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EFC Topic 4.3 Benchmarking : comparisons, analysis, and validation

EFC Topic 4.3 Benchmarking : comparisons, analysis, and validation . Objectives Topic 4.3 Exposition of methods & metrics being used to assess simulation equivalency & efficacy of measured flow & combustion. Define ECN 3.X Topics, 2014-2015 - Identify what is needed.

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EFC Topic 4.3 Benchmarking : comparisons, analysis, and validation

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  1. EFC Topic 4.3 Benchmarking: comparisons, analysis, and validation Objectives Topic 4.3 Exposition of methods & metrics being used to assess simulation equivalency & efficacy of measured flow & combustion Define ECN 3.X Topics, 2014-2015 - Identify what is needed. - Identify action.

  2. EFC Topic 4.3 Benchmarking: comparisons, analysis, and validation Presented by Dave Reuss • Sources of contributions to EFC: • Tech. Univ. Darmstadt; Brian Peterson, peterson@csi.tu-darmstadt.de • IFP EnergieNouvelles; Cecile Pera, cecile.pera@ifpen.fr • Penn. State Univ; Dan Haworth, dch12@engr.psu.edu • Univ. Michigan;David Reuss, dreuss@umich.edu, Volker Sick, vsick@umich.edu • Politecnicodi Milano; TommasoLucchini, tommaso.lucchini@polimi.it • Univ. Duisburg-Essen; Sebastian Kaiser, sebastian.kaiser@uni-due.de • General Motors R&D; Xiaofeng Yang, xiaofeng.yang@gm.com, • Tang-Wei Kuo, tang-wei.kuo@gm.com

  3. 4.3. Benchmarking: comparisons, analysis, and validation 4.3.1. Global engine operating conditions 4.3.2. In-cylinder flow characterization 4.3.3. Simulated to measured combustion modeling validation Ultimately, all detailed (small time and space scale) simulation quantities must predict volume-average/global measure (work and engine-out emissions) Rational flow CCV metrics require knowledge of what flow parameters best correlate with fuel-mixing and combustion CCV ECN 3.X 2014-2015 Efforts: Interdependency requires parallel efforts.

  4. 4.3.1. Global Engine Metrics

  5. 4.3.1. Global engine operating conditions 4.3.1.1.In-cylinder 0-D & Global Metrics ECN 3.X Topic option: Document precision & accuracy for mechanical & pressure test-to-test & CCV. Location Peak Pressure P_cyl Pegging TCC-III

  6. 4.3.1. Global engine operating conditions 4.3.1.1.In-cylinder 0-D & Global Metrics KE @ Field of View TCC Milano ECN 3.X Topic option: - Identify useful volume- & plane-averaged metrics. - Quantify flow metrics & values for simulation effectiveness.

  7. 4.3.1.2. Intake & Exhaust Systems 1-D quantities PIntakePort Discrepancy, (simulation – measurement) Discrepancy, % CoV, % Measurement Noise   LES CCV ECN 3.X Topic options: - Quantify effect of P_Intk_PortCCV on trapped mass & flow. - Quantify simulationnoise precision and accuracy. TCC-III

  8. 4.3.1. Global engine operating conditions 4.3.1.2. Intake & Exhaust Systems 1-D quantities -200 CAD PIV: 200 cycles INTAKE ECN 3.X Topic options: - Quantify impact of intake-port 1-D pressure & 3-D velocity on in-cylinder CCV. Trapped Mass • LES: 25 cycles Mean Pintake Intake pipe velocity [m/s] • SGEmac

  9. 4.3.2. In-cylinder flow characterization

  10. 4.3.2. Simulated-to-Measured Flow characterization • 4.3.2.1. Statistical Methods • SGEmac • next step • Resolution dependence • Model dependences • SIDI TUD PDF ECN 3.X Topic option: Identify methods and metrics to quantitatively assess equivalency of simulated & measured velocity and momentum dissipation.

  11. 4.3.2. Simulated-to-Measured Flow characterization 4.3.2.1.Statistical Methods 4.3.2.1.1. phase-average and standard deviation LES Ens. Ave. Measured Ens. Ave Ens,. Std. Dev. • SIDI TUD Ensemble Average & Standard Deviation (CCV) of PIV & LES velocity are equivalent metrics. ECN 3.X Topic option: Identify rational measurements to characterize RANS “turbulence” TCC, RANS

  12. 4.3.2. Simulated-to-Measured Flow characterization 4.3.2.1.Statistical Methods 4.3.2.1.2. CCV vs. turbulence vs. noise PIV dynamic range  Max velocity  Velocity noise Simulation Noise ? PIV interrogation % first choices PIV interrogation quality Crankangle ECN 3.X Topic option: - Standards exist to quantify measurement noise. - How are simulation noise & uncertainty quantified?

  13. 4.3.2. Simulated-to-Measured Flow characterization 4.3.2.2.Proper Orthogonal Decomposition, Phase-dependent POD • Snapshots sampled @ one CA, all cycles • POD creates multi-dimensional “empirical” basis functions. • Modes created based on flow • high KE (V2, or I2) • and/or repeatable. - Eigen values capture KE. - Can be used for CCV of Modes Mode 1 mid intake stroke KE, m2/s2 TCC- I cycle #

  14. 4.3.2.2.Proper Orthogonal Decomposition, Phase-invariant POD • Velocity snapshots • sampled @ all CA, all cycles • mapped to single grid • normalized to KE of individual snapshot • POD creates single set of modes applicable to • all CA, • all cycles. • Normalized KE creates modes based on • normalized velocity and • intra-cycle persistence (cycle similarity) Mode 1 Mode 2 Eigenvalue captures intra-cycle variability  flow similarity  CCV Coefficients TCC crank angle

  15. 4.3.2. Simulated-to-Measured Flow characterization Combine Measured & LES snapshots + Phase-invariant POD  single set of POD Modes. Coefficients provide metric for direct comparison of measured vs simulated Intra-cycle and Inter-cycle equivalence. LES PIV Coefficients crank angle ECN 3.X Topic option: POD is not universally or extensively used as a metric. Identify acceptable methods and standards of POD application.

  16. 4.3.2. Simulated-to-Measured Flow characterization 4.3.2.8. Simulation efficacy of scalar mixing. Experiment Simulation End of hydrogen injection ECN 3.X Topic option: Efficacy of simulations on one- & two-phase mixing, especially sub-grid. H2 mole fraction • H2ICE

  17. 4.3.3. Combustion-Modeling validation

  18. 4.3.3. Combustion modeling validation 4.3.3.1. Global heat release I • SGEmac • ECN 3.X Topic option: • Create defined methods for computing work (IMEP) and Apparent Heat Release, AHR. • Establish standard of accepted equivalence between measured and simulated AHR.

  19. 4.3.2. Combustion modeling validation 4.3.3.2. Ignition and early flame development. Single-cycle Mie-scattering OH PLIF, probability of flame Chemiluminescence, Single cycle PDF of burn-gas  PDF of burned gas 2-D plane  PDF of burned gas 3-D projection • SIDI TUD • SGEmac

  20. 4.3.2. Combustion modeling validation 4.3.3.2. Ignition and early flame development. • SIDI TUD 0.20 0.15 0.10 0.05 0.00 PDF (ST) ECN 3.X Topic option: Identify optical metrics applicable to both measured & simulated data to define equivalency during early burning ( burned mass fraction < 20%). -5 0 5 10 15 ST (m/s)

  21. 4.3.2. Combustion modeling validation 4.3.3.2. Fully Developed turbulent flame • Turbulent-combustion of late-burned mass • Compressed scales • Dissipation • Near-wall • Poor optical access • (esp. SC SIDI with a bowl) ECN 3.X Topic option: What is needed? What experiments are possible ?

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