Week 9: Project 1 - Surface preparation and Boundary Flagging (PFI)

Objective: To perform surface preparation and boundary flagging tasks on our IC Engine case and set up a No Hydro simulation.

Procedure:

The PFI geometry .stl file is imported in the Converge Studio. The base geometry has surface errors that need to be cleared before we move up with the simulation.

Geometry:

Simulation error (before case setup):

Boundary Flagging:

To flag the boundaries, we need to create fences across the edges of separating boundaries so it eases the selection of boundaries.

Liner:

Two edges were selected to mark the fence across the Liner edges and the boundary is flagged using the boundary fence method as shown below.

Piston:

The piston is flagged by the boundary fence method as shown below.

Cylinder Head:

Boundary fences are created along the 4 edges which separate the region of the ports & spark plug from the cylinder head region and the cylinder head is extracted as shown below.

Intake Port:

The intake port is split into two boundaries & later into two regions to separate the boundaries for different initial and boundary conditions. The intake port is where fuel spray and the air is injected. A fence is created using a fence between vertices and appropriate boundaries are flagged from the boundary fence method.

Exhaust Port:

The outflow is flagged using the boundary fence method and the rest of the region as outflow as shown below.

Valves:

Intake & Exhaust ports, Liner, and cylinder head are hidden and then valves are visible. The valve geometry is flagged into 3 boundaries. This is done to create the events and ease the creation of disconnect triangles and assign realistic boundary conditions. Also, a translatory motion is provided to these valves by loading the motion files.

Spark Plug & Terminal:

The region where the spark is generated is at a higher temperature than the rest of the spark plug. Hence, two boundaries are necessary to assign appropriate conditions.

Top of Valve top assigned to port boundaries:

Due to the translatory motion of the valves and as it is connected to ports, during movement the surface of the ports gets distorted. To avoid this distortion, the top of the top valves is assigned to the port boundary as shown below.

Flagged boundaries:

Surface Preparation:

Regions:

Regions are created which are used to create events between the zones and to initialize the realistic initial conditions in the flow domain.

Initial and Boundary Conditions:

Case Parameters	Setup
Application Type	Crank angle-based IC engine
Physical Parameters	Cylinder Bore: 0.086m Stroke: 0.09m Connecting rod length: 0.18m Crank speed: 3000rpm
Gas Simulation	Therm.dat uploaded
Reaction Mechanism	Mech.dat uploaded
Run Parameters	Solver - Transient Type - Crank angle-based engine simulation Simulation mode - No Hydro
Simulation Time Parameters	Start time: -480 deg End time: 240 deg
Solver Parameters	Solver Scheme: PISO Type: Density-based

Boundary Conditions:

Piston	Boundary Type - Wall Wall motion - Translating Surface Movement - Moving Law of Wall (Piston Motion) Temperature - 450K (Law of Wall)
Liner	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 450K (Law of Wall)
Cylinder Head	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 450K (Law of Wall)
Exhaust Port	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 500K (Law of Wall)
Intake Port1	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 425K
Intake Port2	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 425K
Spark Plug	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 550K
Spark Plug Terminal	Boundary Type - Wall Wall motion - Stationary Surface Movement - Fixed Law of Wall Temperature - 600K
Intake Valve	Boundary Type - Wall Wall motion - Translating Surface Movement - Moving Law of Wall Temperature - 480K Profile - loaded Minimum Lift - 2e-4m
Exhaust Valve	Boundary Type - Wall Wall motion - Translating Surface Movement - Moving Law of Wall Temperature - 525K Profile - loaded Minimum Lift - 2e-4m
Inflow	Boundary Type - Inflow Temperature- 363K Pressure - 101325 Pa Species - Air
Outflow	Boundary Type - Outflow Temperature- 800K Pressure - 101325 Pa Species - CO2 - 0.192304 H20 - 0.088559 N2 - 0.719137

Regions:

Cylinder Region	Temperature - 1360K Pressure - 185731 Pa Species - CO2 - 0.192304 H20 - 0.088559 N2 - 0.719137
Intake Port 1	Temperature - 390K Pressure - 101325Pa Species IC8H18 - 0.025508 O2 - 0.20157 N2 - 0.77292
Intake Port 2	Temperature - 370K Pressure - 101325Pa Species - Air
Exhaust Region	Temperature - 1360K Pressure - 185731 Pa Species - CO2 - 0.192304 H20 - 0.088559 N2 - 0.719137

Events:

Cyclic	Between Cylinder region & Intake Port 1, Period -720 deg, Event - Valve Between Cylinder region & Exhaust Region, Period -720 deg, Event - Valve
Permanent	Between Intake Port 1 & Intake Port 2, Event -Open

Mesh Size:

Here the base grid of 0.004m is used along with the fixed embedding. For the Intake and Exhaust valve angle scales of 3 and 1 embedding layer is used with Permanent Mode. Whereas, for the Cylinder region and zones next to the valves in the ports a cylinder entity is used with a scale of 2 & 1, respectively.

Results:

The results are processed for No-Hydro simulation and the grid size is coarsened by a factor of 4 (n = -2) as the computation time was too high for the fine mesh. The grid was coarsened as it was only a no-hydro simulation. The simulation took 263 sec while running with 6 processors.