Week 10: Project 1 - FULL HYDRO case set up (PFI)

Hello,

In this PFI SI Engine challenge (Hydro-mode), as per the given problem statements, first we find the respective parameters to set our case setup accordingly and plan the simulation. To do the same, first go for importing the geometry in CONVERGE-STUDIO. After this, go for the normal checks, which must be pointed in the direction of the flow. Then, a diagnosis is done to check for any kind of geometrical error. During this, several problems are coming up with the model that must be corrected. that can be done by using the patch, del, normal, etc. commands. But the main problem is that the geometry is very complex, so it's better to flag boundaries first to do the diagnosis more efficiently. After boundary flagging, select each surface individually and work over the problems one by one. The main problem during the boundary flagging comes when the inlet valve is overlapped with the inlet port. So that can be corrected by pushing the valve a little downward in the direction of its axis. After verifying it, the case setup is set as per the given inputs and boundary conditions. In this case, all the basic parameters are selected with specific values, and all these values are setup together as input files for the model. So it is important to set the simulation to "hydro mode". Now extract the input files.

The simulation that follows can be converging by using the Cygwin interface, which is required for giving the command to the software. In Cygwin, first we go to the directory where the input files are present and then command them for simulation. This simulation can be done automatically at the back end, and the output files are generated in the same folder as the results of the simulation.

Then those output files have to be exported in Paraview to see the results in the different interfaces and also in their plots in the Converge Studio. For importing the output files in Paraview, first we need to convert the data into a ".vtm file," which is done in the "Post-Processing 3-D" option in Converge-Studio. Then all the 3D and 2-D analyses of the results are analyzed separately. The rest of the plots can be seen in Converge-studio itself, specifically under the "line-plotting option."

By doing so, I was able to obtain all of the required results for this particular challenge and take screenshots of them. The CFD analysis of this problem is done three times for three different mesh sizes, and the results are attached in a word file. Kindly find it below.

As we see in the attached results word file. It is notice that the combustion pressure is usually observed at its peak at TDC, but here it is postponing some crank angle in the forward direction. This is because of the lag and the time that fuel takes to breakdown properly. Hence, that is the main reason the pressure and temperature trends are like that. As we run about 2 cycles, the pressure and temperature of the second cycle are higher than the first cycle because the initial condition is also included in the second cycle and is much higher than the preset value that we set typically during the case setup.

Hence, due to that NOx trend, they are also similar. As the NOx is a cylinder-temperature-dependent quantity, it rises in the second cycle.

1* The compression ratio of the SI Engine is set on 8. This can be done under the option of "Crank angle-based". First check the piston is at the BDC then select all the cylinder components or those which are attached directly to cylinder portion and then slect the piston head. After that choose the compression ratio and set by appling it.

2* We need a wall heat transfer model because the model is already very complec and for predicting the wall temprature via CFD will become more complex and approximately 5 times more bulkier. This is because we need to simulate all the surrounding envirnment also for doing the same. Hence we go for suitable model to get results.

3* Combustion efficiency is the ratio of the energy genrated by the fuel during combustion to available chemical energy that is present in the fuel. SO the available chemical energy is the calorific value of the fuel times the mass of fuel injected i.e. 47893*3e-05 KJ.Kg2. Engine output is Workdone by time taken to complete stroke i.e. 1241 MJ * 750 deg. So we are getting Combustion efficiency about 42.4445%

4* Power is the gross work genrated during the cycle to the time taken for the stroke. so we get power 1.67 kW and torque we get is 531 Nm.

5* The crank angles of 10%, 50%, and 90% of the maximum cumulative apparent heat release are designated as CA10, CA50, and CA90, respectively.

Thank you

Anubhav