Haman Fluid Dynamics of Fire - Lab Report Example

Haman Fluid Dynamics of Fire Name: Course: Instructor: Institution: Date of Submission: 1. Classical Mechanics of Fluids Navier Equations Continuity Equation for incompressible flow = The continuity equation is also identified as the conservation of mass equation. Conservation of momentum equation = mV = momentum amount per unit volume is Φ = ρV Force = F = -σ Net acceleration is given as g is represented as H = ρg (dur.ac.uk, 2017). U=velocity of the fluid P=pressure that the fluid has Ƿ=density µ=fluid dynamic viscosity The equation of continuity equivalence is resolved as presented below (Wikie & Morgan, 2009, 553). The equivalences below display the conservation momentum signifying the conservation of the mass (Richardson, 1989, 75) as to The Navier-Stokes through Linear Momentum it occurs as below: (a) =shows the equation that expresses the transient (b) =convection expression (c) =gravitational pressure (d) =pressure given by the equation (e) =viscous (a) and (b) are representations of the inertial terms (f) =Stress term On stipulation that Re is greater than 1 then to the inertial expressions the viscous term is considered insignificant. When the RE given is high, the Reynolds Navier-Stokes equivalences should be as shown in the following equation (Richardson, 1989, 75): The storage of the computer ought to be superior to the volume of the utmost influential processers currently that help decide the scales. The models of turbulence rely on the scales of wave turbulent as comprised in the exemplary (Marvin & Coakley, 1989, pg 1). The basis of the tenure denotes an inner manufacture of property including energy. According to the conservation of energy equation, the correspondence occurs as shown below (Demirel, 2012, 147). Source = (outflow + storage) – the inflow (Demirel, 2012, 148) 1.2 a rise of 100mm in diameter The inlet of the riser = 1m above ground level. The outlet of the riser = 24m above the ground level. A hose of 45m in length and 80mm in diameter. The fire engine is connected to the inlet of the riser and maintains a constant pressure of 12 (1) draw a diagram to show the system; Hose Riser B (2) 45m A 24m Fire engine (1) Ground 1m (2) e= 0.01m Ϩ=1000kg/m3 Reg=P1/Vi e/d=0.01/0.01=1 1m=0.9*10-3kg/m.s Using Swamme-Fain Equation (2) Pressure of the outlet of the riser = diameter is 100mm using Bernoulli’s equation and the equation of continuity; Bernoulli’s Equation P1/pg+v1/2g+ƶ1=p2/քg+v22/2g+ƶ2+h1 P1=(ƶ2–ƶ1)pg +V22/2 p–V12/2 P+p L/Dv22/2g P1=(25-1)*1000* 9.8+V22/2*1000–12/2*1000+P(24/0.1)V22/(2*9.8) P1=235200+500 V22–7200+12.245 V22p P1=(500=12.245ӻ)V22+163200 (A) To get ӻ by swamme-fain eqn: Re = PVD/μ = 1000*12*0.1/0.9*10-3= 13.3*105 TURBULENT 1/f = -2 log (EID/3.7+5.74/Re0.9) 1/f = -2 log (1/3.7+5.74/ (13.3*105)0.9 Get f = 0.9381 Get P1 = 236854.1pa P1 = 236.8 Kpa V= A1V1 Volume flow rate = Π /µ D2V1 = Π/µ (0.1)2(12) = 0.9425m3/S (3) without friction while using Bernoulli P1/pg +V12/2g+ ƶ1 = P2/pg+v12/2g + ƶ2 P1 = pg(ƶ1 – ƶ1) P1= 1000*9.8 (25-1) P1 = 235200pa P1 =235.2K 2. Dimensional Analysis 2.1 𝜌𝑣𝑎𝑏 𝜇2 P=density V=velocity a&b=length µ=dynamic viscosity Let f=pvab/µ2 The dimensions for the terms in the equation are substituted MaLbTc = [ML-3] [LT-1][L][ML-1T-1]2 Ma= M1+2 a= 3 Lb= L-3+1+1+1-2 b=-2 Tc = T-1 -2 C= -3 M3L-2T-3 Therefore M3/L2T3 2.2 Kolmogorov scale of velocity Kolmogorov scale of velocity T T=f (v k e) 4 variables and three basic dimensions occur M, L, and T. The answer must yield one Π term Π=va kbec T Variables substitution: MoLoTo=[L2/T]a[L2/T3]b[M/L3]c[L/T] Equating the proponents for M,L,&T M:M0=Mc >c=0 L:L0=L2a + 2b + 3c + 1 2a = -2b–1 T:T0=T–a – 3b – 1 2a =-6b–2 Answering the two equations instantaneously a =-¼ b= - ¼ Π1 = V -¼ K - ¼ e0 T Therefore Π = T/ 4 VK 3. Heat Transfer, Thermochemistry and Fluid Dynamics of Combustion 3.1 Wood burning process transpire through combustion. Combustion process refers to the response of all the gases that the material releases. Many materials that directly react to oxygen can be found in wood leading to a high susceptibility of wood to burn consistently. Thermal decomposition occurs through cellulose also plays a major part in ensuring that the ignition and burning processes occur. High temperature in the process of cellulose leads to pyrolyse. The thermal decomposition constituents linger inside, or the gases are unconfined that react with oxygen. Therefore, combustion transpires and great quantities of temperature prompts pyrolysis and burning. Flaring is seen as the fuel temperature is grasped, and a fire starts. Fire occurs when the combustion progression releases the heat, when the heat is large, the fire attained spreads fast and the gasses released are hotter as the surfaces of the fire are limited in an enclosure position. The burning materials describe the rate of the heat released presented as . It is important that one identifies the effect of the external factors presented as which controls the net heat flux. The interior features of a substance affects the release of heat, which develops from the ignition ∆Hc, the gasification of heat Lv, and the aptitude of the heat presented as C. The rate of release of the heat of the materials that are burning transpires as in the calculation: Once the wood begins to burn, the charring process begins; the burning should occur at a continuous process. The frontline amid the pyrolysed and intact wood supervenes the bearing depth of the wood, which ensures the process of pyrolysis. The wood pyrolysing procedure can be replicated to as char leading to the rate of charring depicted as β, which relays to the movement of the anterior pyrolysis proportion (VTT, n.d.). Factors such as the density ρ, are important including the moisture of the burning material given as w symbolized as ,. The charring rate is influenced by an increase in density based on the law of power given as . The charring process frequency increases through the exterior heat flux linearly. Moisture content is given in the equation. 3.2 The time the wood consumes to combust is known as the rate of reaction. Reaction rate is affected by factors that include an order of A + B → C + D, it includes a chemical reaction showing the proponents is equal to two as the rate law shows. The nature of the fire reaction is also a key factor and the concentration of the reaction. Pressure is also a factor that leads to a gaseous rate increase that is equal to the concentration of the gas. The second order of the reaction is also influenced by the first order, which affects the rate of concentration. The second order is influenced by factors such as temperature, solvents, isotopes, and catalysts. It also relies on the reactants orders of concentrations given by the equation below. 4. Characteristics of Flames and Fire Plumes 4.1 Fire plume characteristics derive from the entrainment process that leads to an elevation of the flame. The flow of the fire plume is also a feature that is attained through the laminar and turbulent process. The processes project the flame through a sparkling ray of light on a monitor. When the turbulent process has a high rate, the images are obscure and bright, which leads to an axisymmetric plume that is equal to the production of smoke and temperature The equation below is used for the temperature and small fire smoke production as below: A1=2 f zf (H–d)/2, zf > (H-d) and z ≤ H – d ρa = presents the density Cp = demonstrates the explicit heat of the fire Ta = The temperature ambience H = ceiling height P = Fire perimeter d= the depth of the Hot Gas underneath the Ceiling Af = Fire area The production of smoke is given through the equation below showing the output total calculation, which is: Q = Btu/sec; that is Q*Btu/Sec 4.2 Substance nature is one of the key factors that influences the flame spread on a solid surface. The substances need to be melted, vaporized, or pyrolysis where the heat is delivered right directly to the fuel that leads to the production of vapor. Surface area of the mass influences the flame spread as well. Areas that have high surfaces use combustible materials, which also lead to quick flame spread. The conduct energy is supplied through high density while the low density process lead to a quick movement of the flames. The flames given in liquids are measured in relation to the flash point of the liquid, including temperature where the flame is compelled to spread faster due to the adequate gas. Lower combustion is also responsible for the quick flame spread of gases. Inflammable vapor ought to be in a gaseous state for the flame spread to occur (NFPA, 1998). References Demirel, Y., 2012. Energy: Production, Conversion, Storage, Conservation, and Coupling. New York: Springer Science & Business Media. Marvin, G. J. & Coakley, J. T., 1989. Turbulence Modeling for Hypersonic Flows. NASA Technical Memorandum, pp. 1- 46. NFPA, 1998. Inter Fire Online: Chemistry of Combustion. [Online] Available at: http://www.interfire.org/res_file/9213-1.asp [Accessed 15 3 2016]. Quintiere, G. J., 1998. Principles of Fire Behavior. New York: cengage learning. Richardson, M. S., 1989. Fluid Mechanics. New York: CRC Press. VTT, n.d. Burning of Wood. [Online] Available at: http://virtual.vtt.fi/virtual/innofirewood/stateoftheart/database/burning/burning.html [Accessed 10 3 2016]. Wikie, A. C. & Morgan, B. A., 2009. Fire Retardancy of Polymeric Materials. Second Edition ed. New York: CRC Press. Read More