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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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slide1

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.

slide2

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
slide3

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.

slide5

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

slide6

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.

slide7

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

slide8

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
slide10

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.

slide11

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

slide12

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?

slide13

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 #

slide14

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

slide15

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.

slide16

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
slide18

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.
slide19

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
slide20

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)

slide21

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 ?