Application of a multiple mapping conditioning mixing model to ECN Spray A
| Autor: | Evatt R. Hawkes, Matthew J. Cleary, Gianluca D'Errico, Qing Nian Chan, Sanghoon Kook, Achinta Varna, Armin Wehrfritz, Tommaso Lucchini |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Correlation coefficient 020209 energy General Chemical Engineering Mixing model Combustion Thermodynamics Probability density function 02 engineering and technology Space (mathematics) 01 natural sciences 010305 fluids & plasmas ECN MMC TPDF Reference variable 0103 physical sciences 0202 electrical engineering electronic engineering information engineering Physical and Theoretical Chemistry Mixing (physics) Mechanical Engineering 13. Climate action Conditioning Constant (mathematics) |
| Zdroj: | Proceedings of the Combustion Institute. 37:3263-3270 |
| ISSN: | 1540-7489 |
| Popis: | The engine combustion network (ECN) Spray A is modelled using the Reynolds-averaged Navier–Stokes-transported probability density function (RANS-TPDF) approach to validate the application of a new multiple mapping conditioning (MMC) mixing model to multiphase reactive flows. The composition TPDF equations are solved using a Lagrangian stochastic approach and the spray is modelled with a discrete particle approach. The model is first validated under non-reacting conditions (at 900 K) using experimental mixture-fraction data. Reactive simulations are then performed for three different ambient temperatures (800, 900, 1100 K) and oxygen concentrations (13, 15, 21%) at an ambient density of 22.8 kg/m3. The MMC mixing model is compared with the interaction by exchange with the mean (IEM) mixing model. The ignition delay predictions are not sensitive to the mixing model and are predicted well by both the mixing models under all the tested ambient conditions. The IEM model overpredicts the flame lift-off length (FLOL) at high temperature and high oxygen conditions with a mixing constant C ϕ = 2 . The MMC model with C ϕ = 2 and a target correlation coefficient r t = 0.935 between the mixture fraction and a reference variable used to condition mixing predicts good FLOL under all the conditions except 800 K. It is demonstrated that the lift-off length is controllable by changing the target correlation coefficient, while Cϕ and therefore the mixing fields are held fixed. In comparison to the MMC model, the IEM model predicts a higher variance of temperature conditioned on mixture fraction near the flame base owing to its lacking the property of localness. The mixing distance between the notional TPDF particles in the composition space is also higher with the IEM model and it is demonstrated that by changing rt, different levels of mixing locality can be achieved. |
| Databáze: | OpenAIRE |
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