lab Report Example

Flow Meter Demonstration Apparatus Table of Contents Table of Contents 1 Executive summary 2 Introduction 3 Objectives 4 Background and Theory 4 Venturi meter: 6 Experimental design 8 Experiment Procedure: 8 Results 9 Discussion 13 Conclusion 15 Executive summary This laboratory experiment highlights the association between pressure and the rate of fluid flow through piping system using a venturi meter. The experiment helps in the understanding of the changes in cross-sectional area of the pipe, which affects the fluid flow rate and the pressure. As the area is constricted, the cross-sectional area decreases thereby increasing the velocity but reducing the pressure significantly. These concepts help in the comprehension of Bernoulli’s effect, because it makes it easy to estimate the differential pressures across the piping system. Most importantly, the experiment was instrumental in opening the eyes of the students on practical application of piping models and how they work with respect to changes in the speed of fluid in the system and how to control such parameters to improve motion of fluids. Introduction Venturi meter was first developed by J.B venture, a scientist with roots from the Italy. The apparatus has immense use in the measurement of the rate of fluid flow along the piping system. Tapering of the piping system generates a system that changes the fluid velocity and pressure along the pipes so that as the pipe constricts, the velocity increases towards the narrow areas of the pipes that attains the maximum velocities. However, as the velocity increases, the pressure decreases significantly, which means that pressure and velocity are inversely proportional to one another. The point in the venturi meter with the narrowest constriction is the throat. The fall in pressure as the water approaches, the throat depends on the increase in velocity, so that high velocities increase the decrease in pressure. Placing manometers along the pipes makes it possible to determine the flow rates along the piping system. The venturi effect is the effect possessed by the meter, which affects the changes in pressure. Venturi effect may also be applicable when using the mixture of gases and liquids, hence testing the same phenomenon under these conditions. When a pump is used to force liquid from one end of the pipe that has a connection with a venturi, the water increases in speed when it approaches areas with narrowest tube. As the water passes through the venturi, it changes towards the wider areas because velocity decreases and pressure peaks. Although the pressure increases after passing through the marrow areas, it does not attain the initial level because of the losses from the friction and turbulent effects that have significant effect on the pressure retention and regeneration. Objectives The flow meter experimental designs help in the identification of problems associated with the application of these concepts in the industry. To achieve the main aims of the study, the following objectives were identified i. To demonstrate the application of flow meters in the measurement of flow rate and velocity in a pipe ii. To calibrate venturi-meter and orifice meter assuming discharge coefficient Cd values as 0.98 and 0.6 respectively iii. To find the values of discharge coefficient Cd of venturi-meter and orifice meter experimentally Background and Theory Piping system that transport fluids require points that engineers can use in controlling the flow. Control of flow requires special mechanics that reduces the pressure generated by the pipe and the fluid flowing inside (Miller, 1996; USBR, 1996). One of the methods used in achieving these specialities is the use of orifice plate. An orifice plate refers to a meter system that one can use to measure the pressure of the fluid flowing in the piping system. To achieve these functions, the orifice plate works by acting as a conduit that ensures restriction along the piping system with the aim of reducing the pressure. Therefore, specific objects are appropriate for reducing and restricting the flow rate, these are the thin sharp edge or venturi, as well as a nozzle. These mechanics are easy to construct and duplicate making them most commonly used (Miller, 1996; USBR, 1996). However, the thin sharp edge model has received favours in the industry making it a standard model for extensive calibration. The virtue that venturi measures the fluid makes it easy for experimental evaluation to assess how its application in measuring the velocity of the pipe, the flow rate can change from one approach of experiment to another. Therefore, this study will assess the application of this model in measuring velocity of pipes and the flow rate as well as the calibration of the model before determining the value of the discharge coefficient (Miller, 1996; USBR, 1996). The term “vena contracta” refers to the pipes minimal cross sectional areas within the jacket. When the fluid flows through the pipe and gets closer to the orifice, its pressure increases (Miller, 1996; USBR, 1996). However, as it passes through the orifice, the pressure begins to drop. The dropping continues until the flow reaches the minimal cross sectional area downstream. The main cause of decreasing pressure when the fluid passes the “vena contracta” is associated with the increasing fluid velocity. A reduction in the area of fluid passage increases the fluid velocity because of the Bernoulli’s effect, making it possible to calculate the discharge. However, as the fluid passes past the narrow areas its velocity declines significantly as the pressure peaks up until it gets to its initial value. Despite the pressure reaching a high value, it will not attain the same initial value because of the losses in turbulence and friction along the stream. This pressure drop is called the differential pressure increases proportional to the rate of fluid flowing in the pipe. Absence of fluid flow does not generate differential pressure (Miller, 1996; USBR, 1996). The piping system used for as flow meter ensures that fluids are transported efficiently from one destination to another. The piping system has various mechanics that enhance the process of transporting fluids. For instance, several mechanics are used in controlling the flow of fluid by restricting the flow through reduced pressures. These applications have immense application in the industrial application hence improving the process of delivering the product to the destination it is required. The normal pipes are used together with the orifice plates to introduce the required mechanics on the pipes. The main function of these features on pipes is to ensure engineers can manage the amount of fluid flowing in the and navigating in the pipes, making it easy in changing fluid pressure along the flow meter. What happens in such cases is that an orifice plate is used at the edge as a way of measuring fluids. When the orifice is fitted with the manometer, one can measure the pressure (Miller, 1996; USBR, 1996). Venturi meter: A venture meter measures the discharge along the pipe. The discharge also refers to the flow of the fluid along the pipe (Miller, 1996; USBR, 1996). The contraction section helps in process of leading the fluid into the area with narrow cross sectional area that is referred to as the throat. This generates increased velocity because the narrow area has smaller pressure but high velocity. The differences in pressure and velocity depend on flow rate (Miller, 1996; USBR, 1996). One can estimate the drop in the pressure. As the fluid goes past the constriction, it gains the pressure and losses the velocity, even though the kinetics recovered may not attain the initial value because of losses in turbulence and friction as shown in the diagram below. Figure 1. Showing a venturi meter Experimental design The equipment system consisted of a slump that stored water. The system required the connectivity to the electrical supply. The water in the slump was transferred to both the test flow meter and the pipe work using the centrifugal pump. The most important fittings called the flow meters were placed on the piping system to aid in the recording of the low velocity and flow rate. The manometers were used for the estimation of pressure losses in these meters. The measuring scale together with a remote tube was fitted with the collection volumetric task for the collection and measuring of the discharge coming from the differential meters. The recycling of water into the tank was attained through the dump valve fitted on the lower level of the tank. Experiment Procedure: The orifice plate was inserted into the required position before making the connection to the mercury manometer. The pipe network was primed with the liquid in the slump tank. The levels of water on both U tubes models were maintained at a uniform level when water was not flowing. Just to make sure that water flows in the tube, the control valve was opened. The flow of water was measured using the stopwatch to obtain the timing and the volumetric tank for the volume. The mercury manometer on the flow meter was used for measuring the differential heads of the tapings. These were repeated three times in the high flow, the middle flow, and the low flow rates Results Table 1: showing the calculation of experimental values used for this laboratory report, Part A. Venturi meter S.no H1(mm) H2(mm) Discharge vol Time/sec (h2-h1) mm (h1-h2)1/2 mm Q(L/s) C 1 175.00 220.00 20.00 23.75 45.00 6.71 0.84 8.37 2 163.00 231.00 20.00 19.44 68.00 8.25 1.03 9.05 3 154.00 241.00 20.00 17.22 87.00 9.33 1.16 10.13 Figure 2: showing the scatterplot of the (h2-h2)^1/2 against the flow rate. The above diagram shows that an increase in the (h2-h1) ^1/2 lead to an increase in the flow rate, this show that the flow rate correlates positively with the (h2-h1) ^1/2 (direct proportion) Figure 3: showing the scatterplot of the flow rate against (h2-h2). The above diagram shows that an increase in the (h2-h1) leads to an increase in the flow rate, this show that the flow rate correlates positively with the (h2-h1) (direct proportion) Figure 4: showing the scatterplot of the discharge coefficient against the flow rate The above diagram shows that an increase in the discharge coefficient leads to an increase in the flow rate, this show that the flow rate correlates positively with the discharge coefficient (direct proportion) The (Energy losses in bends) experiment Table1. Raw data run#1 Fitting Manometer h1 (mm) Manometer h2 (mm) Vol V Liter Time s METER 303 265 5L 27.38 s ELBOW 353 322 SHORT BEND 380 362 ENLARGEMENT 398 404 CONTRACTION 403 380 Table2. Raw data run #2 Fitting Manometer h1 (mm) Manometer h2 (mm) Vol V Liter Time s METER 334 314 5L 38.78s ELBOW 363 346 SHORT BEND 377 368 ENLARGEMENT 385 388 CONTRACTION 387 375 Table3. Raw data run #3 Fitting Manometer h1 (mm) Manometer h2 (mm) Vol V Liter Time s METER 291 247 5L 25.31 s ELBOW 351 315 SHORT BEND 385 362 ENLARGEMENT 405 409 CONTRACTION 412 383 Discussion The graphical representation shown in figures 1 depicting the relationship between (h2-h1)1/2 and the flow rate shows that the value rises with an increase in the flow rate. These phenomenons show that (h2-h1)1/2 is direct proportional to the rate of fluid flow. However, given that this study did not carry out several replicates that could have skewed the study and prevented the actual reflection of the relationship since these variables change from one experimental model to another. Despite such expectations, the study depicted a usual phenomenon previously reported in other experiments using venturi experiments (Miller, 1996; USBR, 1996). These findings prove that when a pump is used to force liquid from one end of the pipe that has a connection with a venturi, the water increases in speed when it approaches areas with narrowest tube. As the water passes through the venturi, it changes towards the wider areas because velocity decreases and pressure peaks (Miller, 1996; USBR, 1996). The relationship between the differential head and the flow rate were examined using figure 3. The scatter plot depicts that an increase in the flow rate correlates positively with an increase in the differential head. These observations were expected because as the flow rate increases so is the differential head. At zero flow rates, there is no differential head. The increase in flow rate affects the changes in differential head so that when the flow rate is high, it correlates to the magnitude of the differential head. This experiment proves the concepts that were previously reported in literature (Miller, 1996; USBR, 1996). What one can note from these observations is that the experimental set up was appropriate and reflected most previous studies that used the same approach in using venturi concept to conduct similar studies. Perhaps the main different in the data recorded in this study is the accuracy of the results but the trends are similar to the existing studies (Miller, 1996; USBR, 1996). Therefore, the flow rate correlates positively and significantly with the differential head. These concepts help in the comprehension of Bernoulli’s effect, because it makes it easy to estimate the differential pressures across the piping system. Most importantly, the experiment was instrumental in opening the eyes of the students on practical application of piping models and how they work with respect to changes in the speed of fluid in the system and how to control such parameters to improve motion of fluids (Miller, 1996; USBR, 1996). The last figure that depicts the relationship between discharge coefficient and the rate of fluid flow shows that as the former rises, the flow rate also rises. These relationships are also directly proportional to one another. Although the experiment forms the fundamental basis in the comprehension of the changes in cross-sectional area of the piping system and the changes in pressure and velocity, it assisted in understanding how to apply the concepts. For instance, as the area is constricted, the cross-sectional area decreases thereby increasing the velocity but reducing the pressure significantly (Miller, 1996; USBR, 1996). Although such experiments are prone to generation of errors, the findings reported in this experiment shows that any error that may have been generated could be minimal not to affect the finding and the general trend of the study (Miller, 1996; USBR, 1996). For instance the experimental model involved processes like opening the control valve and measuring the volume of water as well as the duration using a stopwatch. The use of stopwatch requires attention and close intervention to get accurate data. Any error that could have been generated may vary from one individual to another. Minimising of such errors requires that the same experiment be repeated severally so that a mean value could reflect a reproducible value and minimise the generation error type two thereby making the experiment reproducible. Volume of the water obtains using the volumetric tank may also generate errors owing to the meniscus that is a phenomenon of all liquids (Miller, 1996; USBR, 1996). The students took caution prior to the commencement of the experiment to ensure errors were minimised along the experimental process, a fact that could have played a significant role in ensuring that trends previously reported were replicated. Conclusion The findings show that flow rate, discharge coefficient, (h2-h1), and (h2-h1) ^1/2 correlates positively so that an increase in these values translates to a proportional increase in the flow rates. Venturi effect is the best method for learning and comprehension of Bernoulli’s effect, because it makes it easy to estimate the differential pressures across the piping system. This experiment opened the eye of the students to visualise the application of flow meter and pipe systems at industrial level. Reference Miller, R.W. 1996. Flow measurement engineering handbook. 3rd Ed. McGraw-Hill Book Co., New York, N.Y. USBR.1996. Flow measurement manual. Water resources publication, LLC. Highlands Ranch, CO. . Read More