Frankel, SH
1993
Binary Scalar Mixing and Reaction in Homogeneous Turbulence: Some Linear Eddy Model Results
Frankel, S.H.; Madnia, C.K.; McMurtry, P.A. and Givi, P.
Energy & Fuels, 7 (6):827-834, 1993. Funded by National Science Foundation, Office of Naval Research, and ACERC.
The Linear Eddy Model (LEM) of Kerstine is used to simulate the mechanism of scalar mixing from an initial binary state in incompressible, homogeneous turbulence. The simulated results are used to measure the limiting rate of mean reactant conversion in a chemical reaction of the type F + rO --> (1 + r) Products under isothermal and nonpremixed conditions. The objective of the simulations is to access the performance of the closed form analytical expressions obtained by Madnia et al., based on the Amplitude Mapping Closure for the evaluation of the mean reactant conversion rate. This assessment is made for various flow conditions with different asymptotic statistical behavior.
Linear Eddy Modeling of Reactant Conversion and Selectivity in Turbulent Flows
Frankel, S.H.; McMurtry, P.A. and Givi, P.
Presented at the APS Division of Fluid Dynamics Conference, Albuquerque, NM, November 1993. Funded by the National Science Foundation and ACERC.
The Linear Eddy Model (LEM) is utilized for statistical predictions of stationary, homogeneous turbulent flows under the influence of isothermal chemical reactions. Nonpremixed reacting systems are considered with two reaction mechanisms: A binary, irreversible single-step reaction of the type A + B --> P, and the series-parallel reaction A + B --> R, A + R --> P. For both systems, the influence of various flow parameters on the rate of reactant conversion is elucidated. For the second reaction scheme, the effects of the flow parameters on the "selectivity" are also investigated. The trends portrayed by LEM are shown to be in accord with those produced by Direct Numerical Simulation (DNS) at moderate values of the Reynolds number, the Schmidt number and the Damköhler number. The advantage of LEM is its capability to extend the parameter range well beyond that currently attainable by DNS. The LEM generated results for a wide range of Schmidt and Damköhler numbers are presented and their effects on the chemical selectivity are discussed. These results are also used to examine the performance of some of the existing closures for the modeling of selectivity. It is shown that none of the closures considered are capable of reproducing LEM results accurately. In view of the agreement of LEM predictions with DNS results and the previous success of the model in reproducing known statistical features of scalar mixing, the use of the model is recommended for statistical modeling and analyses of chemically reacting turbulent flows.
Frankel, SH
1993
Binary Scalar Mixing and Reaction in Homogeneous Turbulence: Some Linear Eddy Model Results
Frankel, S.H.; Madnia, C.K.; McMurtry, P.A. and Givi, P.
Energy & Fuels, 7 (6):827-834, 1993. Funded by National Science Foundation, Office of Naval Research, and ACERC.
The Linear Eddy Model (LEM) of Kerstine is used to simulate the mechanism of scalar mixing from an initial binary state in incompressible, homogeneous turbulence. The simulated results are used to measure the limiting rate of mean reactant conversion in a chemical reaction of the type F + rO --> (1 + r) Products under isothermal and nonpremixed conditions. The objective of the simulations is to access the performance of the closed form analytical expressions obtained by Madnia et al., based on the Amplitude Mapping Closure for the evaluation of the mean reactant conversion rate. This assessment is made for various flow conditions with different asymptotic statistical behavior.
Linear Eddy Modeling of Reactant Conversion and Selectivity in Turbulent Flows
Frankel, S.H.; McMurtry, P.A. and Givi, P.
Presented at the APS Division of Fluid Dynamics Conference, Albuquerque, NM, November 1993. Funded by the National Science Foundation and ACERC.
The Linear Eddy Model (LEM) is utilized for statistical predictions of stationary, homogeneous turbulent flows under the influence of isothermal chemical reactions. Nonpremixed reacting systems are considered with two reaction mechanisms: A binary, irreversible single-step reaction of the type A + B --> P, and the series-parallel reaction A + B --> R, A + R --> P. For both systems, the influence of various flow parameters on the rate of reactant conversion is elucidated. For the second reaction scheme, the effects of the flow parameters on the "selectivity" are also investigated. The trends portrayed by LEM are shown to be in accord with those produced by Direct Numerical Simulation (DNS) at moderate values of the Reynolds number, the Schmidt number and the Damköhler number. The advantage of LEM is its capability to extend the parameter range well beyond that currently attainable by DNS. The LEM generated results for a wide range of Schmidt and Damköhler numbers are presented and their effects on the chemical selectivity are discussed. These results are also used to examine the performance of some of the existing closures for the modeling of selectivity. It is shown that none of the closures considered are capable of reproducing LEM results accurately. In view of the agreement of LEM predictions with DNS results and the previous success of the model in reproducing known statistical features of scalar mixing, the use of the model is recommended for statistical modeling and analyses of chemically reacting turbulent flows.