ICE Roadmap Japanese STAR Conference Richard Johns Introduction - - PowerPoint PPT Presentation

ICE Roadmap Japanese STAR Conference

Richard Johns

Introduction

• Top-Level Roadmap
• STAR-CCM+ and Internal Combustion Engines
• Modeling Improvements and Research Support
• Sprays
• LES
• Chemistry
• Meshing
• Summary

Top-Level Roadmap for In-Cylinder CFD

STAR STAR-CD CD STAR STAR-CCM CCM+

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Advantage of a Integrated STAR-CCM+ Solution

In In-Cylinder Cylinder Fuel el Inje ject ction ion and d Fuel el Sy System tem Superc ercharg harging ing Engine ine CHT T & St Struc uctural ural Analysis lysis Pis iston n undercrown dercrown cooling

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Cran ankcase/ kcase/oil

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lash/ h/ bear arings/br ings/breather eather sys ystem em Intak ake/ e/Ex Exhaust haust System ems 1D 1D-3D coup upling ling Af Aftertreatm rtreatmen ent Optim imization ization

The Development and Adoption of Mathematical Models

• CD-adapco does not choose to be an “Inventor of Models””
• We see our tasks as:
• Model adopter
• Implementation - Refinement, Generalization and

Industrialization

• Validation
• Development of Recommended Usage & Best

Practices

• Dissemination
• Benchmarking
• Support
• Further refinement in the light of experience

Engineering-Level vs High Fidelity Models

Hig igh-Fidelit Fidelity y spr pray ay-break reakup up model

• del

Engineering ineering-Le Level vel spr pray ay-break breakup up model del

• Why do we support High-Fidelity Models?
• We learn a lot about fundamental physics
• If we can’t solve the problem in a HF model we certainly

won’t solve it in a EL model

• Our objective is to deliver both HF and EL models

University Research & “Research Clubs”

• We actively support and fund a number of universities

around the world where there are strong ICE Research groups

• We support and engage with many others – the following

slides are not a comprehensive list – just a brief summary

• We also members of and/or participate in various research

“clubs”:

• FVV, Germany
• Support of industry-initiated university projects
• DERC – Direct-Injection Engine Research Consortium
• Univ of Wisconsin research club focused on

experimental and theoretical ICE fundamentals

University Research

University of Modena, Italy Principal Investigator: Prof S Fontanesi Development and Application of LES and improved RANS models for flow, mixture distribution and knock University of Connecticut, US Principal Investigators: Professors Tianfeng Lu and Zhuyin Ren Chemistry mechanisms, solver speedup, reduced mechanisms, and mechanism reduction tools

University Research

Penn State University, US Principal Investigator: Prof D Haworth Validation of in-cylinder Flow and Turbulence with experimental data, soot model development Doshisha University, Japan, Principal Investigator: Prof Senda Spray-Wall impingement modeling. fuel injection, spray heat & mass transfer, flash boiling

University Research

University of Darmstadt, Germany Principal Investigator: Prof Janicka Validation of Flow and Turbulence with in-cylinder measurements Un Universi sity ty of Vien Vienna Principal Investigator: Prof Lauer Modeling of multicomponent fuels, wall effects, autoignition in gasoline engines

University Research

Seoul National University (SNUAL) Principal Investigator: Prof Min Combustion and emissions modeling: flamelets, dual-fuel, level-set, knock ETH Zurich (Technical University) Principal Investigator: Dr Yuri Wright Combustion and emissions modeling: CMC, level-set, fuels, LES and DES in-cylinder flows

Pamb mb = 1 120 0 kPa Pamb mb = 4 40 kPa Pin inj = 2 20 Mpa Tin inj = 100 0 C

Ref: Parrish ish & Zink, , GM R R&D, Ilass 2008 2008

• Current injection systems and operating conditions can

lead to complex spray phenomena

Fuel Injection and Sprays

Non-flashing vs flashing analysis

Non-flas lashing hing Fla lash shing ing Y is is th the mass ss frac action ion of n non-conde condensib nsible le gas as

Courtesy of Prof David Schmidt, University of Massachusetts

Pintle nozzle – jet-string breakup

Pin intle le Noz

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zle

LES/VOF calculation of jet-string breakup

ATOMIC 5 deg sector

Spray Modeling Strategy

• Support of HF and EL projects to understand better and improve

physics modeling

• Develop numerical and meshing technologies to support new

Engineering Level models that can be embodied into in-cylinder calculations

In-Cylinder LES, mixture formation and Cyclic Variability

• Ensemble or cycle-averaged CFD and measurements are an

approximation to reality

• Small-scale information lost in the averaging process

In-Cylinder LES, mixture formation and Cyclic Variability

LES – Intake take Flow low Struct ructure ure

Cy Cycled led-Averag veraged ed LES

LES – multicycle flame development

LES - 3D Results Insight:

Prediction of COV

In-Cylinder LES, mixture formation and Cyclic Variability

• The Challenges:
• Can we predict this successfully using High-Fidelity

modeling?

• Can we derive an Engineering-Level model from the lessons

learned from a High-Fidelity model?

• Are these modeling additions to our code or different ways of

processing existing solutions?

• Are there other flow features, such as instabilities, that we

ignore at our peril?

• Is there a first-mover advantage for an OEM in being an early-

adopter of high-end technology?

Combustion Chemistry

• Strengthened Team:
• Graham Goldin
• Karin Fröjd
• DARS v2.10 release:
• ECFM and PVM library generation incl dual-fuel
• Extended Range Soot library
• University Collaborations
• Complex fuel chemistry (DME, biodiesel etc)
• Soot modeling
• Dual Fuel

Meshing Technology

• Meshing is important!
• Automatic
• Efficiency & consistency in a production environment
• Optimization and automated shape-change
• Accurate
• The ability to capture boundary details and small-scale

phenomena and gradients, for example, sprays, spark ignition etc

• Robust & Fast
• Must be successful 99% of the time and add minimal
• verhead

Meshing Technology

• We have/will have 3 meshing options:

1) Existing template/trimmed meshing

– es-ice today, being developed for STAR-CCM+

2) XMesher

–

based on multiple morphed meshes and solution mapping – STAR-CD and STAR-CCM+

3) Overset Mesh

– “Attachment” of individual meshes to components moving through a stationary background mesh

– STAR-CCM+ only

Overset Mesh

XMesher – Automated Meshing for ICE

• Developed over the past ~3 years
• Stage 1:
• Fully automatic, full-cycle meshing
• Tested successfully on ~30 different real engine cases
• Close comparison of results with es-ice meshing
• Will be released in 2015
• Stage 2
• Local mesh refinement linked to specific events
• Embedded spray-adapted meshing

XMesher Solution Strategy

Mesh generated at this time Mesh morphed in - time Mesh morphed in + time Solution mapped to next mesh

Constrained Polyhedra Core Cartesian Mesh Prism Layers Aligned valve-seat mesh

Solution Mapping Solution Continues Morphing

XMesher

Illustration of XMesher process

Initial Meshes are inserted automatically

Meshes are morphed with piston and valve motions, tested and then additional meshes inserted as required

Illustration of XMesher process

This cycle is repeated until meshes for the entire calculation have been generated.

Illustration of XMesher process

Performance

• Concurrent meshing/morphing is used. Typical

total time ~ ½ to 1 hour

2 4 8 # cores res 30 30 60 60 90 90 Tim ime (mins mins)

Summary of Test Cases

Case Total Mesh Generation time (mins) Number

• f Grids

Base Mesh (mm) Max No. of cells Min No.

• f cells

#1 2v gasoline 22 19 1 666945 498419 #2 4v gasoline 33 20 2 691707 485946 #3 4v diesel 60 23 2 1994121 1397606 #4 4v gasoline 42 16 1 751447 538127 #5 4v gasoline 37 17 2 1473225 777593 #6 4v gasoline 30 18 1 895494 720668

+24 Furt rthe her r Ca Cases

Cell Count through an engine cycle

1.5M 1.2M

Vector Field

XMesher – Stage 2

• Objective is:
• Physics-dependent local refinement
• General spray-oriented meshing, including the possibility

if meshing inside the injector if required

• In prototype stage now

Physics-driven Locally-refined meshing

Physics-driven Locally-refined meshing

General Spray-Adapted Mesh

General Spray-Adapted Mesh

Summary

• Major Commitment to developing a STAR-CCM+ ICE Solution
• Continued Support for STAR-CD for as long as required by our

Customers – v4.24 in 2015

• New automated accurate meshing coming in both STAR-CD

and STAR-CCM+

• Focused physics research leading to an improved predictive

capability in key areas

• Continued Support to deliver Best-in-Class Engineering

Solutions for ICE of all our Customers