Dynamics and Structure of Dusty Reacting Flows: Inert Particles in Strained, Laminar, Premixed Flames
نویسندگان
چکیده
A detailed numerical study was conducted on the dynamics and thermal response of inert, spherical particles in strained, laminar, premixed hydrogen/air flames. The modeling included the solution of the steady conservation equations for both the gas and particle phases along and around the stagnation streamline of an opposed-jet configuration, and the use of detailed descriptions of chemical kinetics and molecular transport. For the gas phase, the equations of mass, momentum, energy, and species are considered, while for the particle phase, the model is based on conservation equations of the particle momentum balance in the axial and radial direction, the particle number density, and the particle thermal energy equation. The particle momentum equation includes the forces as induced by drag, thermophoresis, and gravity. The particle thermal energy equation includes the convective/conductive heat exchange between the two phases, as well as radiation emission and absorption by the particle. A one-point continuation method is also included in the code that allows for the description of turning points, typical of ignition and extinction behavior. As expected, results showed that the particle velocity can be substantially different than the gas phase velocity, especially in the presence of large temperature gradients and large strain rates. Large particles were also found to cross the gas stagnation plane, stagnate, and eventually reverse as a result of the opposing gas phase velocity. It was also shown that the particle number density varies substantially throughout the flowfield, as a result of the straining of the flow and the thermal expansion. Finally, for increased values of the particle number density, substantial flame cooling to extinction states and modification of the gas phase fluid mechanics were observed. As also expected, the effect of gravity was shown to be important for low convective velocities and heavy particles. Under such conditions, simulations indicate that the magnitude and direction of the gravitational force can substantially affect the profiles of the particle velocity, number density, mass flux, and temperature. © 1999 by The Combustion Institute
منابع مشابه
Effects of Combustible Dust Clouds on the Extinction Behavior of Strained, Laminar Premixed Flames in Normal Gravity
An experimental and numerical study was performed on the interaction of combustible solid particles with atmospheric, strained, laminar premixed methane/air and propane/air flames in normal gravity. The study was conducted in the opposed-jet configuration in which a single flame was stabilized below the gas stagnation plane by counterflowing a mixture against an air jet. Into the flame were see...
متن کاملSynthesis of TiO2 nanoparticles by premixed stagnation swirl flames
A new turbulent, premixed, stagnation swirl flame (SSF) is used to synthesize titanium dioxide (TiO2) nanopowders. Synthesis conditions under two flame modes, i.e., burnerand substrate-stabilized SSF, are investigated, for the same equivalence ratio, but different inert-dilution ratios. The particles (collected on the substrate) have high anatase purity, with mean diameters of 5–10 nm, determin...
متن کاملNumerical Simulation of Laminar Reacting Flows with Complex Chemistry
We present an adaptive algorithm for low Mach number reacting flows with complex chemistry. Our approach uses a form of the low Mach number equations that discretely conserves both mass and energy. The discretization methodology is based on a robust projection formulation that accommodates large density contrasts. The algorithm uses an operator-split treatment of stiff reaction terms and includ...
متن کاملOn the Coupling Between Length and Time Scales in Reactive Flows
We discuss one-dimensional steady laminar premixed flames in a mixture of calorically imperfect ideal gases described by detailed kinetics and multi-component transport. The required spatial discretization to capture all detailed continuum physics in the reaction zone is determined a posteriori and estimated a priori. Application of the method to laminar premixed flames in several mixtures over...
متن کاملParticle streak velocimetry and CH laser-induced fluorescence diagnostics in strained, premixed, methane-air flames
We present the use of simultaneous Particle Streak Velocimetry (PSV) and CH Planar Laser Induced Fluorescence (PLIF) diagnostics in the study of planar, strained, premixed, methane-air flames, stabilized in a jet-wall stagnation flow. Both PSV and PLIF data are imaged at high spatial resolution and sufficiently high framing rates to permit an assessment of flame planarity and stability. Concurr...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1998