The Characteristics and Applications of Air-Flow Rig - Lab Report Example

ir-flоw Rig (АNYSY-СFХ) Name: Course Name: Unit Name: Submission Deadline: Table of Contents 1.0 Abstract………………………………………………………….3 2.0 Introduction……………………………………………………..3 2.1 Computational fluid dynamics (CFD)…………………………..3 2.2 Importance……………………………………………………5 2.3 Aim and Objectives……………………………………………..6 3.0 Theory……………………………………………….………….6 3.1 Control volume and flow equation………………………………6 3.2 Bernoulli Equation…………………………………………………..7 3.3 Steady Flow Energy Equation (SFEE)……………………………8 4.0Method……………………………………………………………..9 4.1 Description of CFX methods……………………………………..9 5.0 Results……………………………………………..…………….12 6.0 Result and Discussion…………………………….……………..13 7.0 Experiment Assumptions………………………….……………..17 7.1 Standard condition……………………………………………….17 7.2 Idea gas……………………………………..…………………….18 7.3 Incompressible flow………………………………………………18 7.4 Inviscid flow………………………………………………………18 8. Conclusion………………………………..………………………..19 1.0 Abstract Fluid flow is an important in many physics processes, such as material transportation from one place to another, mixing of chemical and material reactions. This lab experiment will investigate fluid flow in a piping network and several methods will be used to explore this such as venture meters, orifice and rotameter. Using the air tunnel, effect of pipe network configuration, skin friction and pipe fittings on the pressure drop across a pipe will be explored. 2.0 Introduction 2.1 Computational fluid dynamics (CFD) Fluid (liquid and gas) flows are governed by partial differential equations which represent conservative laws for momentum, mass and energy (Hess and Smith, 2003). CFD is the art of science of replacing such partial differential equation systems by a set of algebraic equations which can be solved using computer programs. This are linked each other between weights or density, pressure, the speed or velocity of movement of gas or fluids, and finally temperature of these medium (Hess and Smith, 2003). CF elements rely on the Navier-Stokes equation that is stated as follows: ∂u/∂t + µ x ∇ µ= - ∇ p/p +v∇2µ Where: P= the fluid pressure U= fluid velocity vector Ρ= fluid density ∇2= Laplacian operator, and υ=kinematic viscosity. But, the final equation is represented as : When variables in lab experiment are changed, a person would be able to know how cold air that passed through different conditions at the data center. These results can be upgraded through a cooling base and foreseeable viability of a specific design of IT hardware. Therefore, CFD simulation will be used to understand what kind of variable or adjustments that are needed to cope with extra calories. And this save time and cost for the person carrying out the experiment. This report will use venture system to carry out tests of engine as shown in figure 1 below. Figure 1: Venture test In venturi, the fluid flow is seen to accelerate through a converging cone that has an angle between 15 to 20 degree and the pressure difference between outlet and inlet is measured and this will provide flow rate (Figliola and Beasley, 2007). The fluid flow is slowed where the kinetic energy will be converted back to the pressure energy (Moran and Shapiro, 2010). Venture is mostly preferred where there is availability of small pressures because of its energy recovery capability and high pressure. b. Orifice Plate Fig 2 Orifice Plate The orifice plate usually consists of flat plate that has a circular hole that has been drilled in it. The upstream has a pressure tap and another one that can be found at the bottom i.e. downstream (Moran and Shapiro, 2010). Furthermore, the coefficient of the meter will solely depend on the position of the tap in the orifice plate. c. Pitot tube . Fig 3 Pitot tube The pitot tube has been used in a lot of applications solely in measuring the fluid velocity (Figliola and Beasley, 2007). This is been seen as an inexpensive but very convenient method that can be employed to measure the velocity in the flowing fluid (Figliola and Beasley, 2007). In most cases, Pitot tube is used to measure the air flow in aircraft airspeed measurement and in HVAC applications. 2.2 Importance? CFD was discovered in the early 1950’s and most organizations have used this equipment in in different experiments in their productions (Milne-Thomson, 2005). For example, in car manufacturing companies, it has been employed in exhaust pipe to reduce the impact of environment in order to predict the risk of smoke emitted into the atmosphere. In addition, it has been used to check fire in buildings. CFD is widely used in: Detailed development Design and redesign of systems Solving problems and Complement experimentation, testing 2.3 Aim and Objectives The aim is to study the characteristics and applications of flow measuring devices. Calculate the volume flow rate of fluid from the pressure in in orifice plate, venture meter and Pitot tube devices. To compare between actual volumetric flow and theoretical volumetric flow rate. 3.0 Theory 3.1 Control volume and flow equation In any physics lab experiment theories are important but in real life situation it about numbers. Hence it is important to have proper information and have suitable procedure to solve a real life problem. All these will depend on the way an individual will be able to explain or analyses the experimental results (Hess and Smith, 2003). In our case, it is important to rely on the right outcome. To continue, a mesh design will be created, a simple hand calculations will be used, as well as example of designed that will used to complete the design planning and design procedures. In continuum mechanics and thermodynamics, control volume is used in the process of creating models that are in mathematical in nature (Harlow, 2007). In an inertial frame of reference, it is a volume that is moving with constant flow velocity or fixed in space through which the continuum (solid, liquid or gas) flows. The surface that is used to enclose the control volume is known as the control surface. The main reason why control volume has been used in this lab experiment to analyze fluid flow problems is because it usually taken from the border control for fluid flow such as by the physical limits of its volume flow generating unit (Harlow, 2007). When the control volume is established and different energy that cross the boundary have been known, the below equation can be used to solve the problem. The equation that can be employed in this instanence can be as one of the following: Momentum equation Continuity equation and Energy equation. Transport equation Where: Coefficient of diffusivity (white, 2003). 3.2 Bernoulli Equation Fig 4 Static pressure measurement The static pressure that is depicted as Zp at any point within the duct flow its measurement can carried out through drilling a static pressure hole at the duct wall itself and pressure gauge or manometer tube attached to the wall itself. This is shown as in figure 4. Let us assume that there is frictionless flow in the duct, Bernourlli equation between the two section will be as follows. ………..eq1 Equation 1 can be used to relate average speeds, static pressures and elevations at different locations along the duct. 3.3 Steady Flow Energy Equation (SFEE) The 1st Law of Thermodynamics is a statement of conservation of energy for a thermodynamics system. J/s @ Watt Or q12 - w12 = (h2 –h1) + 1 (C22 – C12) 2 + g (z2-z1) J/kg Where, = mass flow rate of opened system (kg/s) z1 = height at inlet (m) z2 = height at outlet (m) g = acceleration due to gravity (m/s2) h1 = specific enthalpy at inlet of system (kJ/kg) h2 = specific enthalpy at outlet of system (kJ/kg) C2 = mean velocity at outlet of system (m/s) C1 = mean velocity at inlet of system (m/s) T2 = Temperature at outlet (ºC) T1 = Temperature at inlet (ºC) In addition, specific enthalpy is given by h1= CpT1 and h2= CpT2 where Cp is the heat capacity (kJ/kg.K) In SFEE, the mass flow in the inlet is the same at the outlet, thus Moutlet = Minlet When continuity equation is used Flowrate at the outlet = Flow rate at the inlet ρA2C2 = ρA1C1 Where A1=Cross-section area at inlet; A2=Cross-section area at outlet; ρ = density of working fluid If A1 = A2 , so C1 = C2 ­ then Kinetic Energy (KE) = 0 If A1 ≠ A2 , so C1 ≠ C2 ­ then Kinetic Energy (KE) need to be consider. 4.0Method 4.1 Description of CFX methods ANSYS is general purpose software that is mostly used to simulate different interactions of all fields of structural, physics, fluid dynamics, vibration, electromagnetic and heat transfer for engineers. So ANSYS software enables working conditions or simulate tests, it enable test in virtual environment before manufacturing prototypes of different products (Milne-Thomson, 2005). Furthermore, ANSYS improving and determine weak points, foreseeing probable problems and computing life by 3D simulations in virtual environment (Milne-Thomson, 2005). ANSYS software can carry out advanced engineering analyses quickly, practically and safety by its variety of contact algorithms, nonlinear material models and time based loading features (ANSYS, 2003). Figure 1. Modular Structure (ANSYS, 2003) Figure 2. Functions of ANSY (ANSYS, 2003) At this level necessary software was obtained to read the geometry. ANSYS Workbench was set of standard materials such as solid that was used in this test. The figure 3 shows the dimensions of the form, all these figures were estimated except the diameter of the inlet and outlet of venture which was set to 50 mm and 40 mm respectively. Figure 3 Dimensions in Geometry (ANSYS, 2003) 4.2 Mesh After the geometry part has been modelled, the next step was to model the Mesh. The mesh has partial differential equation that can contribute to solve any problem. The mesh was used to carry out test with different numbers of relevance to produce the best network simulation. The relevance numbers that were used was zero and 40. Figure 4 The mesh around the body (ANSYS, 2003) 5.0 Results The solution of system in ANSYS workbench was created and then the results were compared and analyzed through the information about momentum, mass and plot of turbulence, momentum and mass. "Part (A)" V_c= 1800[cm^3/cycle] V1_dot= V_c*3600 [cycle/min] V_dot= V1_dot*convert(cm^3/min,m^3/s) "Part (B)" P0= po# T0= 15[C] V_b= Volume(Air,T=T0,P=P0) V_b1= Volume(Air_ha, T=T0, P=P0) "Part (C)" m_dot= V_dot/V_b m_dot= pi#*D_r^2*150[m/s]/(4*v_b) "Part(D)" v[1]=25 [m/s] D[1]=0.05 [m] D[2]=D_r D[1]^2*v[1]=D[2]^2*v[2] D[3]=0.04[m] D[1]^2*v[1]=D[3]^2*v[3] gamma=cp(Air,T=15[C])/cv(Air,T=15[C]) R=287[J/kg-K] T=convertTemp(C,K,15[C]) Ma=v[2]/sqrt(gamma*R*T) mu=Viscosity(Air,T=15[C]) rho=Density(Air,T=15[C],P=po#) Re=rho*v[2]*D[2]/mu err[1]=0 err[2]=100[%]*(73[m/s]-72.87[m/s])/72.87[m/s] 6.0 Result and Discussion relevance Zero 40 Pressure 72.87 m/s 1, 241 Pa Velocity 73.02 m/s 1,228 Pa In a mesh, the information for CFX about the elements and nodes Domain Nodes Elements Default Domain 16,509 44,052 Figure 6 velocity vs pressure (ANSYS, 2003) Fig 7 Plate of pressure (ANSYS, 2003) From the results, there are two possibilities in which pressure pregnancy can be achieved. The first possibility is when pressure is applied on a thin plate and this will make the part of the plate to grow. The second possibility is to decrease the total pressure per unit area by keeping a force constant that affecting on the part of the plate. As in figure 7 it shows how pressure can be calculated. The results of the amount of the pressure that passed on each plates as shown in the table below The places Pressure inlet 1,212 pa Middle -1,477 pa Outlet -9,383 pa Figure 8: Streamlines (ANSYS, 2003) As noted in figure 9 above, streamline consist of numerous lines around the body and this represent the velocity vector of the fluid flow. This shows the direction of the velocity when it is moving at any point in time (Harlow, 2007). In addition, the ANSYS software can use any form to show the direction of velocity. It has also been seen that density does not change (Milne-Thomson, 2005). Density in the inlet and outlet which was recored as 1186 kg/m3 the reasons for this is an incompressible and this can be depicted in the equation shown below. Figure 9 data from the software (ANSYS, 2003) The data about momentum and mass has been plotted as shown in figure 9. This graph shows that each line do not require a lot of input but need to repeat the steps to get an acceptable level of values and improve the solutions. Those values from EES and ANSYS software were found to be similar, through using the equation below. EES software ANSYS software Velocity 68.18 m/s 72.87 m/s Density 1,225 m/s 1,185 7.0 Experiment Assumptions 7.1 Standard condition This is a benchmark standard that has been set in the lab experiments so that to allow other comparison of various values. The set values of pressure and temperature in chemical and physical processes are important. In this experiment, pressure and temperature will be determined and recorded. There are two standards conditions that will be discussed in this section. a. It is used to measure gases i.e. speed and volume. b. Standard condition can be used to determine testing conditions and used to compare the results of the experiments results with other results. 7.2 Idea gas ………………………..eq2 Where: P is pressure (Pa) V is Volume (cm3) n is a number of moles R is constant and T is temperature (K). An ideal gas is the one in which all the collision between molecules or atoms are perfectly elastic and in which there are no intermolecular attractive forces. There is no perfect gas, however there are many gases that may behave as an ideal gas at normal pressure and temperature. The assumption of kinetic theory of ideal gases is as follows: a. The Molecules of ideal gas moves as rigid balls b. The temperature of the idea gas is directly proportional to the kinetic energy of the molecules. c. No completely negligible the force between the gas molecules. d. The collision between gas molecules is perfectly elastic. 7.3 Incompressible flow Incompressible flow or isochoric flow is a flow where material density is constant which the fluid, or divergence of the flow velocity is zero. Incompressible will not imply that the fluid itself is incompressible. Incompressible flow does not imply that the fluid itself is incompressible. It is shown in the derivation below that even compressible fluids can be modelled as an incompressible flow. Isochoric or incompressible flow is the one in which This is equivalent to saying that ∇ ⋅ u = 0. {\displaystyle \nabla \cdot \mathbf {u} =0.\,} Where:  is the material velocity. 7.4 Inviscid flow This is a flow of inviscid fluid, in which the fluid viscosity is equal to zero. Inviscid flow has a lot of applications in the fluid dynamics. The Reynold number of inviscid flow will approach infinity, as the viscosity approaches zero. When viscous force is neglected, such as in the case of inviscid flow. The Navier-Stokes equation can be simplified to a form known as the Euler equation. Theory of viscous incompressible flow, states that viscous shear stress is directly proportional to the strain of the particles in the liquid with constant viscosity coefficient. 8. Conclusion In conclusion, theoretically calculated velocity at the centre the outlet because it is closer to the theoretical value of the initial velocity is improved simulated more accurately simulate analogy appears to represent. But in this case, it would focus on the values that work out of the simulation. Sometimes the result is not correct. Hence, it should determine to errors of simulation. Extra time, working will be necessary to determine what problems are. References ANSYS, 2003. FIGEES engineering. [Online] Available at: ttp://www.figes.com.tr/english/ansys/ansys.php Figliola, R.S. and Beasley, D.E, 2007. Theory and Design for Mechanical Measurements. Wiley, Hess, J.L and A.M.O. Smith, 2003.. "Calculation of Potential Flow About Arbitrary Bodies". Progress in Aerospace Sciences. 8: 1–138. F.H. Harlow . (2007). "A Machine Calculation Method for Hydrodynamic Problems". Los Alamos Scientific Laboratory report LAMS-1956. Milne-Thomson, L.M.(2005). Theoretical Aerodynamics. Dover Publications Moran. M. J. and Shapiro H. N, 2010. Fundamentals of Engineering Thermodynamics, McGraw Hill, White F.M.,2003, Fluid Mechanics, Seventh edition, McGraw Hill, 2003. Read More