silencer using co-simulation Presented by: Ayyoob Zarmehri STAR - PowerPoint PPT Presentation

Thermal soak simulation of Scania’s Eu6 silencer using co-simulation Presented by: Ayyoob Zarmehri STAR Global Conference Vienna 2014 SCANIA CV AB  Vehicle cooling and aerodynamics   Underhood thermal management Ayyoob Zarmehri STAR Global Conference 18/3/2014 1

Underhood thermal management  5 CFD engineers  Technical advices for different design and test groups  Full truck simulation :  All external surfaces of different parts  Heat exchangers like radiator, charge air cooler  Fan installation  Conjugate heat transfer for parts of interest if needed Ayyoob Zarmehri STAR Global Conference 18/3/2014 2

Silencer function Sound absorber  Lowering emission level, satisfying Eu6 standard:  Inside needs to be hot enough for the chemical factory to function properly  Requirements regarding the temperature of the external surfaces  Heat sensitive sensors  Heat management is necessary to handle the situation  Ayyoob Zarmehri STAR Global Conference 18/3/2014 3

The structure of the silencer  Polyhedral mesher  Embeded Thin mesher  35 million cells mesh Ayyoob Zarmehri STAR Global Conference 18/3/2014 4

The thermal soak process Both the energy source and the cooling airflow are off  Inherently transient process  Complex function of heat conduction, natural convection and radiation  Difficult to test experimentally  Need to know the correct amount of energy stored in the system  The interaction between the external flow and the system needs to be  known One steady-state simulation is needed for the initial conditions  Ayyoob Zarmehri STAR Global Conference 18/3/2014 5

The steady-state co-simulation Heat transfer coefficient and the reference temperature is exported Temperature is exported to the UTM simulation Simulation 1: Simulation 2:  Internal flow  The external flow  Heat conduction within Solid  Truck speed: 30 km/h structure  Steady-state  Steady-state  Radiation included Ayyoob Zarmehri STAR Global Conference 18/3/2014 6

The natural convection simulation Test cases: flat plate of constant temperature in room temperature  Case 1: horizontal plate with upper side heated  Case 2: horizontal plate with lower side heated  Case 3: vertical plate  Physics modeling: density as a polynomial function of temperature  Coupled solver  Different turbulence models were tested:  Standard K-E Low-Re:  quadratic constitutive relation  thermal stratification for buoyancy production of dissipation  K-E two layer  buoyancy driven formulation  Best results for a wide range of temperature difference : Standard K-E Low-Re  Ayyoob Zarmehri STAR Global Conference 18/3/2014 7

Test cases: flat plate in different orientations The natural convection simulation The near wall mesh Vertical plate Horizontal plate, velocity Horizontal plate, wall Y+ Ayyoob Zarmehri STAR Global Conference 18/3/2014 8

The natural convection simulation Experimental values for:  Flat plate with dimensions of 0.6m × 0.6m  Ambient temperature: 30 °C Ayyoob Zarmehri STAR Global Conference 18/3/2014 9

The thermal soak simulation  Solid simulation:  Leading simulation  Unsteady  Time step: 5 s  Coupling time step: 150 s  Radiation included  Fluid simulation:  Lagging simulation  Initial conditions calculated  Steady-state  Iterations per exchange: 200  Exports: Specified Y+ HTC and Reference Temperature Ayyoob Zarmehri STAR Global Conference 18/3/2014 10

Conclusions: Thermal soak simulation has been successfully accomplished with co-  simulation Transient cooling of the solid mass is coupled to quasi-steady state changes of  the external natural convection flow Co-simulation provides an easy-to-use communication method between two  different simulations Future works: Urea spray simulation  Calibration with experimental results  Ayyoob Zarmehri STAR Global Conference 18/3/2014 11

Thanks for the attention! Questions? Ayyoob Zarmehri STAR Global Conference 18/3/2014 12