DESIGN OF A FUEL-EFFICIENT TWO-STROKE DIESEL ENGINE FOR MEDIUM - - PowerPoint PPT Presentation

▶
design of a fuel efficient two stroke diesel
SMART_READER_LITE
LIVE PREVIEW

DESIGN OF A FUEL-EFFICIENT TWO-STROKE DIESEL ENGINE FOR MEDIUM - - PowerPoint PPT Presentation

Nov 13, 2023 315 likes •614 views

DESIGN OF A FUEL-EFFICIENT TWO-STROKE DIESEL ENGINE FOR MEDIUM PASSENGER CARS: COMPARISON BETWEEN STANDARD AND REVERSE UNIFLOW SCAVENGING ARCHITECTURES Galpin, J., Colliou, T., Laget, O., Rabeau, F., De Paola, G. IFP Energies nouvelles,

slide-1
SLIDE 1

DESIGN OF A FUEL-EFFICIENT TWO-STROKE DIESEL ENGINE FOR MEDIUM PASSENGER CARS: COMPARISON BETWEEN STANDARD AND REVERSE UNIFLOW SCAVENGING ARCHITECTURES

Galpin, J., Colliou, T., Laget, O., Rabeau, F., De Paola, G. IFP Energies nouvelles, Institut Carnot IFPEN TE Rahir, P. Groupe Renault

slide-2
SLIDE 2

SAE INTERNATIONAL

1. INTRODUCTION

  • CONTEXT
  • OVERVIEW OF SCAVENGING ARCHITECTURES
  • BENCHMARK OF SCAVENGING CONFIGURATIONS

2. SYSTEM SIMULATION ANALYSIS

  • INTRODUCTION
  • SIMULATION METHODOLOGY
  • RESULTS
  • CONCLUSIONS

3. 3D CFD ANALYSIS

  • INTRODUCTION
  • SIMULATIONS DETAILS
  • QUALITATIVE RESULTS
  • QUANTITATIVE RESULTS

4. MAIN CONCLUSIONS & PERSPECTIVES

CONTENT

Paper 2017-01-0645 2

slide-3
SLIDE 3

SAE INTERNATIONAL

1. INTRODUCTION

  • CONTEXT
  • OVERVIEW OF SCAVENGING ARCHITECTURES
  • BENCHMARK OF SCAVENGING CONFIGURATIONS

2. SYSTEM SIMULATION ANALYSIS

  • INTRODUCTION
  • SIMULATION METHODOLOGY
  • RESULTS
  • CONCLUSIONS

3. 3D CFD ANALYSIS

  • INTRODUCTION
  • SIMULATIONS DETAILS
  • QUALITATIVE RESULTS
  • QUANTITATIVE RESULTS

4. MAIN CONCLUSIONS & PERSPECTIVES

Paper 2017-01-0645 3

slide-4
SLIDE 4

SAE INTERNATIONAL

REWARD project

  • REal World Advanced Technologies foR Diesel Engine
  • H2020 project funded by the European Union
  • A consortium formed by European industries, R&I providers and Universities
  • Improving Diesel engine efficiency
  • Main targets

– ≥ 5% improved fuel economy – ≥ 3 dB less noise – ≥ 50% less particles emission – Compliance with post Euro 6 limits under Real Driving conditions

Development a fuel efficient 2-stroke Diesel engine

  • Target = Medium / class C vehicles
  • Partners = Groupe Renault, CMT-Universitat Politècnica de València, Czech

Technical univ., AVL, Delphi and IFP Energies Nouvelles

INTRODUCTION

CONTEXT

Paper 2017-01-0645 4

slide-5
SLIDE 5

SAE INTERNATIONAL

Diesel engine market for automotive applications = 4-stroke But a renewed interest of 2-stroke Diesel engines

  • Larger power density
  • Reduction of the number of cylinders

– Compactness – Weight reduction thus potential cost reduction

  • Natural operation with IGR  NOx in transient (no EGR latency)

Key point is scavenging

  • Combustion each revolution  small time devoted to gases transfers
  • Scavenging = quasi overlapping of the intake & exhaust
  • Targeted features

– Trap fresh gases as much as possible – Short-circuiting as low as possible

Paper 2017-01-0645 5

INTRODUCTION

CONTEXT

slide-6
SLIDE 6

SAE INTERNATIONAL

Type Outline Advantages Drawbacks

Transfer ports only

  • No camshaft
  • Low friction
  • Simplicity
  • Large ports permeability
  • Long piston skirt / deflector
  • Fixed intake/ exhaust timings

and diagrams

  • Short-circuiting

Poppet valves only

  • Mechanical layout close to

conventional 4-stroke engine

  • No lubrication issue
  • VVT possible
  • No swirl motion generated
  • Low permeability of valves

Poppet valves and transfer ports

  • Efficient scavenging 

limited short circuiting

  • More efficient architecture

compared to Poppet valves according to Abthoff et al.

  • VVT only for the valves

6

00

INTRODUCTION

OVERVIEW OF SCAVENGING ARCHITECTURES

slide-7
SLIDE 7

SAE INTERNATIONAL

First step of the project = Standard or Reverse uniflow ? Question 1 = Shorten expansion or shorten compression ?

  • No flexibility on the ports diagram

– No flexibility on the transfer ports diagram – Symmetric diagram centered around BDC – Exhaust occurs earlier than intake

  • System code simulations

– LMS Imagine.Lab Amesim code – Several intake & exhaust diagrams investigated

Paper 2017-01-0645 7

Standard uniflow = shorten expansion

Standard uniflow Intake by ports Exhaust by valves Reverse uniflow Intake by valves Exhaust by ports

Reverse uniflow = shorten compression

INTRODUCTION

BENCHMARK OF SCAVENGING CONFIGURATIONS

slide-8
SLIDE 8

SAE INTERNATIONAL

First step of the project = Standard or Reverse uniflow ? Question 2 = Which conf. provides the most efficient scavenging ?

  • Geometries upstream the cylinder differs strongly

between both configurations

  • Effects on the scavenging ?
  • 3D CFD simulations

– CONVERGE CFD 2.2 – Several geometries tested

Paper 2017-01-0645 8

Standard uniflow Intake by ports Exhaust by valves Reverse uniflow Intake by valves Exhaust by ports

Standard uniflow Reverse uniflow

INTRODUCTION

BENCHMARK OF SCAVENGING CONFIGURATIONS

slide-9
SLIDE 9

SAE INTERNATIONAL

1. INTRODUCTION

  • CONTEXT
  • OVERVIEW OF SCAVENGING ARCHITECTURES
  • BENCHMARK OF SCAVENGING CONFIGURATIONS

2. SYSTEM SIMULATION ANALYSIS

  • INTRODUCTION
  • SIMULATION METHODOLOGY
  • RESULTS
  • CONCLUSIONS

3. 3D CFD ANALYSIS

  • INTRODUCTION
  • SIMULATIONS DETAILS
  • QUALITATIVE RESULTS
  • QUANTITATIVE RESULTS

4. MAIN CONCLUSIONS & PERSPECTIVES

Paper 2017-01-0645 9

slide-10
SLIDE 10

SAE INTERNATIONAL

Purpose

  • Benchmark between standard and reverse uniflow on 3 operating points

– 3000rpm x 11bar (FL) – 2000rpm x 7bar – 1500rpm x 4bar

  • Comparison based on Fuel consumption
  • No assessment of the emissions

Engine configuration

  • Based on a Renault K9K engine

– 4-stroke – 4 cylinders 1,460cm3

  • and adapted to the study

– SCE – Supercharger added

Paper 2017-01-0645 10

SYSTEM SIMULATION ANALYSIS

INTRODUCTION Type Outline

Displaced volume 400 cm3 Stroke 76 mm Bore 88 mm Connecting Rod 180 mm Geometrical compression ratio 16.0 Numbers of valves / ports 4 / 12 Supercharging Turbocharger and supercharger

slide-11
SLIDE 11

SAE INTERNATIONAL

Fixed parameters

  • Pintake-Pexhaust fixed per operating point
  • Combustion law

– Dual Flame Model (IFP drive lib.) – CA50 = 10 CAD after TDC

  • Fixed turbocharger and mechanical

compressor efficiencies

  • Scavenging curve (hypothesis)

Paper 2017-01-0645 11

In-cylinder burnt gases fraction Burnt gases fraction in the exhaust

Perfect scavenging

  • All in-cylinder burnt gases have been removed
  • No by-pass of fresh gases

Perfect short-circuiting

  • Full by-pass of fresh gases
  • No removal of in-cylinder

burnt gases

SYSTEM SIMULATION ANALYSIS

SIMULATION METHODOLOGY

slide-12
SLIDE 12

SAE INTERNATIONAL

Variable parameters

  • Several combinations intake/exhaust diagrams investigated
  • Intake pressure Pintake (Pintake-Pexhaust is kept fixed)

Paper 2017-01-0645 12

Reverse uniflow Standard uniflow

SYSTEM SIMULATION ANALYSIS

SIMULATION METHODOLOGY

slide-13
SLIDE 13

SAE INTERNATIONAL

Corrected ISFC

  • ISFC + penalty due to the supercharger work
  • Most promising combinations intake/exhaust diagrams plotted
  • Corrected ISFC  when Pintake  due to the supercharger
  • 10g/kWh benefit for the reverse configuration
  • Large ISFC  pre-design study, optimizations not yet performed

Paper 2017-01-0645 13

3000rpm x 11bar (FL)

SYSTEM SIMULATION ANALYSIS

RESULTS

slide-14
SLIDE 14

SAE INTERNATIONAL

Corrected ISFC

  • 3000rpm x 11bar  10g/kWh benefit for the reverse configuration
  • 2000rpm x 7bar  small benefit for the reverse configuration (>5 g/kWh)
  • 1500rpm x 4bar  negligible benefit

Paper 2017-01-0645 14

1500rpm x 4bar 2000rpm x 7bar 3000rpm x 11bar (FL)

SYSTEM SIMULATION ANALYSIS

RESULTS

slide-15
SLIDE 15

SAE INTERNATIONAL

Analysis of the fresh gases masses

  • Charging ratio = mass of trapped fresh gases / reference mass based on the intake conditions
  • Expansion / compression ratio = Vcylinder @ exhaust opening / Vcylinder @ intake closure
  • Larger expansion for the reverse configuration
  • Penalty on the charging ratio  but penalty ÷2 for the FL point
  • Compensation of expansion benefit and charging penalty

15

1500rpm x 4bar 2000rpm x 7bar 3000rpm x 11bar (FL)

  • 3%

SYSTEM SIMULATION ANALYSIS

RESULTS

  • 7%
  • 7%

+30%

slide-16
SLIDE 16

SAE INTERNATIONAL

Clear benefit of the reverse uniflow for the full load point  -10 g/kWh but the advantages are negligible at low loads/speeds

  • Reverse configuration allows a larger expansion but there is a penalty of the trapped mass
  • For the full load point, the penalty is small compared to the expansion benefit
  • For the other mid-load points, both effects compensate

Conclusions drawn by assuming the same scavenging between both uniflow configurations

Paper 2017-01-0645

SYSTEM SIMULATION ANALYSIS

CONCLUSIONS

slide-17
SLIDE 17

SAE INTERNATIONAL

1. INTRODUCTION

  • CONTEXT
  • OVERVIEW OF SCAVENGING ARCHITECTURES
  • BENCHMARK OF SCAVENGING CONFIGURATIONS

2. SYSTEM SIMULATION ANALYSIS

  • INTRODUCTION
  • SIMULATION METHODOLOGY
  • RESULTS
  • CONCLUSIONS

3. 3D CFD ANALYSIS

  • INTRODUCTION
  • SIMULATIONS DETAILS
  • QUALITATIVE RESULTS
  • QUANTITATIVE RESULTS

4. MAIN CONCLUSIONS & PERSPECTIVES

Paper 2017-01-0645 17

slide-18
SLIDE 18

SAE INTERNATIONAL

Purpose

  • Study of the efficiency of the scavenging for the standard

and reverse configurations

  • CONVERGE code
  • Comparison of the

– Scavenging curves – Charging, trapping ratios – Swirl

  • Single operating point 3750rpm x 11bar
  • Single intake/exhaust diagrams issued from the previous study

Engine configuration

  • Same as previously

3D CFD ANALYSIS

INTRODUCTION

slide-19
SLIDE 19

SAE INTERNATIONAL

Three investigated cases

  • Benchmark of the uniflow configurations

– Case 1 : standard uniflow – Case 2 : reverse uniflow with intake ducts typed for enabling filling

  • Benchmark of intake ducts in rev. uniflow

– Case 2 : reverse uniflow with intake ducts typed for enabling filling – Case 3 : reverse uniflow with intake ducts typed for enabling swirl Case 1 standard Case 2 reverse Case 3 reverse

3D CFD ANALYSIS

INVESTIGATED CASES

slide-20
SLIDE 20

SAE INTERNATIONAL

Methodology

  • From the end of the expansion to the beginning of the compression
  • Best intake and exhaust diagrams issued from the previous study

Automatic grid generation

  • Base size = 4mm
  • Refinement up to 0.5mm
  • 750,000 cells

Numerical setup

  • k-e RNG
  • No-slip hydraulically smooth walls

with a standard law-of-the-wall

  • CFLconvective < 1
  • CFLacoustic < 50

1 day on 64 Intel Xeon E5 @ 2.60GHz

3D CFD ANALYSIS

SIMULATIONS DETAILS Standard Uniflow Reverse Uniflow

Intake duration 125 CAD 100 CAD Intake opening 117 CAD ATDC 150 CAD ATDC Exhaust duration 95 CAD 120 CAD Exhaust opening 105 CAD ATDC 120 CAD ATDC

slide-21
SLIDE 21

SAE INTERNATIONAL

Qualitative results

  • In-cylinder tracer fields
  • Center slice

Paper 2017-01-0645

Case 1 standard uniflow

3D CFD ANALYSIS

QUALITATIVE RESULTS

slide-22
SLIDE 22

SAE INTERNATIONAL

Qualitative results

  • In-cylinder tracer fields
  • Center slice

Paper 2017-01-0645

Case 1 standard uniflow Case 2 reverse uniflow

3D CFD ANALYSIS

QUALITATIVE RESULTS

slide-23
SLIDE 23

SAE INTERNATIONAL

Qualitative results

  • In-cylinder tracer fields
  • Center slice

Paper 2017-01-0645

Case 1 standard uniflow Case 2 reverse uniflow Case 3 reverse uniflow

3D CFD ANALYSIS

QUALITATIVE RESULTS

slide-24
SLIDE 24

SAE INTERNATIONAL

Quantitative results

  • Best scavenging for the standard uniflow (case 1)
  • For the reverse uniflow, swirl penalizes the efficiency of the scavenging
  • Scavenging characteristics

– Charging ratio = mass of trapped fresh gases / reference mass based on the intake conditions – Scavenging ratio = mass of trapped fresh gases / total in-cylinder mass of gases

Case 1 Standard Case 2 Reverse Case 3 Reverse

Trapping ratio 91% 82% 68% Scavenging ratio 88% 83% 77% Swirl number 1.0 0.2 2.4

Paper 2017-01-0645

3D CFD ANALYSIS

QUANTITATIVE RESULTS

slide-25
SLIDE 25

SAE INTERNATIONAL

1. INTRODUCTION

  • CONTEXT
  • OVERVIEW OF SCAVENGING ARCHITECTURES
  • BENCHMARK OF SCAVENGING CONFIGURATIONS

2. SYSTEM SIMULATION ANALYSIS

  • INTRODUCTION
  • SIMULATION METHODOLOGY
  • RESULTS
  • CONCLUSIONS

3. 3D CFD ANALYSIS

  • INTRODUCTION
  • SIMULATIONS DETAILS
  • QUALITATIVE RESULTS
  • QUANTITATIVE RESULTS

4. MAIN CONCLUSIONS & PERSPECTIVES

Paper 2017-01-0645 25

slide-26
SLIDE 26

SAE INTERNATIONAL

Conclusions

  • Development of an efficient 2-stroke Diesel engine for medium passenger cars
  • First step of the project = choice between standard or reverse uniflow
  • Corrected ISFC assessment

– 10 g/kWh benefit for the reverse conf. for the full load point – Benefit vanishes for mid-load points

  • Feasibility of the scavenging

– More efficient scavenging for the standard configuration – Previous ISFC benefit potentially lost in the scavenging

 The standard uniflow is preferred

Paper 2017-01-0645

MAIN CONCLUSIONS & PERSPECTIVES

slide-27
SLIDE 27

SAE INTERNATIONAL

Future steps

  • Choice of the best suited stroke-to-bore ratio
  • Optimization of the transfer ports geometry
  • Definition of the combustion system
  • Experimental test campaigns on SCE
  • Extrapolation of the fuel consumption/emissions in normalized driving cycles

Paper 2017-01-0645

MAIN CONCLUSIONS & PERSPECTIVES

slide-28
SLIDE 28

SAE INTERNATIONAL Paper # (if applicable) 28

www.ifpenergiesnouvelles.com @IFPENinnovation Find us on:

Contact: jeremy.galpin@ifpen.fr

QUESTIONS ?

slide-29
SLIDE 29

SAE INTERNATIONAL

IGR axial distribution at intake closure

  • Case 1 = homogeneous distribution
  • Case 2

– Pockets of IGR in the piston or close to the head – Increasing DP or delaying slightly exhaust closure  Possibility to pursue the scavenging with a minimal cost on the trapping ratio

  • Case 3 = homogeneous distribution

Paper 2017-01-0645

3D CFD ANALYSIS

QUANTITATIVE RESULTS