USE OF 1D SIMULATION IN THE COOLING SYSTEMS DESIGN PROCESS

Transcription

1 Dr. Bernhard Zuck; USE OF 1D SIMULATION IN THE COOLING SYSTEMS DESIGN PROCESS FROM SYSTEM CONCEPT TO FINAL VALIDATION

2 CONTENT 1. Demands and challenges facing Simulation 2. Considered System 3. Accuracy and reliability 4. Solution / Process From Concept to validation, BMW Group, Seite 2

3 DEMANDS AND CHALLENGES FACING SIMULATION

4 DEMANDS FACING SIMULATION Simulation Testing Initial proposals evaluation Understanding the system behaviour Comparison Dimensioning Influence e Simulation andvancement Determine component targets Interpret test results Validation 20% 10% 0% Time to SOP [months] From Concept to validation, BMW Group, Seite 4

5 DEMANDS FACING DEVELOPMENT torque Hill climbing Race track Cooling is normaly not influencing the buying decision Legal tests for fuel consumption do not require high engine loads Customers use the cars in very different ways under different circumstances Heating engine speed Most extreme situations arise on racetracks The design of the cooling system needs to be adopted to higher loads The cooling system should be dimensioned to reach requirements exactly From Concept to validation, BMW Group, Seite 5

6 CHALLENGES FOR THE COOLING SYSTEM The last 10 to 15 years thermal management systems have become more and more important with respect to fuel consumption, emissions and passanger comfort The boundary conditions package, costs, weight, vehicle design, make the task continuously more demanding Downsizing leads to more and more charged engines Increasing engine power, higher demand concerning charge air temperatur, minimise air drag, faster rate of change of heat input New demands from hybrid and electric powertrains The simple task of designing an adapted cooling systems becomes a challenge again From Concept to validation, BMW Group, Seite 6

7 CHALLENGES FOR SIMULATION Status: Numerous publications in the last years have allways shown good correlation" between simulation and meassured results especially concerning fuel consumption Challenges: Shorter time to market Expanded range of car types Increasing number of derivatives More complex systems Interacting systems need reliable results earlier for decisions Shift from hardware-testing to virtual methods Earlier Faster More reliable From Concept to validation, BMW Group, Seite 7

8 DEVELOPMENT FOCUS Predevelop ment Early Concept Phase Later Concept Phase Series Develop ment SOP Input: Challenge: Intention: Input: Challenge: Intention: Input: Challenge: Intention: Input: Challenge: Intention: Input: Challenge: Intention: new possibilities, new requirements / requests new concepts, but many considered inputdata defining solutions known requirements (Package, power needed, ) concepts + dimensioning, data still unstable solutions for critical and most important variants first measured component-data many derivatives and variations Evaluation and comparissons, performance and costs meassured data from vehicle prototypes accuracy and derivatives optimisation of derivatives meassured data from series vehicles accuracy enhance the simulation velocity accuracy

9 THE CONSIDERED SYSTEM

10 MODEL COMPLEXITY VERSUS SIMULATION REQUIREMENTS 100% 80% 60% 40% HEV ICM 20% 0% From Concept to validation, BMW Group, Seite 10

11 DEFINING THE SYSTEM tim mescale fast Not considered Oscill ation Fuel injection numbers Combustion maps Detailled modelling heat map Speed T.Coolant T.Engine slow low Asphalt Weather effect T.Air Weight high -Best results are achieved with a target-oriented model -Effect and timescale are the major factors, what to integrate From Concept to validation, BMW Group, Seite 11

12 CONSIDERED SYSTEM cycle vehicle, driver, drivetrain engine aerodynamics cooling system ECU environment interior: A/C From Concept to validation, BMW Group, Seite 12

13 COOLING SYSTEM Air intake Charger CAC Engine Turbine Exaust pipe Condenser Auxil. units HT / LT Heat exchanger Oil cooler Oil cooler Transmission Fan Drivetrain Engine compartement Wheels Air / Gas Cooling Air Heat flow Mech. / el. Power From Concept to validation, BMW Group, Seite 13

14 MODEL DETAILS CAD GEM 3D-CFD Circuit model Map Test From Concept to validation, BMW Group, Seite 14

15 MAIN INTERFACES OF THE COOLING SYSTEM Engine: heat load, temperature targets, pressure loss, coolant, oil, charge air Gearbox: gear ratio, efficiency, targets Application of engine and transmission Drivetrain: efficiency, engine speed and torque Vehicle: weight, aerodynamic drag, cooling air Climatisation: heat load / sink Package: size of heat exchangers, piping Design: aerodynamics, cooling air Electric system: power for fan and pumps, Electronic system : heat load, temperature targets ECU: control of fan, pumps, valves, protective functions From Concept to validation, BMW Group, Seite 15

16 ACCURACY AND RELIABILITY

17 ACCURACY AND RELIABILITY Numerics Included physical and technical fundamentals Mode of modelling Inputdata for components: meassured by oneself, other departments or suppliers Boundary conditions From Concept to validation, BMW Group, Seite 17

18 REACHABLE ACCURACY Max. erro or [%] vehicle uncertanties New engine technology Known engine Target Time to SOP [months] From Concept to validation, BMW Group, Seite 18

19 VALIDATION From Concept to validation, BMW Group, Seite 19

20 PROCESS AND RESULTS

21 PROCESS Vehicle Main Data Pool Main Sheet GT Data base CAD Engine Transmission Engine Transmission GEM In house partners Application Electronics Alternators A/C Macros Application Electronics Alternators A/C Projec ct editor GT Simulation Suppliers Heat exchanger Fan Thermostat Pump Heat exchanger Fan Thermostat Pump Post processing Fluid propertys Fluid propertys Driver Result Data base Piping Airpath From Concept to validation, BMW Group, Seite 21

22 PROJECT EDITOR Vehicle Engine max. Power CAC System Land- Variante Hanger drive transmissiono drive chain wheels weight drag size Coolant pump piping air A/C fan thermostat radiators oil cooler CAC cycle 1 A 160 direkt 2WD a /55 R mech 1 A A A A A A A Cooling 2 B 300 indirekt HL Ja 4WD b /55 R mech 2 B B B B B B D Cooling 3 A 160 direkt 4WD a /55 R el. 3 A A A A A A A Cooling 4 C 225 direkt 2WD b /55 R el. 4 C C C C C C A Cooling 8 C 225 direkt 2WD b /55 R el. 8 C C C C C C A Cooling 9 A 160 direkt 2WD a /55 R el. 9 A A A A A A A Cooling 13 D 400 indirekt HL Ja 4WD b /50 R mech 13 D D D D D D D Cooling 14 A 160 direkt 2WD b /50 R el. 14 A A A A A A A Cooling 15 B 300 indirekt 2WD a /50 R mech 15B B B B B B D Cooling 16 A 160 direkt 2WD b /50 R el. 16 A A A A A A A Cooling 17 C 225 direkt 2WD a /50 R el. 17 C C C C C C A Cooling 18 A 160 direkt 2WD b /50 R el. 18 A A A A A A A NEFZ 19 D 400 indirekt 2WD b /50 R mech 19 D D D D D D D NEFZ 20 B 300 indirekt 2WD b /50 R mech 20 B B B B B B D NEFZ -All necessary parameters for a number of derivatives are defind in one list -Each line is translated into a GT-model From Concept to validation, BMW Group, Seite 22

23 VELOCITY Standards for modelling Optimised modells Standard process Automatisation Project editor Parallel computing Close teamwork 0 turnaround time Derivatives Systems From Concept to validation, BMW Group, Seite 23

24 ACCURACY Max deviation [% %] Coolant Engine Oil Transmission Oil coolan nt Engine oil Transmission oil Charge air Standards for modelling Standard process Automatisation Close teamwork Steady validation on each level Understanding tests and simulation From Concept to validation, BMW Group, Seite 24

25 DYNAMIC SIMULATION Racetrack Hill Climbing Tempe erature Oil coolant Time [s] Time [s] Dynamic cases are the basis for the final validation Differences to real road tests at the peak temperature are below 5K / 2K From Concept to validation, BMW Group, Seite 25

26 CONCLUSION Simulation of the cooling system is a very complex task At BMW we have installed processes providing fast accurate results reaching from the concept phase to the final validation To fullfill all future requirements these processes have to be flexible Further development is part of our process From Concept to validation, BMW Group, Seite 26