DOCSLIB.ORG

Flame Spread Behavior Characterization of Discrete Fuel Array Under a Forced Flow

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Flame Spread Behavior Characterization of Discrete Fuel Array Under a Forced Flow ARTICLE IN PRESS JID: PROCI [mNS; July 28, 2020;20:40 ] Available online at www.sciencedirect.com Proceedings of the Combustion Institute 000 (2020) 1–9 www.elsevier.com/locate/proci Flame spread behavior characterization of discrete fuel array under a forced flow a b c Giovanni Di Cristina , Nicholas S. Skowronski , Albert Simeoni , c a, d , ∗ Ali S. Rangwala , Seong-kyun Im a Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN, United States b USDA Forest Service, Northern Research Station, Morgantown, WV, United States c Department of Fire Protection Engineering, Worcester Polytechnic Institute, Worcester, MA, United States d Department of Mechanical Engineering, Korea University, Seoul, Republic of Korea Received 8 November 2019; accepted 29 May 2020 Available online xxx Abstract The forced flow driven flame spread behavior along an array of discrete wooden fuel elements was ex- perimentally investigated, which could be an important step to understanding the flow-flame interactions that govern fire spread. Fuel arrays with five different spacings (0.75, 0.875. 1.00, 1.125, and 1.25 cm) were subject to flow speeds ranging from 2.2 to 4.3 m/s at approximately 0.2 m/s intervals. For spacing-flow speed conditions tested in the current study, the flame spread behavior was categorized into three different regimes, continuous, discrete, and quenching, and the regimes were presented in a flammability map. Visual analysis of top and side view video data were used to describe the changing flame behavior and increasing discretiza- tion of the overall flame structure as the flow speed increases. An analysis of the fluid mechanics and heat transfer conditions revealed a correlation between the Stanton number ( St ), the Damkohler number ( Da ), and the onset of flame instabilities and quenching. © 2020 Published by Elsevier Inc. on behalf of The Combustion Institute. Keywords: Flame spread; Quenching; Wood combustion; Flow-flame interaction; Wind-driven fire 1. Introduction Small-sized wooden sticks or dowels have been used to represent the initiation and early buildup of a forest fire, where the first vegetation involving ∗ Corresponding author at: Professor Seong-kyun Im, initial ignition processes are the small leaves, pine Department of Mechanical Engineering, Korea Univer- needles, and branches. Early fire spread research sity, 319 Innovation Hall, 145 Anam-ro Seongbuk-gu, by Fons [1] and Emmons [2 , 3] modeled the con- Seoul 02841, Republic of Korea. secutive ignitions of fuel elements in arrays and E-mail addresses: [email protected] , [email protected] simple fuel beds to represent non-homogeneous (S.-k. Im). forest fuel beds. Since then, researchers have used https://doi.org/10.1016/j.proci.2020.05.035 1540-7489 © 2020 Published by Elsevier Inc. on behalf of The Combustion Institute. Please cite this article as: G.D. Cristina, N.S. Skowronski and A. Simeoni et al., Flame spread behavior characterization of discrete fuel array under a forced flow, Proceedings of the Combustion Institute, https://doi.org/10.1016/j.proci.2020. 05.035 ARTICLE IN PRESS JID: PROCI [mNS; July 28, 2020;20:40 ] 2 G.D. Cristina, N.S. Skowronski and A. Simeoni et al. / Proceedings of the Combustion Institute xxx (xxxx) xxx arrays or fuel beds of wooden sticks, paper strips, flow. For example, in an array of dowels, the igni- cardboard or other simple fuels to simplify the tion of the dowel at position n will depend on the study of complex fire scenarios [1 , 3–12] . flame heat transfer of upstream dowels at positions Vogel and Williams [4] examined the spread ( n-1, n-2 , etc.) that further depend on the upward along square dowels mounted on a plate at different and downward spread rates on each dowel based spacing conditions and found that the spread can on the flow velocity, separation distance, and mate- be accurately approximated using a 1-dimensional rial properties. The problem is further complicated conduction model. Prahl and Tien [5] expanded on by the flame-flow instabilities triggered at certain the work of Vogel and Williams [4] by subjecting flow speed-array spacing conditions. The ability to a similar setup to convective flows of up to 0.9 m/s. predict the onset of such flame instabilities due to While Prahl and Tien [5] predicted the spread rate convective conditions could be the first step in ex- of their wind-driven experiments, they could not tending the accuracy of flame spread models. accurately predict the onset of no propagation for the higher wind speed conditions. Beer [11] de- veloped a purely geometric model for fire spread 2. Experimental setup of arrays subject to flow or slope by using similar assumptions from Vogel and Williams [4] . In Beer’s Wooden dowels with a diameter (d) of 3.2 mm model, the flow (or slope) only serves to tilt the and a length of 14 cm were arranged into in-line flame but does not account for other effects of the arrays. Mounting plates with drilled holes at the flow, such as quenching from high wind speeds. desired spacings were manufactured, and the Although the previous works have demon- dowels were press-fit to the holes. The mounting strated predictions and modeling of fire spread plate was then placed in a small wind tunnel with behaviors under a flow with a relatively low speed a test section that has a cross-sectional area of (below 1.5 m/s), studies for the fire spread behaviors 15.25 cm by 15.24 cm and length of 81.28 cm, as were relatively rare for the flow conditions above schematically illustrated in Fig. 1 a. Flow condi- 1.5 m/s, where the buoyancy effects on the flame tioning screens were utilized to achieve a uniform are still comparable to the effects of momentum flow profile across the height of the wind tunnel from the imposed flow. Furthermore, it has been and minimize fluctuations to less than 5% of the reported that fire spread around the 2.5 mm diam- mean flow. A pilot ignition using a small cotton eter scale becomes unsteady and highly variable wick soaked in 0.1 ml of dodecane initiated the at relatively high flow speeds (around 3 m/s) [13] . fire 1 cm ahead of the first dowel as shown in The propagation and flame behavior changes at Fig. 1 b. The pilot was ignited after turning the flow extinction conditions in fuel arrays have not been on in order to avoid flow unsteadiness from the fan studied previously. Studies for unsteady flames startup. Because the pilot ignition could affect the near extinction have been conducted for single flame propagation, the ignition method was kept cylinders [14] and tandem spheres [15] but not consistent for all experiments. for cylinder arrays. Extensive studies on fluid Flame propagation was measured with two mechanics of single cylinders, tandem cylinders cameras, a GoPro camera facing the dowel array [16–18] , and cylinder arrays and banks [19 , 20] and a Sony DSCIII facing downward. The side inform how the convective flow may interact with camera visualized the flame propagation behavior the cylinders. Such interactions alter the convective while the downward-facing camera captured the heat transfer depending on the separation distance flame wake. The flame propagation behavior was and flow speed. For a reacting flow, the flame-flow studied for 5 spacings ( s = 0.75, 0.875, 1.00, 1.125, coupling can cause unique flame dynamics and and 1.25 cm) under freestream flows of 2.2 to spread behaviors. Finney et al. [21] suggested that 4.3 m/s at approximately 0.2 m/s increments. The unsteady flame convection is strongly dictated by smallest spacing (0.75 cm) was selected based on buoyant and inertial interaction, and the find- the flame size without wind, at which the flame ings could contribute to advancing physics-based barely touches the next dowel. The buoyancy modeling. currents exit the test section before they impact The current study seeks to provide further dis- the ceiling with the flow speeds chosen in the cussion on the flame-flow coupling, arguing that current study, minimizing ceiling effects. For each the common assumptions of continuous increase in spacing-velocity combination, the experiments flame contact or convective heat transfer with an in- were repeated 3 times. In addition to the flame creasing freestream flow speed should be adjusted spread experiments, a hot-wire anemometer was if the flow and fuel setting lead to discretized flame utilized to measure the mean flow speed and tur- behavior. The flame-spread behavior of discrete bulent intensity behind dowel 5 of the array in cold solid fuels was characterized at flow speeds above flows. Measurements were taken approximately 2 m/s for multiple spacing conditions. The system- 6 cm above the base of the tunnel at the centerline atic classification and corresponding analysis of the of the cylinder longitudinal axis. Flow data was flow conditions are used to generate a flammability collected at a half-spacing distance away from map for flame spread on discrete fuels under forced dowel 5 at all spacing conditions. Please cite this article as: G.D. Cristina, N.S. Skowronski and A. Simeoni et al., Flame spread behavior characterization of discrete fuel array under a forced flow, Proceedings of the Combustion Institute, https://doi.org/10.1016/j.proci.2020. 05.035 ARTICLE IN PRESS JID: PROCI [mNS; July 28, 2020;20:40 ] G.D. Cristina, N.S. Skowronski and A. Simeoni et al. / Proceedings of the Combustion Institute xxx (xxxx) xxx 3 3. Results 3.1. Flame propagation behavior characterization From the time the pilot is ignited, the very first dowel is in contact with the flame.
Load more

Recommended publications
  • Chapter 5 Dimensional Analysis and Similarity
    Chapter 5 Dimensional Analysis and Similarity Motivation. In this chapter we discuss the planning, presentation, and interpretation of experimental data. We shall try to convince you that such data are best presented in dimensionless form. Experiments which might result in tables of output, or even mul- tiple volumes of tables, might be reduced to a single set of curves—or even a single curve—when suitably nondimensionalized. The technique for doing this is dimensional analysis. Chapter 3 presented gross control-volume balances of mass, momentum, and en- ergy which led to estimates of global parameters: mass flow, force, torque, total heat transfer. Chapter 4 presented infinitesimal balances which led to the basic partial dif- ferential equations of fluid flow and some particular solutions. These two chapters cov- ered analytical techniques, which are limited to fairly simple geometries and well- defined boundary conditions. Probably one-third of fluid-flow problems can be attacked in this analytical or theoretical manner. The other two-thirds of all fluid problems are too complex, both geometrically and physically, to be solved analytically. They must be tested by experiment. Their behav- ior is reported as experimental data. Such data are much more useful if they are ex- pressed in compact, economic form. Graphs are especially useful, since tabulated data cannot be absorbed, nor can the trends and rates of change be observed, by most en- gineering eyes. These are the motivations for dimensional analysis. The technique is traditional in fluid mechanics and is useful in all engineering and physical sciences, with notable uses also seen in the biological and social sciences.
    [Show full text]
  • Archives of Thermodynamics
    POLISH ACADEMY OF SCIENCES THERMODYNAMICS AND COMBUSTION COMMITTEE archives of thermodynamics QUARTERLY Vol. 38 2017 Wydawnictwo IMP No. 3 Gdańsk Editorial Office Archives of Thermodynamics The Szewalski Institute of Fluid Flow Machinery, Fiszera 14, 80-231 Gdańsk, Poland, Tel.: (+48) 58-341-12-71 int. 141, E-mail: [email protected] http://www.imp.gda.pl/archives-of-thermodynamics/ http://at.czasopisma.pan.pl/ © by the Polish Academy of Science Publication funding of this journal is provided by resources of the Polish Academy of Sciences and the Szewalski Institute of Fluid-Flow Machinery PASci Terms of subscription outside Poland Annual subscription rate outside Poland (2017) is 120 EUR. Price of single issue is 30 EUR. Back of previously published volumes are available on request. Subscription orders should be sent directly to IMP PAN Publishers, The Szewalski Institute of Fluid-Flow Machinery PASci, ul. Fiszera 14, 80-231 Gdansk, Poland; fax: (+48) 58-341-61-44; e-mail: [email protected]. Payments should be transferred to the bank account of IMP PAN: IBAN 28 1130 1121 0006 5498 9520 0011 at Bank Gospo- darstwa Krajowego; Code SWIFT: GOSKPLPW Warunki prenumeraty w Polsce Roczna prenumerata (2017 r.) wynosi 168 PLN. Cena pojedynczego numeru wynosi 42 PLN. Osiągalne są również wydania archiwalne. Zamówienia z określeniem okresu prenumeraty, nazwiskiem i adresem odbiorcy należy kierować bezpośrednio do Wydawcy (Instytut Maszyn Przepływowych im. R. Szewalskiego PAN, ul. Fiszera 14, 80-231 Gdańsk, Aleksandra Nowaczewska, e-mail: [email protected]).
    [Show full text]
  • Summary of Dimensionless Numbers of Fluid Mechanics and Heat Transfer 1. Nusselt Number Average Nusselt Number: Nul = Convective
    Jingwei Zhu http://jingweizhu.weebly.com/course-note.html Summary of Dimensionless Numbers of Fluid Mechanics and Heat Transfer 1. Nusselt number Average Nusselt number: convective heat transfer ℎ퐿 Nu = = L conductive heat transfer 푘 where L is the characteristic length, k is the thermal conductivity of the fluid, h is the convective heat transfer coefficient of the fluid. Selection of the characteristic length should be in the direction of growth (or thickness) of the boundary layer; some examples of characteristic length are: the outer diameter of a cylinder in (external) cross flow (perpendicular to the cylinder axis), the length of a vertical plate undergoing natural convection, or the diameter of a sphere. For complex shapes, the length may be defined as the volume of the fluid body divided by the surface area. The thermal conductivity of the fluid is typically (but not always) evaluated at the film temperature, which for engineering purposes may be calculated as the mean-average of the bulk fluid temperature T∞ and wall surface temperature Tw. Local Nusselt number: hxx Nu = x k The length x is defined to be the distance from the surface boundary to the local point of interest. 2. Prandtl number The Prandtl number Pr is a dimensionless number, named after the German physicist Ludwig Prandtl, defined as the ratio of momentum diffusivity (kinematic viscosity) to thermal diffusivity. That is, the Prandtl number is given as: viscous diffusion rate ν Cpμ Pr = = = thermal diffusion rate α k where: ν: kinematic viscosity, ν = μ/ρ, (SI units : m²/s) k α: thermal diffusivity, α = , (SI units : m²/s) ρCp μ: dynamic viscosity, (SI units : Pa ∗ s = N ∗ s/m²) W k: thermal conductivity, (SI units : ) m∗K J C : specific heat, (SI units : ) p kg∗K ρ: density, (SI units : kg/m³).
    [Show full text]
  • Heat and Mass Correlations
    Heat and Mass Correlations Alexander Rattner, Jonathan Bohren November 13, 2008 Contents 1 Dimensionless Parameters 2 2 Boundary Layer Analogies - Require Geometric Similarity 2 3 External Flow 3 3.1 External Flow for a Flat Plate . 3 3.2 Mixed Flow Over a plate . 4 3.3 Unheated Starting Length . 4 3.4 Plates with Constant Heat Flux . 4 3.5 Cylinder in Cross Flow . 4 3.6 Flow over Spheres . 5 3.7 Flow Through Banks of Tubes . 6 3.7.1 Geometric Properties . 6 3.7.2 Flow Correlations . 7 3.8 Impinging Jets . 8 3.9 Packed Beds . 9 4 Internal Flow 9 4.1 Circular Tube . 9 4.1.1 Properties . 9 4.1.2 Flow Correlations . 10 4.2 Non-Circular Tubes . 12 4.2.1 Properties . 12 4.2.2 Flow Correlations . 12 4.3 Concentric Tube Annulus . 13 4.3.1 Properties . 13 4.3.2 Flow Correlations . 13 4.4 Heat Transfer Enhancement - Tube Coiling . 13 4.5 Internal Convection Mass Transfer . 14 5 Natural Convection 14 5.1 Natural Convection, Vertical Plate . 15 5.2 Natural Convection, Inclined Plate . 15 5.3 Natural Convection, Horizontal Plate . 15 5.4 Long Horizontal Cylinder . 15 5.5 Spheres . 15 5.6 Vertical Channels . 16 5.7 Inclined Channels . 16 5.8 Rectangular Cavities . 16 5.9 Concentric Cylinders . 17 5.10 Concentric Spheres . 17 1 JRB, ASR MEAM333 - Convection Correlations 1 Dimensionless Parameters Table 1: Dimensionless Parameters k α Thermal diffusivity ρcp τs Cf 2 Skin Friction Coefficient ρu1=2 α Le Lewis Number - heat transfer vs.
    [Show full text]
  • A Similarity Analysis for Heat Transfer in Newtonian and Power Law Fluids Using the Instantaneous Wall Shear Stress
    A Similarity Analysis for Heat Transfer in Newtonian and Power Law Fluids Using the Instantaneous Wall Shear Stress Trinh, Khanh Tuoc [email protected] B.H.P. Wilkinson [email protected] Institute of Food Nutrition and Human Health Massey University, New Zealand N.K.Kiaka [email protected] Department of Applied sciences The Papua New Guinea University of technology Abstract This paper presents a technique that collapses existing experimental data of heat transfer in pipe flow of Newtonian and power law fluids into a single master curve. It also discusses the theoretical basis of heat, mass and momentum analogies and the implications of the present analysis to visualisations of turbulence. Key words: Heat transfer, transition, turbulence, Newtonian, power law, instantaneous wall shear stress, similarity plot 1 Introduction The study of heat and mass transfer has been dominated from an early stage by the similar form of the equations of heat, mass and momentum. Following Boussinesq (1877), the transport flux (e.g. of heat) can be defined in terms of an eddy viscosity d q k E (1) h dy where is the temperature y the normal distance from the wall k the thermal conductivity Eh the eddy thermal diffusivity q the rate of heat transfer flux the fluid density Equation (1) may be rearranged as y q q w dy (2) E 0 1 h k which is very similar to the equation for momentum transport y U w dy (3) E 0 1 Where U U u* , y yu* yu* and Cp w u* q w have been normalised with the friction velocity u* w and the fluid apparent viscosity .
    [Show full text]
  • On Dimensionless Numbers
    chemical engineering research and design 8 6 (2008) 835–868 Contents lists available at ScienceDirect Chemical Engineering Research and Design journal homepage: www.elsevier.com/locate/cherd Review On dimensionless numbers M.C. Ruzicka ∗ Department of Multiphase Reactors, Institute of Chemical Process Fundamentals, Czech Academy of Sciences, Rozvojova 135, 16502 Prague, Czech Republic This contribution is dedicated to Kamil Admiral´ Wichterle, a professor of chemical engineering, who admitted to feel a bit lost in the jungle of the dimensionless numbers, in our seminar at “Za Plıhalovic´ ohradou” abstract The goal is to provide a little review on dimensionless numbers, commonly encountered in chemical engineering. Both their sources are considered: dimensional analysis and scaling of governing equations with boundary con- ditions. The numbers produced by scaling of equation are presented for transport of momentum, heat and mass. Momentum transport is considered in both single-phase and multi-phase flows. The numbers obtained are assigned the physical meaning, and their mutual relations are highlighted. Certain drawbacks of building correlations based on dimensionless numbers are pointed out. © 2008 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Keywords: Dimensionless numbers; Dimensional analysis; Scaling of equations; Scaling of boundary conditions; Single-phase flow; Multi-phase flow; Correlations Contents 1. Introduction .................................................................................................................
    [Show full text]
  • Radiation and Chemical Reaction Effects on Thermophoretic MHD Flow Over an Aligned Isothermal Permeable Surface with Heat Source
    Chemical and Process Engineering Research www.iiste.org ISSN 2224-7467 (Paper) ISSN 2225-0913 (Online) Vol.31, 2015 Radiation and Chemical Reaction Effects on Thermophoretic MHD Flow over an Aligned Isothermal Permeable Surface with Heat Source C S K Raju 1 N.Sandeep 1* M.Jayachandra Babu 1 V.Sugunamma 2 1.Department of Mathematics, VIT University, Vellore (T.N.) - 632014, India 2.Department of Mathematics, Sri Venkateswara University, Tirupati (A.P.) -517502, India E-mail: [email protected] Abstract Radiation and chemical reaction effects on thermophoretic MHD flow over an inclined isothermal permeable surface in presence of heat generation/absorption, viscous dissipation is analyzed numerically. The governing equations are reduced to nonlinear ordinary differential equations by using similarity transformation and then solved numerically using bvp4c solver with MATLAB Package. The effects of governing parameters on dimensionless quantities like velocity, temperature, concentration, skin friction, wall heat flux and wall deposition flux are discussed for both suction and injection cases. Results are presented graphically and through tables. Keywords: Magnetohydrodynamics, Thermophresis, Radiation, Dissipation, Heat source. 1. Introduction Thermophoresis has potential applications like air cleaning, aerosol particles sampling, nuclear reactor safety, micro electronics manufacturing etc. Thermophoresis describes the migration of suspended small micron sized particles in a non isothermal gas to the direction with decreasing thermal gradient and the velocity acquired by the particle is known as thermophoretic velocity. The detailed discussion about this study was given by (Derjaguin and Yalamov, 1965). Thermophoresis of aerosol particles in laminar boundary layer on flat plate was analyzed by (Goren, 1977). Thermophoretic hydromagnetic flow over radiate isothermal inclined plate by considering heat source was discussed by (Noor et.al, 2013).
    [Show full text]
  • The Turbulent Boundary Layer: Experimental Heat Transfer with Strong Favorable Pressure Gradients and Blowing
    THE TURBULENT BOUNDARY LAYER: EXPERIMENTAL HEAT TRANSFER WITH STRONG FAVORABLE PRESSURE GRADIENTS AND BLOWING By D. W. Kearney, R. J. Moffat and W. M. Kays Report No. HTMT-12 Prepared Under Grant NASA JGi--0"5-020-134 for The National Aeronautics and Space Administration (ACCESSION NUMBER) T RU) (CDE) V 0 ' (NASA c1 OR TMX OR NUMBER) 4pY Thermpsciences Division Deparime tof Mechanical Engineering vStanford University Stanford, California April 1970 Reproduced by NATIONAL TECHNICAL I INFORMATION SERVICE U S Departmnt f Commerce -- - - Springfield-- VA 22151 THE TURBULENT BOUNDARY LAYER: EXPERIMENTAL HEAT TRANSFER WITH STRONG FAVORABLE PRESSURE GRADIENTS AND BLOWING By D. W. Kearney, R. J. Moffat and W. M. Kays Report No. HMT-12 Prepared Under Grant NASA NGL-05-020-134 for The National Aeronautics and Space Administration Thermosciences Division Department of Mechanical Engineering Stanford University Stanford,California April 1970 fBgE0IOPAGE .- BSANK NOT FILMED. ACKNOWLEDGMENTS This research was made possible through grants from the National Science Foundation, NSF GK 2201, and the National Aeronautics and Space Administration, NGL 0,5-020-134. The authors wish to express appreciation for the interest of Dr. Royal E. Rostenbach of NSF, and Dr. Robert W. Graham of NASA Lewis Laboratories. The cooperation of R. J. Loyd throughout the experi­ mental program was a necessary factor in its success. The assistance of B. Blackwell and P. Andersen in part of the testing is appreciated. Special credit is due Miss Jan Elliott for her timely and competent handling of the publi­ cation process. iii ABSTRACT Heat transfer experiments have been carried out in air on a turbulent boundary layer subjected to a strongly accelerated free-stream flow, with and without surface transpiration.
    [Show full text]
  • An Experimental Investigation of Simultaneous Heat-Flux And
    AIRFOIL, PLATFORM, AND COOLING PASSAGE MEASUREMENTS ON A ROTATING TRANSONIC HIGH-PRESSURE TURBINE DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Jeremy B. Nickol, M.S. Graduate Program in Mechanical Engineering The Ohio State University 2016 Dissertation Committee: Professor Randall M. Mathison, Advisor Professor Michael G. Dunn, Co-Advisor Professor Sandip Mazumder Professor Jeffrey P. Bons Copyright by Jeremy B Nickol 2016 ABSTRACT An experiment was performed at The Ohio State University Gas Turbine Laboratory for a film-cooled high-pressure turbine stage operating at design-corrected conditions, with variable rotor and aft purge cooling flow rates. Several distinct experimental programs are combined into one experiment and their results are presented. Pressure and temperature measurements in the internal cooling passages that feed the airfoil film cooling are used as boundary conditions in a model that calculates cooling flow rates and blowing ratio out of each individual film cooling hole. The cooling holes on the suction side choke at even the lowest levels of film cooling, ejecting more than twice the coolant as the holes on the pressure side. However, the blowing ratios are very close due to the freestream massflux on the suction side also being almost twice as great. The highest local blowing ratios actually occur close to the airfoil stagnation point as a result of the low freestream massflux conditions. The choking of suction side cooling holes also results in the majority of any additional coolant added to the blade flowing out through the leading edge and pressure side rows.
    [Show full text]
  • The Pennsylvania State University the Graduate School College of Engineering IMPLEMENTATION of HIGH FST TURBULENT KINETIC ENERGY
    The Pennsylvania State University The Graduate School College of Engineering IMPLEMENTATION OF HIGH FST TURBULENT KINETIC ENERGY DIFFUSION MODEL IN OPENFOAM CODE FOR SIMULATION OF HEAT TRANSFER OVER A GAS TURBINE BLADE A Thesis in Mechanical Engineering by Vedant Chittlangia © 2017 Vedant Chittlangia Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science December 2017 The thesis of Vedant Chittlangia was reviewed and approved∗ by the following: Savas Yavuzkurt Professor of Mechanical Engineering Thesis Advisor, Chair of Committee Anil Kulkarni Professor of Mechanical Engineering Thesis Reader Karen Thole Distinguished Professor of Mechanical Engineering Head of the Department of Mechanical Engineering ∗Signatures are on file in the Graduate School. ii Abstract Several low-Reynolds number turbulence models are compared for their performance to predict the effect of free-stream turbulence on skin friction coefficient and Stanton number. Initial ef- forts were made to implement a turbulent kinetic energy diffusion model in FLUENT but due to unavailability of the source code the focus was shifted to OpenFOAM, an open-source CFD software. Effect of initial values of free-stream parameters is studied on a flat plate. Launder- Sharma model is modified to account for the effect of free-stream turbulence and length scale by incorporating variable cµ and an additional diffusion term in turbulent kinetic energy trans- port equation. Comprehensive study is carried for better predictions of skin friction coefficient, Stanton number and turbulent kinetic energy profile on a flat plate for different initial turbulent intensities of 1%, 6.53% and 25.7%. The new model is validated for its better performance on a flat plate to predict Stanton number, skin friction coefficient and turbulent kinetic energy profile with close match to the data points.
    [Show full text]
  • An Investigation of Heat Transfer Within Regions of Separated Flow at a Mach Number of 6.0
    NASA TECHNICAL NOTE AN INVESTIGATION OF HEAT TRANSFER WITHIN REGIONS OF SEPARATED FLOW AT A MACH NUMBER OF 6.0 by Paul F. HoZZoway, James Re Sterrett, and Helen S. Creekmore Langley Research Center Lungley Station, Hampton, Va, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION - WASHINGTON, D. C. I TECH LIBRARY KAFB, NY AN INVESTIGATION OF HEAT TRANSFER WITHIN REGIONS OF SEPARATED FLOW AT A MACH NUMBER OF 6.0 By Paul F. Holloway, James R. Sterrett, and Helen S. Creekmore Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - Price $3.00 AN INVESTIGATION OF HEAT TRANSFEZ WITHIN REGIONS OF SEPARATED now AT A MACH NUMBER OF 6.0 By Paul F. Holloway, James R. Sterrett, and Helen S. Creekmore LEtngley Research Center An extensive systematic investigation of the heat transfer associated wlth 1 regions of laminar, transitional, and turbulent separation has been conducted on sharp- and blunt-leading-edge flat plates at a Mach number of 6.0 over a free-stream unit Reynolds number range of approximately 1 x lo6 to 8 x lo6 per foot. Separated regions were forced by forward- and rearward-facing steps, and by loo, 20°, 30°, and 40° wedges located in several longitudinal positions on the plate. It has been shown that upon proper classification of the several types of separated flow, the trends of the heating rates within the regions of separa- tion may be characterized by typical distributions which are essentially inde- pendent of the model geometry (except to the extent that the model-geometry variations affect the location of transition).
    [Show full text]
  • Computational Characterization of Shock Wave
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2018 Computational characterization of shock wave - boundary layer Interactions on flat plates and compression ramps in laminar, hypersonic flow Eli Ray Shellabarger Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Aerospace Engineering Commons Recommended Citation Shellabarger, Eli Ray, "Computational characterization of shock wave - boundary layer Interactions on flat plates and compression ramps in laminar, hypersonic flow" (2018). Graduate Theses and Dissertations. 16465. https://lib.dr.iastate.edu/etd/16465 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Computational characterization of shock wave { boundary layer interactions on flat plates and compression ramps in laminar, hypersonic flow by Eli R. Shellabarger A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Aerospace Engineering Program of Study Committee: Thomas Ward, Major Professor Richard Wlezien Peng Wei The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this thesis. The Graduate College will ensure this thesis is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2018 Copyright c Eli R. Shellabarger, 2018.
    [Show full text]