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© Ricardo plc 2005 Gasoline & Diesel Engineering Fluid Simulation Tools Ricardo Japan TSA Visits November 2005 RD.05/406501.1.

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Presentation on theme: "© Ricardo plc 2005 Gasoline & Diesel Engineering Fluid Simulation Tools Ricardo Japan TSA Visits November 2005 RD.05/406501.1."— Presentation transcript:

1 © Ricardo plc 2005 Gasoline & Diesel Engineering Fluid Simulation Tools Ricardo Japan TSA Visits November 2005 RD.05/

2 © Ricardo plc 2005 RD05/ Agenda  Background Background  Combustion System Simulation Combustion System Simulation  Intake, Exhaust and Aftertreatment System Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling Engine Thermal Modelling  Crankcase Breathing Crankcase Breathing  Vehicle Simulation Vehicle Simulation

3 © Ricardo plc 2005 RD05/ Agenda  Background  Combustion System Simulation  Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling  Crankcase Breathing  Vehicle Simulation

4 © Ricardo plc 2005 RD05/ Background  Simulation technology has ability to reduce product development cycle significantly  Principal requirements are: –Robust analysis methodology capable of capturing major physical parameters through direct modelling or correlated database information –Rapid analysis toolset to provide engineering direction for component / system / powertrain development –Validated modelling approach allowing predictive application to engineering projects Presentation will outline fluid simulation application processes to allow technologies application on powertrain development projects leading to reduced product development cycles

5 © Ricardo plc 2005 RD05/ Agenda  Background  Combustion System Simulation  Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling  Crankcase Breathing  Vehicle Simulation

6 © Ricardo plc 2005 RD05/ Combustion System Simulation  Combustion system tools and techniques research forms primary stages in application of simulation to combustion system development  Tools and techniques allow predictive application of some modelling technology to development Ongoing detailed tools and techniques programme measuring gasoline and diesel fuel spray behaviour under realistic engine operating conditions Experimental techniques to measure fundamental physical processes for basic validation of CFD codes Development of modelling processes following fundamental validation for application to engineering programmes Continual process of methodology evolution and development with validation against test programmes where applicable

7 © Ricardo plc 2005 RD05/ Fuel Spray Measurement and Validation  Gasoline spray and mixture measurement –Quiescent fuel spray characterisation –MIE scattering measurements in motored engine homogeneous operation stratified operation –Quantitative LIF measurement  Diesel spray and mixture measurement –Quiescent spray bomb characterisation –Ricardo Diesel spray rig Provides cylinder conditions close to engine cylinder conditions  Validation techniques applied to VECTIS and Star CD Mie Camera Optical Engine Laser Sheet Viewing Annulus LIF Camera

8 © Ricardo plc 2005 RD05/ Gasoline Engine Application Process  Gasoline combustion system design support  3D CFD simulation applications include –PFI and GDI combustion system development –Cold start mixture preparation simulation –Combustion and emissions prediction for conventional or HCCI operation –Knock prediction development Combustion System

9 © Ricardo plc 2005 RD05/ Gasoline Engine Application Process  Principal issues for simulation focus –Geometry definition Model exactly what will or has been tested –Spray modelling Injector characterisation and spray match –Wall film prediction –Boundary conditions Flow conditions (high speed pressure data from 1D / test) Thermal boundary conditions

10 © Ricardo plc 2005 RD05/ Case Study – Gasoline HCCI  Ricardo Gasoline Engine HCCI combustion Research Combustion system design Modelling tools VECTIS WAVE Four-stroke engines 1-D3-D Optical engines Conventional engines Two-stroke engines Conventional engines Optical engines Combustion System

11 © Ricardo plc 2005 RD05/ Case Study – Gasoline HCCI  Uncertainties encountered in the modeling study of HCCI engine combustion –Charge inhomogeneity Thermal inhomogeneity Composition inhomogeneity –Trapped conditions High percentage of trapped residuals, difficult to measure experimentally  Simulation strategy –Full 3-D CFD simulation to cover all processes included in the engine cycle –Multi-cycle simulation approach to eliminate the uncertainties regarding trapped conditions –Compact ignition and combustion models for computational efficiency Combustion System

12 © Ricardo plc 2005 RD05/ Case Study - 2-stroke Gasoline HCCI  Engine Configuration –Upright intake ports –4 poppet valves –Pent roof combustion chamber –Flat piston –Swept volume 325cc –Compression ratio 9.0 –Loop scavenging  Valve and injection timing Combustion System TDC BDC IVO IVC EVC EVO SOI CA

13 © Ricardo plc 2005 RD05/ Case Study - 2-stroke - Simulation Cases IMEP [bar] Engine Speed [rev/min] A B C D HCCI Operation Combustion System

14 © Ricardo plc 2005 RD05/ Case Study – 2-stroke – Simulation Approach  Start position after the end of combustion but before exhaust valve opening –Initial cylinder pressure from experimental measurement –other initial conditions estimated  Pressure boundary conditions applied at the intake port entrance and exhaust port exit –Boundary pressures taken from the recorded dynamic pressures from engine test  Multi-cycle combustion simulation performed until a cyclically-converged solution obtained –Ignition control variable and combustion species re-initialized once every cycle  Ignition model scaling coefficient Cig tuned in the first case, then kept unchanged for the remaining simulations –No tuning of combustion model performed Combustion System

15 © Ricardo plc 2005 RD05/ Case Study – 2-stroke – Simulation Results: In-cylinder Processes Combustion System

16 © Ricardo plc 2005 RD05/ Case Study – 2-stroke – Simulation Results: Charge Inhomogeneity  Under 2-stroke operation the in-cylinder charge inhomogeneity can be significant  A quantitative description of inhomogeneity can be provided by using the distribution density function –DDF - a probability density function of the representative variables Combustion System

17 © Ricardo plc 2005 RD05/ Case Study – 2-stroke – Simulation Results: NOx Emission  NOx prediction based on the extended Zeldovich mechanism, considering thermal NO only  NOx volume fraction monitored at the far end of exhaust port and averaged over a cycle  Correct trend and order of magnitude  A general over-prediction of 30%  Under-prediction in Case A may be attributed to neglecting prompt NOx Combustion System

18 © Ricardo plc 2005 RD05/ Diesel Engine Application Process  HSDI combustion system development simulation support –1D performance simulation Advanced air handling and EGR system development Advanced aftertreatment modelling –3D CFD simulation Fuel – air mixing and combustion for bowl design and swirl development Combustion prediction for emissions modelling –Intake port development Steady state air motion development Combustion System

19 © Ricardo plc 2005 RD05/ Diesel Engine Application Process  Pragmatic approach for rapid application to diesel combustion system simulation –3D CFD analysis for base system definition Rapid assessment of critical hardware –Swirl level, chamber design Specification of initial system for engine demonstration –FIE requirements –Air motion requirements Full load/part load compromise –Compression ratio selection –Combustion chamber geometry definition Combustion modelling for emissions prediction –Engine testing for detailed development using DoE based calibration Tuning of protrusion and nozzle flow Engine calibration –EGR rate, injection timing, injection specification Combustion System

20 © Ricardo plc 2005 RD05/ Diesel Engine Application Process  Combustion system issues for accurate simulation –Geometry definition Compression ratio volume match Trapped mass –Imposition of boundary conditions for closed cycle simulation –Multiple full cycle simulations to converge trapped conditions –Coupled 1D/3D in-cylinder for complete engine system modelling –Spray modelling Fundamental spray match has developed accurate process for modelling –Combustion modelling Application of RTZF model in VECTIS

21 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance  Geometry assembly –Closed volume at IVC  Mesh generation  Analysis –Fuel/air mixing only –Analysis starts at IVC Post-processing Results analysis and engineering review is always critical Combustion System Methodology – Overall Approach

22 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance  Multi-dimensional modelling of in-cylinder flow and spray –Gas phase Equations solved in 3-D, Cartesian co-ordinates for conservation of mass, momentum, energy and k-  turbulence model –Liquid phase Discrete droplet model Lagrangian tracking of droplet parcels and heat and mass transfer through mesh for PDE solution Sub-models –Huh-Gosman atomisation model –Secondary droplet break-up Reitz-Diwakar Liu-Mather-Reitz Patterson-Reitz –Droplet-turbulence interactions –Droplet-droplet interactions Validated against diesel spray rig Combustion System Methodology - Fuel Spray Modelling

23 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance  Velocity and fuel vapour field plots require experience and time to interpret –Move towards quantitative representations of data though development of objective measures to quantify changes –Criteria developed and measurable parameters correlated against engine data  Assessment methodology for fuel/air mixing –2 level zone analysis Combustion chamber split into distinct zones Equivalence ratio and fuel vapour distribution within each zone is assessed Combustion System Methodology – Results Analysis

24 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance  Combustion system demonstrator program requiring “right first time” development approach  Program targets –Rated power > 60 kW/l –Peak torque > 200 Nm/l –EURO 4 emissions level  Results shown for initial nozzle specification study comparing 6 hole against 7 hole for the same flow specification Combustion System

25 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance 6 hole nozzle shows improved mixing within favourable zone Increased combustible mixture present Combustion System Methodology – Results Overview

26 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance 7 hole nozzle shows worse mixture retention - Increased combustible and rich mixture close to bore wall Combustion System Methodology – Results Overview

27 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance 7 hole nozzle shows less bowl interaction with reduced mixture in Zone D Combustion System Methodology – Results Overview

28 © Ricardo plc 2005 RD05/ Case Study – Diesel Fuel/Air Mixing for High Performance 6 hole nozzle shows improved smoke/AFR trade off performance Combustion System Comparison of Combustion System Performance from Test Data

29 © Ricardo plc 2005 RD05/ Case Study – Diesel Combustion Modelling  Overview –Auto-ignition by delay probability integral –Simplified coherent flamesheet model with two-zone gas representation –Emissions chemistry post-processing  Two-zone model –Burnt and unburnt  Each zone has its own enthalpy, fuel mass fraction and air mass fraction  Transport equations solved for –6 mass fractions, 1 auto-ignition PDF, 4 segregation mass fractions, 2 emissions, 3 enthalpies  3 temperatures calculated for each cell –Overall, burned and unburned  Fast reactions based on chemical equilibrium calculations –11 species Ricardo Two Zone Flamesheet Model Explanation

30 © Ricardo plc 2005 RD05/ Case Study – Diesel CFD Combustion Simulation  Two-stage simulation –Compression stroke simulation from IVC to SOI Swirl imposed as solid body rotation at IVC (based on steady flow rig data) Trapped mass calculated based on measured fuelling and air/fuel ratio (including EGR) Solving for momentum, continuity, turbulence and energy –Spray and combustion simulation from SOI to EVO Spray: Lagrangian discrete droplet method with Patterson-Reitz droplet breakup model Combustion: RTZF combustion model NOx: extended Zeldovich NOx model Analysis Process

31 © Ricardo plc 2005 RD05/ Case Study – Diesel CFD Combustion Simulation  HSDI engine running at full load –4000 rev/min full load –Injection timing swing  Combustion modelling prediction –Development of fuel/air mixing analysis process –Animation showing temperature distribution within chamber at rated speed full load Operating Conditions

32 © Ricardo plc 2005 RD05/ Case Study – Diesel CFD Combustion Simulation  Cylinder pressure trends well produced Combustion Modelling Results

33 © Ricardo plc 2005 RD05/ Case Study – Diesel CFD Combustion Simulation  NOx emissions trend well reproduced Combustion Modelling Results

34 © Ricardo plc 2005 RD05/ Case Study – Diesel CFD Combustion Simulation  Combustion modelling experience shows cylinder pressure generally well reproduced –Over-predicted at earlier timings –Under-predicted at later timings –SOC generally captured well  NOx emissions trend well reproduced –NOx decreases with injection retard –Follows cylinder pressure trend NOx over-predicted at early timings NOx under-predicted at later timings  CFD analysis provides valuable information and understanding the HSDI combustion processes to support analytical system development  Routine application to diesel system development including: –Air motion generation and requirements –Combustion chamber geometric configuration –FIE system configuration Combustion Modelling Summary

35 © Ricardo plc 2005 RD05/ Agenda  Background  Combustion System Simulation  Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling  Crankcase Breathing  Vehicle Simulation

36 © Ricardo plc 2005 RD05/ Intake System Simulation Applications  Intake system –1D performance simulation Intake system design Boosting system design and development –3D CFD Flow performance prediction AFR distribution prediction EGR distribution prediction –Flow testing Manifold flow assessment Intake, Exhaust and Aftertreatment

37 © Ricardo plc 2005 RD05/ Exhaust System Simulation Applications  Exhaust system –1D performance simulation Exhaust system design Boosting systems Warm-up modelling –3D CFD Flow distribution assessment Transient performance predictions Coupled fluid/thermal modelling Catalyst flow predictions Intake, Exhaust and Aftertreatment

38 © Ricardo plc 2005 RD05/ Intake and Exhaust System Simulation Methodology  Coupled 1D/3D simulation used extensively as a routine application on exhaust and intake system modelling –Improved modelling for 1-D simulation –Improved boundary conditions for 3-D simulation –Provide a tool to address a wide range of technical problems Intake system – Air / EGR distribution Exhaust system – Flow performance / catalyst flow distribution EGR system – Flow performance / dynamic behaviour –Assess impact of development on engine performance  Integration is characterised by coupling at a time-step level the 1-D gas dynamic code (WAVE) and a 3-D CFD code (VECTIS/STAR-CD) Intake, Exhaust and Aftertreatment

39 © Ricardo plc 2005 RD05/  Base manifold design support project using CFD and FE analysis to drive manifold design  Vehicle application required use of close coupled catalyst but package constraints were stringent  Focus of fluid simulation –Assess performance benefit of compared to 4-1 manifold –Assess catalyst flow distribution and recommend design development –Assess sensor location Design 1 Design 2b Case Study – Exhaust System Simulation Intake, Exhaust and Aftertreatment Background

40 © Ricardo plc 2005 RD05/ Case Study – Exhaust System Simulation  Engine package models integrated rapidly into CFD tool and mesh generated automatically  Catalyst model used test data to match test rig pressure drop  Coupled 1D/3D analysis undertaken at part load 50 km/hr cruise condition –1600 rev/min 15 Nm torque  Coupled 1D/3D uses shadow 1-D network for “n” cycles followed by embedded 3-D model with full two-way exchange of boundary conditions at time step level Intake, Exhaust and Aftertreatment Analysis Process 1-D flow region

41 © Ricardo plc 2005 RD05/ Case Study – Exhaust System Simulation  Flow distribution assessed in three ways –Maldistribution - SAE –Uniformity index (g) - SAE –Cumulative velocity PDF Intake, Exhaust and Aftertreatment Assessment Criteria

42 © Ricardo plc 2005 RD05/ Design 1 Design 2b Case Study – Exhaust System Simulation  PDF indicates reasonably well distributed flow  Uniformity index = 0.93  Velocity PDF indicates better velocity distribution compared to Designs 1 and 2  Uniformity index = 0.99 Intake, Exhaust and Aftertreatment Part Load Simulation Results

43 © Ricardo plc 2005 RD05/ Design 1 Design 2b Case Study – Exhaust System Simulation  Assessment of sensor location based on individual cylinder contribution to flow at specified sensor location  Design 1 shows a good balance of individual cylinders present at baseline sensor position  Design 2 shows a poor balance of individual cylinders present at “design” O2 sensor position –Dominated by CYLINDER 2 Intake, Exhaust and Aftertreatment Sensor Location Assessment

44 © Ricardo plc 2005 RD05/ Case Study – Exhaust System Simulation  Design 2 Part Load –Alternative sensor locations assessed rapidly through extraction of revised simulation results for various locations Sensor 1 Sensor 2 Intake, Exhaust and Aftertreatment Alternative Lambda/O2 Sensors

45 © Ricardo plc 2005 RD05/ Aftertreatment Simulation - Emissions Control Technology (ECT) Model Range  Diesel –Diesel Oxy-Catalyst (DOC) –Diesel Particulate Filter (DPF) (including CRDPF and CDPF) –Lean NOx Traps (LNT) –Urea Selective Catalyst Reduction (SCR)  Gasoline –Three Way Catalyst (TWC) –Lean NOx Traps (LNT) DPF flow CRDPF Intake, Exhaust and Aftertreatment Background

46 © Ricardo plc 2005 RD05/ Aftertreatment Simulation – Methodology Exhaust system building from component blocks DPF SCR DOC DPF SCR Common vectorised approach passes species from unit to unit Intake, Exhaust and Aftertreatment ECT System Design

47 © Ricardo plc 2005 RD05/ Methodology – ECT General Model Structure Thermal sub-model Pressure sub-model Catalysis sub-model maf P T O 2 NO NO 2 Pm HC CO SOx CO 2 etc. maf P T O 2 NO NO 2 Pm HC CO SOx CO 2 etc. Engine MAPS Speed Load Geometry Material properties maf T emissions Intake, Exhaust and Aftertreatment ECT General Model Structure

48 © Ricardo plc 2005 RD05/ Case Study – Aftertreatment Assessment of Exhaust System Layout  Project to assess a number of different exhaust configurations in different vehicle packages (Front facing, rear facing, CC CDPF)  Analysis set-up as shown (test data based)  Investigations included assessment of –System specification including insulated pipes –Different catalyst specifications Background

49 © Ricardo plc 2005 RD05/ Case Study – Aftertreatment Assessment of Exhaust System Layout  Example comparison of cumulative emissions post DOC for under floor against close coupled 1.20 g/km 0.40 g/km 0.24 g/km 0.09 g/km Example Cycle Emissions Data

50 © Ricardo plc 2005 RD05/ Case Study – Aftertreatment Assessment of Exhaust System Layout Conversion Matrix for Assessed System Configurations

51 © Ricardo plc 2005 RD05/ Aftertreatment Simulation – Methodology  Co-simulation: V-SIM ECT models can be linked to VECTIS or Star CD to increase the resolution of the airflow and concentration distribution over the catalyst front face I.e. SCR system simulation  Link 1-D chemistry and thermal models from the VSIM environment to a CFD airflow prediction model  Investigate parameters including –Light off of close-coupled catalyst –Ammonia slip  Analysis of airflow maldistribution impact on emissions performance and potential cost/benefit ratio investigations from package/aftertreatment configuration changes Coupling V-SIM ECT & CFD Methodology

52 © Ricardo plc 2005 RD05/ Aftertreatment Simulation – Methodology  CFD simulation at selected engine keypoints –Output transient flow distribution on the catalyst face –Average flow over entire engine cycle Coupling V-SIM ECT & CFD Methodology SUM / Nsteps CYCLE AVERAGE RESULTS

53 © Ricardo plc 2005 RD05/ Aftertreatment Simulation – Methodology  CFD simulation output –Discretise front face according to zones of similar mass airflow  Use outputs from front face discretisation (average airflow in each zone, heat transfer area between zone i and zone j) to connect a set of 1D ECT models together, ultimately providing a 3D model Coupling V-SIM ECT & CFD Methodology

54 © Ricardo plc 2005 RD05/ Agenda  Background  Combustion System Simulation  Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling  Crankcase Breathing  Vehicle Simulation

55 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Toolset for application to thermal development of base engine components  Engineering development applied through use of advanced analysis tools providing understanding of principal issues  Fluid simulation analysis capabilities include: –Steady flow coolant circuit simulation coupled to external circuit modelling –Coupled fluid/thermal simulation for steady state and transient engine thermal modelling COMPLETE ENGINE ASSEMBLY MODELLING Engine Thermal Modelling Background

56 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Principal tools applied –Conjugate heat transfer analysis Localised coolant warm-up effect modelled with nucleate boiling and buoyancy modelling in low / no flow regimes –Steady state and transient thermal predictions with transient thermal boundary condition application for warm-up/drive cycle simulation –Prediction of: Peak temperature distribution during early engine definition, capturing cylinder to cylinder variation in metal temperatures Thermal shock modelling Engine warm up modelling during cold start Heat soak thermal prediction Assessment of thermal sensor location for capture of engine response Detailed engine thermal mapping for application of controlled cooling flow regimes NUCLEATE BOILING VALIDATION Engine Thermal Modelling Background

57 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Application of CFD analysis to optimise the coolant flow system for: –Cylinder to cylinder flow distribution –Flow within recommended velocity guidelines –Strategic cooling and heat transfer in critical areas –Minimisation of areas of stagnant flow and excessive flow velocity –Minimum pressure drop –Fast warm-up  Engineering solutions to issues delivered rapidly to address project issues Engine Thermal Modelling Coolant Flow Simulation

58 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Poor cooling of upstream inlet/exhaust valve bridge  Features added to guide alternative source of flow  Head coolant volume reduced by sculptured water jacket (0.7l) Engine Thermal Modelling Coolant Flow Simulation

59 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Complete engine assembly for half of a V-6 engine  Fluid flow CFD domain consists of head, gasket and cylinder block –Conventional longitudinal flow regime  Sub-cooled nucleate boiling model developed for these applications allowed  Assessment of boiling level and cause within engine structure Engine Thermal Modelling Nucleate Boiling Study

60 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Comparison of predicted metal temperature field with boiling model NO NUCLEATE BOILING MODELLED NUCLEATE BOILING MODELLED Engine Thermal Modelling Nucleate Boiling Study

61 © Ricardo plc 2005 RD05/ Base Engine Thermal Development  Nucleate boiling modelling capability allows: –Assessment of risk of boiling onset within engine configuration prevention of excessive localised boiling leading to erosion issues –Specification of system components to inhibit boiling within engine –Optimisation of cooling system to minimise boiling risk providing optimised margin allowing for increased local heat transfer should boiling occur Engine Thermal Modelling Nucleate Boiling Study

62 © Ricardo plc 2005 RD05/ Engine Transient Thermal Modelling  Build complete engine thermal model from CAD data –Typically at least 15 major components  Steady state or transient thermal boundary conditions calculated –Information input included transient engine flow rates transient fuelling transient gas temperature data from 1D or test data –Instantaneous heat flux calculated Based on input data Distribution data applied and mapped to engine structure  Simulations capabilities include: –Steady state temperature prediction Fixed heat flux, fixed coolant flow, single time –Fixed engine condition warm-up Fixed heat flux, fixed coolant flow, single time –Fully transient warm-up or load step engine condition change Transient heat flux, transient coolant flow, time marching COMPLETE ENGINE ASSEMBLY MODELLING Engine Thermal Modelling Analysis Process

63 © Ricardo plc 2005 RD05/ Case Study – Engine Transient Thermal Modelling CONVENTIONAL WATER PUMP THERMOSAT CLOSED RATED SPEED THERMAL SHOCK FROM 25°C 0 to 65 seconds LOW FLOW WARM-UP THERMOSAT CLOSED RATED SPEED THERMAL SHOCK FROM 25°C 0 to 30 seconds Engine Thermal Shock Modelling

64 © Ricardo plc 2005 RD05/ Case Study – Engine Transient Thermal Modelling CONVENTIONAL WATER PUMP THERMOSAT CLOSED RATED SPEED THERMAL SHOCK FROM 25°C 0 to 30 seconds LOW FLOW WARM-UP THERMOSAT CLOSED RATED SPEED THERMAL SHOCK FROM 25°C 0 to 30 seconds Engine Thermal Shock Modelling Temperature Distribution After 30 Seconds

65 © Ricardo plc 2005 RD05/ Case Study – Engine Transient Thermal Modelling  Transient thermal prediction tools allow system mapping and detailed modelling of powertrain thermal behaviour  Process supports: –Efficient thermal management strategies –Detailed understanding of engine thermal behaviour Summary

66 © Ricardo plc 2005 RD05/ Agenda  Background  Combustion System Simulation  Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling  Crankcase Breathing  Vehicle Simulation

67 © Ricardo plc 2005 RD05/  Engineering closed crankcase breather systems essential for optimisation of engine performance, emissions and durability  Engineering issue path –Minimise engine blow-by Reduce separator system flow requirements Minimise oil carryover –Optimisation of breather system Minimise pumping work for transfer of blow-by gas to intake Optimisation of PCV valve characteristics Maximise crankcase depression –Component optimisation Separator PCV valve  Engine structural implications –Bulkhead design optimisation –Crankshaft profile Crankcase Breathing Simulation Crankcase Breathing Background

68 © Ricardo plc 2005 RD05/ Crankcase Breathing Simulation  Objectives –Prediction of crankcase pumping work –Validation of boundary conditions –Investigation into bay-to-bay breather area effects  Full gas flow path modelled in 1D with WAVE to represent complex 3D geometry –Blow-by flow applied from test data or simulation –Bulk motion predicted in crankcase system Interbay breathing Oil drainback chimneys Chain/gear case flow Cam cover flow PCV valve Blowby Interbay breathing Oil drainback chimneys Chaincase Crankcase Breathing 1D Analysis Methodology

69 © Ricardo plc 2005 RD05/ Crankcase Breathing Simulation  Techniques validated for prediction of system dynamic pressures against engine testbed data  Engine performance impact on oil flow levels and rates can be considered –E.g. piston cooling jets draw additional oil from sump around 2000rpm causing level to drop at this point and as speed increases –Simulation varies the oil level with speed Separator In Simulation Test Crankcase Bay Amplitude (Bar) Crankcase Breathing 1D Analysis Methodology

70 © Ricardo plc 2005 RD05/ Case Study – Crankcase Breathing Simulation  V6 Breather Circuit Study –Model generated using WAVEBUILD-3D to represent volumes –1D model to assess breather system performance based upon areas of concern Reduce velocity variation at separator inlet to improve separator performance Reduce regions of high velocity magnitude throughout system –Block transfers from crankcase to V (  ) and can breathe through head passages only (  ), bypassing V –Use head volumes to damp out pressure fluctuations and provide additional separation Fluctuations at separator in are damped by the increased distance and more restrictive passages than baseline which breathes mainly through centre of banks Crankcase Breathing

71 © Ricardo plc 2005 RD05/ Original, target CPMEP CPMEP with additional breather channel as suggested by WAVE CPMEP with proposed breather removal Crankcase Breathing Simulation  1D Crankcase Simulation –Dynamic system model to match measured high speed crankcase pressures –Provides analysis of system behaviour across engine speed range –Identifies critical speeds for detailed modelling  3D CFD Simulation –Detailed system modelling based on 1D findings –Incorporation of moving geometry Including complete rotating/reciprocating component motion –Simulation of complete crankcase will not model oil mist directly Simulation of mist through high density scalar fraction Liquid modelling for free surface motion possible but adds significant complexity and of low value for dry sump systems –Extraction of detailed pumping work for individual components/system regions Optimisation of breathing/scavenge flow regimes possible Optimisation of geometric configuration to minimise aerodynamic/pumping losses Crankcase Breathing Application to Engine Development

72 © Ricardo plc 2005 RD05/ Crankcase Breathing Simulation  Oil separator development using coupled 1D/3D simulation  Engineering support to cyclone design  Rapid approach using steady state or transient single phase flow analysis or transient 2 phase flow analysis with wall film modelling  Methodology developed to assess separator efficiency based on predicted flow regime Crankcase Breathing 3D Oil Separator Development

73 © Ricardo plc 2005 RD05/ Crankcase Breathing Simulation  Choice of cyclone aided by CFD.  VECTIS shows both the single cyclone and multi cyclone display classical behaviour along their entire length  VECTIS predicts the angular velocity down the complete cyclone length  Knowing the velocity profile allows the cyclone to be matched to the oil particle size distribution Entry 350 rad/s 450 rad/s 650 Rad/s 900 rad/s Crankcase Breathing Case Study – 3D Oil Separator Development – Cyclone Separator Selection

74 © Ricardo plc 2005 RD05/ Crankcase Breathing Simulation Crankcase Breathing Case Study – 3D Oil Separator Development – Transient Flow Analysis

75 © Ricardo plc 2005 RD05/ Agenda  Background  Combustion System Simulation  Intake, Exhaust and Aftertreatment System  Engine Thermal Modelling  Crankcase Breathing  Vehicle Simulation

76 © Ricardo plc 2005 RD05/ Vehicle Simulation  The integrated design of both engine and vehicle hardware are key to meeting performance and emissions targets  Applications include –Matching of engine performance to vehicle weight –Gear ratio selection –Air system control strategy definition and calibration –Boost system selection –Calibration comparison Vehicle Simulation Background

77 © Ricardo plc 2005 RD05/ Vehicle Simulation  Validated steady state WAVE model is converted to transient and coupled to either Vehicle model  ECU developed within Simulink and coupled to vehicle model  The model is run through transient load step / drivecycle manoeuvres Vehicle Simulation Methodology Control systems

78 © Ricardo plc 2005 RD05/ Case Study – Vehicle Simulation Vehicle Simulation Source: Validation  Drive cycle simulation shows engine and vehicle response to gear and pedal position for a fixed manoeuvre validate closely to test data

79 © Ricardo plc 2005 RD05/ Case Study – Vehicle Simulation Vehicle Simulation Source: Validation  Drive cycle simulation shows vehicle fuel consumption through a 1200 second NEDC cycle validates closely to test data

80 © Ricardo plc 2005 RD05/ Case Study – Vehicle Simulation  A number of alternative boost systems were modelled and their acceleration performance compared –Single stage turbocharger –Supercharger + turbocharger –Supercharger only –Electrically driven compressor (EDC) + turbocharger –Electrically Assisted turbocharger –Two stage turbocharger Vehicle Simulation Source: Case Study – Boost System Selection Study

81 © Ricardo plc 2005 RD05/ Case Study – Vehicle Simulation  The baseline system (turbocharger only) was validated to measurements  The controllers for each device were tuned to provide optimum performance  Tip in boost response for two systems –Boost system calibration carried out using simulation models Vehicle Simulation Source: EDC + Turbocharger Turbocharger Only Case Study – Boost System Selection Study

82 © Ricardo plc 2005 RD05/ Case Study – Vehicle Simulation  Each system was run through the same manoeuvre (3 rd gear, 30 km/h, from 0% to 100% Pedal)  For this example the FGT + EDC provided the best response Vehicle Simulation Source: Case Study – Boost System Selection Study

83 © Ricardo plc 2005 RD05/ Thank you for your attention Any Questions? ありがとうございました どうぞご質問を


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