EXPERIMENTAL APPARATUS AND MODELING FRAMEWORK FOR STUDYING COUNTER-FLOW LAMINAR FLAMES

2019 ◽  
Author(s):  
V. Nevrlý ◽  
V. Klečka ◽  
T. Blejchař ◽  
M. Dostál ◽  
P. Bitala ◽  
...  
Keyword(s):  
Laminar Flames ◽  
Modeling Framework ◽  
Counter Flow ◽  
Experimental Apparatus

The Effect of Lewis Number on Instantaneous Flamelet Speed and Position Statistics in Counter-Flow Flames With Increasing Turbulence

2017 ◽  
Author(s):  
Sean D. Salusbury ◽  
Ehsan Abbasi-Atibeh ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Flame Front ◽  
Turbulence Intensity ◽  
High Speed ◽  
Rayleigh Scattering ◽  
Turbulent Flame ◽  
Lewis Number ◽  
Turbulent Flames ◽  
Flame Speed ◽  
Laminar Flames ◽  
Counter Flow

Differential diffusion effects in premixed combustion are studied in a counter-flow flame experiment for fuel-lean flames of three fuels with different Lewis numbers: methane, propane, and hydrogen. Previous studies of stretched laminar flames show that a maximum reference flame speed is observed for mixtures with Le ≳ 1 at lower flame-stretch values than at extinction, while the reference flame speed for Le ≪ 1 increases until extinction occurs when the flame is constrained by the stagnation point. In this work, counter-flow flame experiments are performed for these same mixtures, building upon the laminar results by using variable high-blockage turbulence-generating plates to generate turbulence intensities from the near-laminar u′/SLo=1 to the maximum u′/SLo achievable for each mixture, on the order of u′/SLo=10. Local, instantaneous reference flamelet speeds within the turbulent flame are extracted from high-speed PIV measurements. Instantaneous flame front positions are measured by Rayleigh scattering. The probability-density functions (PDFs) of instantaneous reference flamelet speeds for the Le ≳ 1 mixtures illustrate that the flamelet speeds are increasing with increasing turbulence intensity. However, at the highest turbulence intensities measured in these experiments, the probability seems to drop off at a velocity that matches experimentally-measured maximum reference flame speeds in previous work. In contrast, in the Le ≪ 1 turbulent flames, the most-probable instantaneous reference flamelet speed increases with increasing turbulence intensity and can, significantly, exceed the maximum reference flame speed measured in counter-flow laminar flames at extinction, with the PDF remaining near symmetric for the highest turbulence intensities. These results are reinforced by instantaneous flame position measurements. Flame-front location PDFs show the most probable flame location is linked both to the bulk flow velocity and to the instantaneous velocity PDFs. Furthermore, hydrogen flame-location PDFs are recognizably skewed upstream as u′/SLo increases, indicating a tendency for the Le ≪ 1 flame brush to propagate farther into the unburned reactants against a steepening average velocity gradient.

An asymptotic analysis for detailed mathematical modeling of counter-flow non-premixed multi-zone laminar flames fueled by lycopodium particles

2019 ◽  
Vol 30 (4) ◽  
pp. 2137-2168 ◽  
Author(s):  
Mehdi Bidabadi ◽  
Sadegh Sadeghi ◽  
Pedram Panahifar ◽  
Davood Toghraie ◽  
Alireza Rahbari
Keyword(s):  
Mathematical Modeling ◽  
Asymptotic Method ◽  
Flame Temperature ◽  
Laminar Flames ◽  
Counter Flow ◽  
Content Type ◽  
Front Position ◽  
Mass Fractions ◽  
Premixed Laminar ◽  
Fuel Particles

Purpose This study aims to present a basic mathematical model for investigating the structure of counter-flow non-premixed laminar flames propagating through uniformly-distributed organic fuel particles considering preheat, drying, vaporization, reaction and oxidizer zones. Design/methodology/approach Lycopodium particles and air are taken as biofuel and oxidizer, respectively. Dimensionalized and non-dimensionalized forms of mass and energy conservation equations are derived for each zone taking into account proper boundary and jump conditions. Subsequently, to solve the governing equations, an asymptotic method is used. For validation purpose, results achieved from the present analysis are compared with reliable data reported in the literature under certain conditions. Findings With regard to the comparisons, although different complex non-homogeneous differential equations are solved in this paper, acceptable agreements are observed. Finally, the impacts of significant parameters including fuel and oxidizer Lewis numbers, equivalence ratio, mass particle concentration, fuel and oxidizer mass fractions and lycopodium initial temperature on the flame temperature, flame front position and flow strain rate are elaborately explained. Originality/value An asymptotic method for mathematical modeling of counter-flow non-premixed multi-zone laminar flames propagating through lycopodium particles.

70. A Full-Scale Experimental Apparatus to Study MDR-TB Transmission

2006 ◽  
Author(s):  
S. Parsons ◽  
P. Jensen ◽  
C. Wells ◽  
M. First ◽  
E. Nardell ◽  
...  
Keyword(s):  
Full Scale ◽  
Experimental Apparatus ◽  
Mdr Tb

DYNAMICS OF COUNTER-FLOW INJECTION FOR WAVE DRAG REDUCTION

2018 ◽  
Author(s):  
Vishnu Prakash K ◽  
Siddesh Desai ◽  
Hrishikesh Gadgil ◽  
Vinayak Kulkarni
Keyword(s):  
Drag Reduction ◽  
Flow Injection ◽  
Wave Drag ◽  
Counter Flow ◽  
Wave Drag Reduction

PERFORMANCE ANALYSIS OF DOUBLE PASS COUNTER FLOW SOLAR AIR HEATER FOR DRYING APPLICATION

2018 ◽  
Author(s):  
D.V.N. Lakshmi ◽  
Palanisamy Muthukumar ◽  
Dr.Apurba Layek ◽  
Abhimanyu Kumar Singh ◽  
Sushoban Das
Keyword(s):  
Performance Analysis ◽  
Solar Air Heater ◽  
Double Pass ◽  
Counter Flow ◽  
Air Heater

PERFORMANCE ANALYSIS OF MICROCHANNEL COUNTER FLOW HEAT EXCHANGER USING DIFFERENT NANOFLUIDS

2018 ◽  
Author(s):  
Bharath P ◽  
Doddamani Hithaish ◽  
Saravanan Venkatesh ◽  
C K Umesh
Keyword(s):  
Heat Exchanger ◽  
Performance Analysis ◽  
Counter Flow ◽  
Flow Heat
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