Converge CFD

CAT3410 Engine simulation using Converge CFD

OBJECTIVE-To run simulations for two types of pistons for diesel engine CAT3410 and characterize the emissions (Soot, Nox and UHC).

Geometry-A 3d geometry of Port fuel injection engine was imported to converge for analysis.

Make Engine Sector Surface:

Using the make surface utility in converge studio both the open W sector and omega sector of piston was extracted.

Open W Piston Profile:

Omega Piston Profile:

Geometry for Open W Piston:

Geometry for Omega Piston:

Setup-

Application Type-

Crank angle-based IC engine

Physical Parameters:

  1. Bore =0.13716 m
  2. Stroke = 0.1651 m
  3. Connecting rod length = 0.263 m
  4. RPM = 1600

Materials-

Gas Simulation- The therm.dat file was uploaded to get the thermodynamic properties of the fuel.

Parcel Simulation- C7H16 was selected from predefined liquids.

Reaction Mechanism

Species-Parcel C7H16(n Heptane)

Mesh-

Simulation Time Parameters:

Run Parameters:

Transient,Full hydrodynamic.

Simulation Time Parameters:

  1. Start time : -147 deg
  2. end time : 135 deg
  3. Initial time step:5e-7  ,Minimum time step:1e-08 ,Maximum time step:2.5e-5

Boundary Conditions:

Boundary Type-WALL , Wall motion-Translating and Surface-Moving

Law of wall for velocity & temperature boundary conditions

  • Piston-Velocity-piston motion, temperature – 553K

Boundary Type-WALL , Wall motion-Stationary and Surface-Fixed

Law of wall for velocity & temperature boundary conditions

  • Cylinder wall – 433 K
  • Cylinder Head-523 K

Boundary Type-Periodic , Periodic Type-Stationary and Periodic Shape-Rotational-45 deg

  • Front Face & Back Face

Regions and Initial conditions:

Physical models:

Spray Modelling:

-Frossling model

-collison model-NTC collision,collision outcomes-Post collison outcomes

Injection Parameters:

  1. Total injected mass = 2.70167e-5 Kg
  2. Injection start time = -9.0
  3. Injection duration = 21
  4. Fuel temperature = 341K
  5. Total number of injected parcels per nozzle=50000

Rate shape implementation:

Combustion Modeling:

Sage Model:

Turbulence Modelling:

RANS k-epsilon RNG model

Grid Control:

Base Mesh- dx=dy=dz=0.004m

Adaptive Mesh Refinement:

Velocity Adaptive Mesh Refinement

Temperature Adaptive Mesh Refinement

Animation of Adaptive Mesh Refinement:

Fixed Embedding:

Nozzle

Sequential,Scale-2

Boundary Embedding

Piston-Sequential, Scale-1, embed layers-1

Boundary embedding-

cylinder head-Sequential, Scale-1 ,Embed layers-1

 

Results-

Analysis for Open W and Omega Piston 

Pressure Vs Crank angle:

From the below figure we can see that the peak pressure for open W piston is higher than the omega piston.

Mean Temperature Vs Crank angle:

From the below figure we can see that the peak mean temperature is significantly lower for open W piston and the omega piston is having a higher peak mean temperature. This might be an indication that the fuel is not burnt properly in case of open W piston.

Integrated Heat Release rate:

From the below figure we can see that the integrated heat release rate is lower in case of open W piston. At at the end we can see that the total heat release is less in open W piston. That means for same amount of fuel injection we are getting less heat output for open W piston.

So from the above graph the heat release for Omega piston is 7279.46 J and open W piston is 7211.73 J

Lower heating value(LHV) of C7H18=42.78 MJ/kg

The difference is 67.73 J per cycle.

Mass of fuel required for 67.73 J=67.73/42.78*10^6=1.6e-6 kg

Mass of fuel required for 67.73 J for 1000 cycles=0.0016 kg

So 0.0016 kg mass of fuel wasted for Open W piston configuration for 1000 cycles.

Emissons analysis for Open W and Omega Piston 

Comparision of Soot formation:

Open W piston has more soot formation than omega piston

Comparision of NOx formation:

From the below graph its seen that open W piston has very low NOx emissions as compared to Omega piston which is also indicated by the low temperature is our earlier analysis.

Comparision of CO formation:

From the below graph its seen that open W piston has more CO emissions which signifies that there is unburnt fuel for open W design.

Comparision of CO2 formation:

CO2 formation is more in case of Omega piston.

Comparision of Unburnt hydrocarbon:

From the below graph its clear that unburnt fuel is significantly higher in case of open W piston.

Animation:

Animation of temperature variation in engine

Animation:

From the animation we can clearly see that NOx emissions is more in Omega piston

Animation:

From the animation we can clearly see that soot emissions is more in open W piston.

IMEP and Power Calculation:

From the engine performance calculator the following results were obtained:

For Open W Piston:

INDICATED MEAN EFFECTIVE PRESSURE(IMEP)=1.24e+6 pa

Speed of engine=1600 rpm

=1600/60=26.66 rps

Speed in degree/second=360*26.66=9597.6 degree/s

270.156 deg duration in seconds=270.156/9597.6=0.0281 s

Gross Work=3028.53 J

Power=3028.53/0.0281=107.7 KW

For Omega Piston:

INDICATED MEAN EFFECTIVE PRESSURE(IMEP)=1.39e+6 pa

Speed of engine=1600 rpm

=1600/60=26.66 rps

Speed in degree/second=360*26.66=9597.6 degree/s

270.156 deg duration in seconds=270.156/9597.6=0.0281 s

Gross Work=3409.28 J

Power=3409.28/0.0281=121.3 KW

CONCLUSION:

Simulations for two types of pistons for diesel engine CAT3410 was performed and following conclusion is drawn.

1. The peak mean temperature is significantly lower for open W piston and the omega piston is having a higher peak mean temperature which indicates there is unburnt fuel.

2. The integrated heat release rate and power output is lower in case of open W piston.

3. Open W piston has very low NOx emissions as compared to Omega piston.

4. Open W piston has more CO emissions which signifies that there is unburnt fuel for open W design.And it is confirmed as the soot production is more in open W piston.

5. CO2 emissions are more in case of Omega piston.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *