Surface preparation and Boundary Flagging on a Port Fuel Injection (PFI) Engine using Converge Studio
Objective:
To perform surface preparation and boundary flagging tasks on the IC engine case and set up a no hydro simulation
Procedure:
We are likely to get many errors in the design geometry first when importing our geometry and diagnosis in converge CFD. In order to start working on our problem triangle, we flag identifiable limits and cover other parts of the geometry.
Making use of boundary flag option to select the surface to assign them to an individual component say piston and linear etc
The inflow and outflow boundaries are described as circles and oval shapes respectively.
Sometimes the triangles exceed their respective boundaries and spread to other parts in the case make use of boundary fence option to assign fences to individual boundaries and flag them accordingly
1. Boundary Flagging:
After solving the errors the surface must be flagged in order to apply boundary conditions to them
The Individual part of the PFI engine is shown below accordingly
1.Cylinder liner
The cylinder liner, serving as the inner wall of a cylinder, forms a sliding surface for the piston rings while retaining the lubricant within. The most important function of cylinder liners is the excellent characteristic as a sliding surface and these four necessary points.
- High anti-galling properties
- Less wear on the cylinder liner itself
- Less wear on the partner piston ring
- Less consumption of lubricant
2.Piston:
A piston is a component of reciprocating engines reciprocating pumps, gas compressors among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluids in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.
3.Cylinder Head:
In the internal combustion engine, the cylinder head (often informally abbreviated to just head) sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber.
4.The exhaust port:
The passage in the cylinder head which connects the exhaust valve and the exhaust manifold. The exhaust gases pass through the port to the exhaust manifold or header. On two-stroke engines, the exhaust port is cut into the cylinder wall because it does not have valves. Also, see the adjustable variable exhaust port.
5.Total intake port:
The passage in the cylinder head which connects the intake manifold to the intake valve through which the fuel-air mixture proceeds on its way to the cylinders.
6.Intake port -1:
For the simulation, we have divided the Intake port into two parts as follow
1.Intake port - 1.
2.Intake port - 2.
7.Intake port - 2:
8.Intake and Exhaust valves:
There are two types of engine valves intake and exhaust valves. The intake valves, of course, let air in, and the exhaust valves let exhaust air out. The more air you can move air in and out of the engine the more efficient, and therefore power the engine will have.
9.Spark plug:
It is a device for firing the explosive mixture in an internal combustion engine
10.Spark plug terminal:
The top of a spark plug contains a terminal, which serves as a connector to the ignition system. This allows the plug to be used with either connection type. Plugs with a solid terminal, the nut can only be used with the larger, snap-on connector type. The terminal is part of the design of the plug and cannot be removed.
11.The total case setup
Before we move on to set up initial and boundary conditional we have to divide our intake port into two parts because fuel is injection through one half of the intake port and another part has no fuel spray. To initialize the fuel that comes into the combustion chamber.
2.Surface preparation:
The surface preparation error is highlighted as shown below
Intersections errors:
The above picture shows the intersection errors between the valves and cylinder head. To solve this the valves need to positioned perfectly as per the design.
Nonmanifold errors:
The above picture shows the non-manifold problems. These problems usually arise when there are overlapping triangles. Stitching the triangles and deleting the duplicate ones will solve this error
Open Edges :
The above picture shows the open Edges error in Geometry. For a CFD simulation to be done the domain must be closed one. Hence creating or stitching the triangles will solve the errors.
Normal Orientations :
The above picture shows the normal orientation pointing outwards if the fluid flow is inside the normals should point inwards. This error can be solved by changing the normal directions.
Regions and Events:
Boundaries that are assigned to the regions
Cyclic Events
Based on the valve timing for the intake and exhaust profiles we must connect and disconnect from the combustion chamber using the cyclic option in Events box.
Permanent Events
Since we are having regions and the two intake ports 1 and 2 are separated we provide an additional permanent event to it as seen in the image below
Fixed Embedding
Embedding is provided to refine the grid at specified locations to improve the accuracy of our solutions. An embedding for intake and exhaust valve angles provides 0.5 mm cells as mesh refinement.
Embedding for the Exhaust valve:
Embedding for the Intake valve:
Big cylinder Embedding:
Small cylinder Embedding:
An additional embedding is given for our spark plugs so when energy is sourced into spark plug the combustion propagated the embedding can be visualized in the picture given above as small and Big Cylinder embedding with 2 mm and 1 mm cells respectively.
Simulation Time:
Program used 7026.776996 seconds.
Summary of total time for:
load balance = 76.50 seconds ( 1.09%)
solving transport equations = 14.75 seconds ( 0.21%)
move surface and update grid = 4706.01 seconds (66.97%)
update boundary conditions = 418.01 seconds ( 5.95%)
combustion = 0.00 seconds ( 0.00%)
spray = 0.01 seconds ( 0.00%)
writing output files = 1445.02 seconds (20.56%)
Conclusion:
Following all the steps described in our procedure and running the No Hydro simulation, we will end up with the following parameter and animations shown below describing our valve movements defined by their valve timing profiles.
Run parameter for the NO hydrodynamic solver:
The cut plane of the cylinder and the valves are provided as follows
2d No Hydro simulation animation:
No hydro simulation:
No hydro simulation with the valve Movements: