Integrated Engine and Coolant Circuit Modeling with GT-SUITE Oliver Roessler Vincenzo Bevilacqua, Raymond Reinmann 1
Overview Objective Simulation Steps Model build-up & Variants Integration Conclusion 2
Objective Compare GT-Cool with 3D-CFD regarding: Modeling effort Computational time Accuracy Create a methodology for predictive 1D-cooling circuits Build a integrated simulation containing the: Cooling circuit Engine model 3
Simulation Steps Building internal cooling circuit model Same pressure drop function as in 3D-CFD of model Comparison with 3D-CFD results Adding external cooling circuit Using real pipe geometry Using pressure drop maps for heater & cooler Integrated model Integration of coolant & engine model 4
Build-Up & Cooler Cylinderhead Distributor Cylinderblock Bypass Waterpump & Thermostat Heater Function of cooling circuit with thermostat opened 5
Build-Up & Cooler Cylinderhead Distributor Cylinderblock Bypass Waterpump & Thermostat Heater Function of cooling circuit with thermostat closed 6
Build-Up & How detailed should a model be built? Before building a model following points have to be considered: Time consumption (modeling and calibration effort) Complexity of geometry + - Complex Geometry Cylinderhead Cylinderblock Bypass Waterpump & Thermostat Distributor Pipes Gasket + - Time consuming Cylinderhead Cylinderblock Bypass Pipes Waterpump & Thermostat Distributor Gasket All models should be built with same degree of details 7
Build-Up & How to calibrate the model? Discharge coefficients variation, constant for all gasket orifices Volumetric flow Passing: Block In Head Out Gasket orifices Head Distributor Distributor Bypass Distributor Heater Distributor Cooler Pressure drop Block In Head Out Heater Cooler Bypass Target: 1D-results = 3D-CFD-results Discharge coefficient for gasket orifices could be influenced by shape of the geometry 8
Build-Up & Comparison 1D with 3D-CFD Results 3D-CFD Volumetric Flow Head- Distributor Distributor- Bypass Distributor- Cooler 1D-GT-Cool 5% error Distributor- Heater Focus on volumetric flow because of cooling effect Results show good agreement between 3D & 1D (maximum error is ~10%) 9
Variants Which variants were simulated: Engine speed range 1000 rpm 6000 rpm Showing influence on volumetric flow 2000 rpm with closed thermostat Showing influence on volumetric flow Showing influence on flow direction Varying gasket orifice diameter Reaching same volumetric flow passing from block to head Focused cylinder individual Models are easy to modify Savings in computational time compared to 3D-CFD (up to 98% i.e. 50 times faster!) 10
Variants Varying gasket orifice diameter Volumetric Flow Cylinderhead 1 2 3 4 Cylinder No. <Basis Volume Flow Cylinderblock - Cylinderhead <Variant Volume Flow Cylinderblock - Cylinderhead 11
Integration Steps of integration Chosing strategy Integration of GT-Cool & GT-Power Setting Run Set-up criterias Integration Coupling Geometry related Heat transfer related Explicit (GT-Power) Flow control Implicit (GT-Cool) Setting boundary conditions Cooling temperature near target 12
Integration Engine Cylinderhead Cylinderblock Bypass Gasket Integrated simulation model 13
Integration Volumetric Efficiency <GT-Power <GT-Power + GT-Cool Volumetric Efficiency Temperature 1000 2000 3000 4000 5000 6000 Engine Speed [rpm] 3000 rpm Liquid Temperature 3 K 0.5 1 1.5 2 Time [s] Converged Good agreement between both simulations Liquid Temperature at Cylinderhead-out converged 14
Integration Cylinderhead Cylinderhead Temperature Low Piston High Temperature contours plots based on simulation results. Viewing heat transfer in several sections of relevant parts. 15
Conclusion Build & calibrate All parts must be built with equal discretization size Constant gasket orifice discharge coefficients are recomended Intgeration Variants Models are easy to modify Savings in computational time compared to 3D-CFD (up to 98 %) Integration Correct integration of cooling and engine model is sensitive Set right Run-Set up configuration Cooling temperature near target for faster convergence 16
Thank you for your attention! 17