Air-Flow Rig Measurement - Lab Report Example

Air Flow Student by name Code + Course Name University Name City, State Date Table of Contents List of tables 2 1.Background 3 2.Objectives 3 3.Theory 3 4. Procedure 5 5.Results and calculations 5 6.Discussion and conclusion 9 References and Bibliography 12 List of tables Table 1: test results for venturi 5 Table 2: Test results for static Pitot tube 6 Table 3: Test result Rota meter 7 Table 4: Velocity and mass flow rate for venturi meter 8 Table 5: Velocity and mass flow rate for static pitot tube 9 Figure 1: A graph of flow rate against the velocity of the fluid for a venturi meter 10 Figure 2: A graph of mass flow rate (m3/s ) against velocity m/s 10 1. Background Understanding the flow of fluids has formed a very crucial branch of science and engineering whose knowledge has been exploited in several areas in engineering[ARG16]. The flying principles of aero plane use this principle of operation. By understanding the characteristics of fluids when in flows under different conditions is a key element in this part. In this portion however, we will engage in the studying of the fluid flow in pipe network. There are several methods of measuring fluid flow[BAE15]. This methods includes venturi meters, orifice and Rota meter. The different conditions will be simulated using wind tunnel in the laboratory. In this lab the effects of pipe network configuration, skin friction and pipe fittings have on pressure changes in the pipe. The initial stage of this of this lab will be to learn different methods of measurement[ROU08]. 2. Objectives To take the measurements of air flow by use of the following methods; orifice, Rota meter and venturi meter. 3. Theory The steady flow energy equation below is applied to static-pitot tube and venturi meter so that flow rates at different points can be calculated. (h 1 + 0.5 c 2 1 + g z 1) + = (h 2 + 0.5 c 2 2 + g z 2 ) + Equation 1 + ½ (c 2 2 - c 2 1) + g (z 2 - z 1) = C Equation 2 Where is the rate of heat flow rate of work transfer C is a constant Z1 and z2 are the heights above the convenient reference point C1 and c2 is the velocity with which the air flows with at each state H1 and h2 is the air`s enthalpy at every state and is the mass flow rate of the air. Below are the steps describing how the velocity at the point is derived when there are other parameters given such as the density of the air at both points, pressure at both points and speed is k now for one of the points. Mass flow rate is constant throughout the fluid flow and therefore; 1 A1 V1 = 2 A2 V2 Equation 3 2 and 1 are the air density and are equal. When the equation 3 is rearranged after taking out densities we have; A1 V1 = A2 V2 Equation 4 V2 = Equation 5 In the Bernoulli’s principle we have the equation below; P1 + ½ v 2 1 = p 2 + ½ v 2 2 Equation 6 P1 – p2 + ½ v 2 1 = ½ v 2 2 Equation 7 + v 2 1 = v 2 2 Equation 8 v 2 2 - v 2 1 = Equation 9 v 2 = + v 1 Equation 10 v 1 = Equation 11 v 1 = Equation 12 Equations 11 and 12 applies for pitot static tube and venturi tube respectively[BET14]. 4. Procedure The device was connected to power supply and the flow set to a given value. A thermometer was used to determine the temperature of the fluid flowing. The pressure was measured from the outlet and using equation 2 the mass flow rate was determined. The collected values of the pressure were recorded in the table 1. Using a tape measure, five independent measurements of the dimensions of the venturi meter were taken and recorded. The pressure at the outlet was measured and recorded in table Pitot static tube and equation 2 again, the velocity of air was obtained and the figures recorded in table 3 5. Results and calculations D 1 = 140 mm D 2 = 89 mm Atmospheric pressure = 1016 hPa = 1.23hgm-3 Table 1: test results for venturi 1 Outlet (1-2) p Velocity v1 Mass flow rate m3/s 1 2.6 0 0 0 2 2.9 0.3 0.808212 0.061852 3 2.5 -0.4 1.077615 0.08247 4 2 -0.5 1.347019 0.103087 5 3.21 1.21 3.259787 0.249471 6 3.1 -0.11 0.296344 0.022679 7 2.81 -0.29 0.781271 0.059791 8 2.35 -0.46 1.239258 0.09484 9 3.03 0.68 1.831946 0.140199 10 3.25 0.22 0.592688 0.045358 11 2.9 -0.35 -0.94291 -0.07216 12 2.2 -0.7 1.885827 0.144322 13 2.15 -0.05 0.134702 0.010309 14 2.83 0.68 1.831946 0.140199 15 2.5 -0.33 0.889033 0.068038 16 1.7 -0.8 2.155231 0.16494 mean 2.626875 1.074248 0.082212 Standard deviation 0.440876 0.999575 0.076497 DOF T- value Upper bound Lower bound Table 2: Test results for static Pitot tube 2 Outlet (3-4) p Velocity V1 Mass flow rate 1 2.65 0 0 0 2 2.8 0.15 0.493865 0.037795 3 2.75 -0.05 0.285133 0.021821 4 2.1 -0.65 1.028062 0.078677 5 3.1 1 1.275153 0.097587 6 3.2 0.1 0.403239 0.03086 7 2.9 -0.3 0.69843 0.053451 8 2.35 -0.55 0.945679 0.072373 9 2.7 0.35 0.754391 0.057733 10 1.75 -0.95 1.242866 0.095116 11 3 1.25 1.425665 0.109106 12 2.65 -0.35 0.754391 0.057733 13 1.6 -1.05 1.306643 0.099997 mean 2.580769 0.816424 0.062481 Standard deviation 0.4973 0.438793 0.033581 DOF T- value Upper bound Table 3: Test result Rota meter # 3 Outlet (5-6) p 1 2.30 0 2 3.6 1.3 3 2.71 -0.89 4 2.75 0.04 5 2.4 -0.35 6 2.61 0.21 7 2.85 0.24 8 2.99 0.14 9 2.53 -0.46 10 2.71 0.18 11 2.89 0.18 12 2.5 -0.39 13 2.31 -0.19 14 2.55 0.24 15 2.59 0.04 16 1.89 -0.7 mean 2.63625 Standard deviation 0.370601 DOF T- value Upper bound Area of the pipe = *r2 = *()2 = 6221.946 mm2 = 6.221946 * 10-2 m2 v 1 = for pitot v 1 = = 2.03252m/s when is 0.15 For the rest of values are filled in the table 2 Mass flow rate = A*v* = 6.221946 * 10-2 m2 *1.23 * 0.808212 = 0.061852 m3/s The rest of the mass flow rate are in table 4 and table 5 above Table 4: Velocity and mass flow rate for venturi meter # 1 Velocity v1 Mass flow rate (m3/s) 1 0 0 2 0.808212 0.061852 3 1.077615 0.08247 4 1.347019 0.103087 5 3.259787 0.249471 6 0.296344 0.022679 7 0.781271 0.059791 8 1.239258 0.09484 9 1.831946 0.140199 10 0.592688 0.045358 11 -0.94291 -0.07216 12 1.885827 0.144322 13 0.134702 0.010309 14 1.831946 0.140199 15 0.889033 0.068038 16 2.155231 0.16494 mean 1.074248 0.082212 Standard deviation 0.999575 0.076497 Table 5: Velocity and mass flow rate for static pitot tube 2 velocity Mass flow rate (m3/s) 1 0 0 2 0.493865 0.037795 3 0.285133 0.021821 4 1.028062 0.078677 5 1.275153 0.097587 6 0.403239 0.03086 7 0.69843 0.053451 8 0.945679 0.072373 9 0.754391 0.057733 10 1.242866 0.095116 11 1.425665 0.109106 12 0.754391 0.057733 13 1.306643 0.099997 mean 0.816424 0.062481 Standard deviation 0.438793 0.033581 6. Discussion and conclusion It can be seen from the table 1 and table 2 that different pressures has got different velocities. More so when there is higher difference in pressure so is velocity[DOA80]. For the three methods employed to measure the flow, they have got different accuracies, advantages and disadvantages. The most important thing is to note that the error margin is not big and therefore any of the three can be used anywhere provided they are in good conditions[MEY96]. The graphs below show how mass rate and velocity for venturi and static Pitot tube flow Figure 1: A graph of flow rate against the velocity of the fluid for a venturi meter Figure 2: A graph of mass flow rate (m3/s ) against velocity m/s The mass flow rate is directly proportional to velocity of the air as long as the cross section area of the pipe is kept constant[MEY96] Therefore we can comfortably conclude that, the flow of the fluid has pressure changes along the pipe because of the configuration of the pipe. This pressure drop affects the velocity as well. Pipe joints, t sections and meters along the pipe cause the pressure changes[OWE77]. Pipes are of different radi. This also causes a drop in pressure which in turn affects the velocity of the air. Wind tunnel is the best way to replicate the conditions the flowing air may experience and therefore, the results obtained are relatively accurate[MOD]. Changes in cross section area cause the mass flow rate to change as well. References and Bibliography ARGHODE, V. K., & JOSHI, Y. (2016). Air flow management in raised floor data centers. http://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=1102781. BAECHTEL, J. (2015). Engine airflow: performance theory and applications. [Place of publication not identified], S-A Design. BETTES, H. (2014). Engine airflow hp1537: a practical guide to airflow theory, parts testing, flow bench testing and analyzing data to increase performance for any street or racing engine. New York, HP Books. http://rbdigital.oneclickdigital.com. DOANE, M. K. (1980). Air flow utilization in milking parlors. MEYER, L. A., & WRAY, H. L. (1996). Airflow in ducts. Hayward, CA, LAMA Books. MODERA, M. P. (1995). Airflow performance of building envelopes, components, and systems: [papers presented at a symposium held in Dallas/Ford Worth Airport, TX on 10-11 October 1993]. Philadelphia, Pa, ASTM. OWER, E., & PANKHURST, R. C. (1977). The measurement of air flow. Oxford, Pergamon Press. http://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=922809. ROULET, C.-A. (2008). Ventilation and airflow in buildings: methods for diagnosis and evaluation. Sterling, Earthscan. http://public.eblib.com/choice/publicfullrecord.aspx?p=430170. THOMAS, W. R. (1956). A study of air flow and particle motion in a vortex spray dryer model. THORDARSON, R. (1952). A study of air flow in spray dryer design. Read More