Exhaust Port - Conjugate Heat Transfer CHT Analysis
CHT Analysis
The CHT analysis means Conjugate heat transfer (CHT) which allows the simulation of the heat transfer between Solid and Fluid domains by exchanging thermal energy at the interfaces between them. This requires a multi-region mesh to have a clear definition of the interfaces in the computational domain.
It can accurately predict heat transfer by simultaneous solving all the relevant solid and flow field heat transfer processes, for example conduction through solids, free and forced convection in the gases/fluids and thermal radiation.
The CHT approach has benefits for those applications where heat transfer is either non-uniform or difficult to calculate empirically.
The applications of this analysis is the simulation of heat exchangers, cooling of electronic equipment, and general-purpose cooling and heating systems.
Aim
To perform a CHT analysis on an exhaust port with two different cases.
- Baseline Case
- Refined Case
Geometry
Above is the geometry of the exhaust port used in an inline 4 cylinder engine.
Baseline Case
Mesh Quality
The baseline setup has no inflation layers with an element count of 138831.
Velocity Plot
Above are the two plots with velocity streamline and velocity plane with a velocity of 50 m/s,where all the velocity from the inlets meet at the outlet causing higher velocity at the outlet.
Temperature Contour and Temperature Outer wall Convection
From these plots we can see that the temperature at the outlets are much higher when its compared at the inlets.
The temperature recoreded at the inlets were about 473 K, where as the temperatuer at the starting point of the outlet recorded as 585 k.
Wall Heat Transfer Coefficient
We can see that the heat transfer coefficient is less at the outlet of the outer walls but inside the walls the heat transfer coefficient high.
Refined Case
Mesh Quality
The setup has been refined with body sizing size of 7.5 mm and the Infaltion layer of 5 with maximum thickness of 5 mm. This give as highest elemnt count of 495231 which is close to licensing limit.
Velocity Plot
From the plots we can that the topmost velocity is obtained is at the bend at the outlet of the exhaust port where all the velocity converges at the outlet.
Temperature Contour and Temperature Outer wall Convection
From these plots we can see that the temperature at the inlets are much lesser when its compared at the outlet.
The temperature recoreded at the inlets were about 513 K, where as the temperatuer at the starting point of the outlet recorded as 572 k and the bottom face was 680 K.
Wall Heat Transfer Coefficient
We can see that maximum heat transfer coefficient at the bottom face of the outlet.
Heat Transfer Coefficient Validating
We can validate the HTC by comparing the expermental and analytical values to get the values for HTC.
By improving the mesh and refining it we can validate the results for HTC.
Conclusion
From the exhaust port analysis we can see that there is increase in velocity in the refined case when its compared to baseline case.
Also there signicant change in the inlet temperature in refined case in comparison with baseline case.
Wall Heat Transfer Coefficient is much higher in refined case because of the refinement.