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

Objective: The objective of the challenge is to run a transient state simulation on the given Port Fuel Injection engine. Here we need to create the surface preparation for each and every object present in the geometry and at the same time, we need to flag them with proper regions and boundary conditions. Here we need to set up the full hydro case by using the given boundary conditions and to discuss the results.

Introduction:

Multipoint fuel injection devotes a separate injector nozzle to each cylinder, right outside its intake port, which is why the system is sometimes called port injection. Shooting the fuel vapor this close to the intake port almost ensures that it will be drawn completely into the cylinder. The main advantage is that MPFI meters fuel more precisely than do TBI designs, better achieving the desired air-fuel ratio and improving all related aspects. Also, it virtually eliminates the possibility that fuel will condense or collect in the intake manifold. With TBI and carburetors, the intake manifold must be designed to conduct the engine’s heat, a measure to vaporize liquid fuel.

This is unnecessary on engines equipped with MPFI, so the intake manifold can be formed from lighter-weight material, even plastic. Incremental fuel-economy improvements result. Also, where conventional metal intake manifolds must be located atop the engine to conduct heat, those used in MPFI can be placed more creatively, granting engineers design flexibility.

Diagnostics:

• When we imported the .stl file into the converge GUI, initially it shows a lot of errors like Intersection, Non-manifold problems, open edges, overlapping triangles, and normal orientation errors.
• To overcome these all errors we need to make reasonable modifications to the geometry without losing its originality and what it made for.
• We take the action called 'Fence' to flag the boundaries which are important steps to overcome the errors.

Fence:

In some cases, particularly in this, the triangles exceed their respective boundaries and spread to other parts. To control this we need to use a boundary fence option. There are two types in the fence.

Boundary Flagging:

This operation is essential to the proper configuration of almost every simulation. After properly flagging boundaries, you can easily assign motion properties, initial conditions, connect/disconnect regions, and other parameters of the simulation to the different geometry boundaries.

• Have a total of 16 boundaries which has been flagged for the simulation.

• Here in the above picture, we can see the liner, cylinder head, intake port (it has been divided into two parts), inlet, and outlet.
• Because of solid parts, we cant able to see the spark plug, sparkplug terminal, Intake valve, and exhaust valves.

Piston:

The piston is a component of the internal combustion engine. The main function of the piston is to transform the pressure generated by the burning air-fuel mixture into force, acting on the crankshaft.

After the piston compresses the fuel-air mixture, the spark ignites it, causing combustion. The expansion of the combustion gases pushes the piston during the power stroke.

Passenger vehicles have aluminum alloy pistons while commercial vehicles can also have steel and cast iron pistons.

• Here we are considering the piston as just a moving plate that will move from top to bottom and covers a total of 720 degrees crank angle. It is guided by the cylinder liner.

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.

1. High anti-galling properties
2. Less wear on the cylinder liner itself
3. Less wear on the partner piston ring
4. Less consumption of lubricant

Cylinder Head:

The cylinder head is an integral component of internal combustion engines. It conveys air and
gasoline to the combustion chamber and serves as a cover for the cylinders. The main function of the cylinder head is to help the head gasket seal the cylinders properly so that they are able to build enough compression for engine operation. In the vast majority of four-stroke engines, the cylinder head mounts the entire valve gear and provides the basic framework for housing the gas-exchange valves as well as the spark plugs and injectors. It also supports the different parts of the cooling system.

The cylinder head must be strong and rigid to distribute the gas forces acting on the head as uniformly as possible through the engine block. The combustion gas, the coolant, and the lubricating oil flow independently in the cylinder head and follow complex three-dimensional routes. Thus cylinder heads are generally produced by gravity or low-pressure die casting.

Intake Port:

In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders.

The primary function of the intake manifold is to evenly distribute the combustion mixture (or just air in a direct injection engine) to each intake port in the cylinder head(s). Even distribution is important to optimize the efficiency and performance of the engine. It may also serve as a mount for the carburetor, throttle body, fuel injectors and other components of the engine.

• We have divided the intake port into two parts: Intake port-1 and Intake port-2.
• This is because we are providing the vapors in this region - IC8H18 - (violet region - Intake port 2). The temperature in this region is 20 degrees higher than in the Intake port-1.
• In the Intake port-1 (Ash colored region), we only give the pure air which contains 23% Oxygen and 77% Nitrogen.

Exhaust Port:

The exhaust port is a passage in the cylinder which transports spent and burned mixture from the cylinder into the exhaust pipe. The exhaust port window is the actual opening in the cylinder bore, which is opened and closed by the movement of the piston.

In two-stroke engines, moving the top edge of the exhaust port window towards the cylinder head is called "raising the exhaust port." This advances the port timing by making the exhaust port open earlier in the downward stroke of the piston which helps the exhaust gas to escape more quickly. If you raise the exhaust port too much, the gases will escape too early to give the piston the maximum amount of push.

Valves:

Engine valves are mechanical components used in internal combustion engines to allow or restrict the flow of fluid or gas to and from the combustion chambers or cylinders during engine operation.

Modern gasoline engines with 4-valve cylinder often use a pentroof shaped combustion chamber that allows the valves to be oriented at an angle to the cylinder axis. This allows them to use a larger diameter valve and achieve a higher valve flow area than a similar-sized diesel engine.

The valves used in the IC engines are of three types: Poppet, mushroom valve, Sleeve valve, or Rotary valve. Of these three types, the Poppet valve is most commonly used.

• There are a total of 4 valves, two are (Yellow) Intake valves and another two are (Red) are exhaust valves.
• Intake valves help in providing the air to the combustion chamber by lifting upside. Exhaust valves are used to let the burnt gases out by lifting upwards from the combustion chamber after combustion happens.

Spark Plug:

Spark plug, also called Sparking Plug, device that fits into the cylinder head of an internal-combustion engine and carries two electrodes separated by an air gap, across which current from a high-tension ignition system discharges, to form a spark for igniting the air-fuel mixture.

Spark plug terminal:

System connection. Spark plug insulated center electrode is connected by a heavily insulated wire to an ignition coil or magneto circuit mounted external to the engine. The spark plug body forms a grounded terminal on the base of the plug on the cylinder head, with a spark gap inside the cylinder.

• The temperature difference between the spark plug and its terminal is the must criteria you must check before running the simulation.
• Here in this case the temperature difference is 50 degrees.

Surface Preparation:

Intersections:

• The intersection errors refer that our triangles are not connecting with the other triangles, instead, they are an irregular shape and causing open edges.
• Here, in this case, we have 1574 intersection errors at the inlet valve area. There the triangles are out of the shape and intersecting with one another which is a bad case.

• This error zone is predicted by the diagnostics option. In that option, we need to just click the show button to view where the intersections are.
• To prevent these types of errors, we need to move the geometry of the cylinder (pushed downward) gently.
• This is done in the translate options by taking the arc normal of the valve at the top of the valve circle. After hitting the Apply, the valve top, angle, and bottom automatically moved downward to 0.1 mm and the intersection errors are gone.

NonManifold errors:

• A non-manifold geometry is a 3D shape that cannot be unfolded into a 2D surface with all its normals pointing the same direction.
• These types of errors can be fixed easily by just deleting the triangle that manifolds with another triangle.
• We just need to delete that triangle and stitch the middle triangle with the other triangle. Then we need to fill the gap by using a Hot Keyword T (T means filling a triangle).

Open Edges:

• The open edges errors are straight errors, that have a hole in the geometry. It can be easily predicted and fixed.
• To fix these types of errors we need to go to the Repair, then Patch by selecting the open edge.

• After doing the patchwork in the Repair option, the geometry looks like:

Overlapping Errors:

• These are just the triangles that overlap with each other.
• Overlapping errors are needed to be fixed by deleting the particular triangles and then refixed them by patching the empty area with the triangles.
• But in this case, the overlapping errors are connected to the normal orientation error. So, if we fix the normal orientation of the fluid flow, then overlapping errors get diffused automatically.

• By translating the normal direction of the whole geometry, the errors get reduced.

Normal Orientation:

• Normal is a vector that is perpendicular to the surface of an object

• Here we can clearly see the error, that pistons normal direction is wrong, flow direction normal is wrong. It all gets fixed by translating the normals.
• But initially, in the geometry, it is provided with a reverse normal direction, we get fixed this by translating the normals only.
• It is fixed by, going to Translate, then to normal. Select any triangle and just hit the Apply or enter button to fix this.

The Final Product: (Surface cleaned, Prepared and Boundaries flagged)

• After cleaning all the errors from the surface of the given geometry and fixed all the overlapping and normal directional errors, the geometry looks like.
• The figure showed below is divided by the help of the region zone.

Setup:

1. Engine Specifications:

Bore =0.086 m

Stroke = 0.09 m

Connecting rod length = 0.18 m

RPM = 3000

2. Materials:

Parcel simulation

• Liquid name: IC8H18

Reaction Mechanism

• Available elements: 4
• Available species: 48
• Available reactions: 152

Species

• Parcel: IC8H18

3. Simulation Parameters:

Run Parameters

• Solver: Transient
• Simulation mode: Full hydrodynamic

Simulation time parameters

• Start time: -480 deg
• End time: 120 deg
• Min. time step: 1e-8 s
• Max. time step: 0.0001 s

Solver parameters

• N-S solver type: Density-based
• N-S solver scheme: PISO

4. Boundary Conditions:

• Temperature limits we have provided for the respective parts in the geometry are:

1. Piston temperature - 450K
2. Liner temperature - 450K
3. Head temperature - 450K
4. Spark Plug temperature - 550K
5. Spark Plug electrode temperature - 600K
6. Exhaust ports temperature - 500K
7. Exhaust outflow - 1 bar
8. Exhaust outflow temperature - 800k
9. Exhaust species concentration - Calculate the stoichiometric condition
10. Exhaust valve top temperature - 525K
11. Exhaust valve angle temperature - 525K
12. Exhaust valve bottom temperature - 525K
13. Intake port - 1 temperature 425K
14. Intake port - 2 temperature 425K
15. Inflow pressure - 1 bar total pressure
16. Inflow temperature - 363K
17. Inflow species - Air
18. Intake valve top temperature - 480K
19. Intake valve angle temperature - 480K
20. Intake valve bottom temperature - 480K

• For each and every boundary flagged, the wall heat transfer model is applied.

5. Regions:

• We provided the regions in the regions and initializations so that we can use them in the boundary flaggings.
• Actually the regions are the volumes that we created inside the geometry so that the simulation or reaction happens.

• We created four regions inside the geometry to happen the combustion:

1. Intake Port - 1 (closer to the combustion chamber)

• ic8h18 - 0.025508
• o2 - 0.20157
• n2 - 0.77292
• Temperature - 390k
• pressure - 1 bar

2. Intake port - 2 (far from the combustion chamber)

• Air

• Temperature - 370K
• Pressure - 1 bar

• Cylinder
  • Pressure - 1.85731 bar
  • Temperature - 1360K
  • Stoichiometric composition

3. Cylinder region

• Co2:0.19
• H2O: 0.08
• N2: 0.71
• Temperature: 300 K

4. Exhaust region

• Co2:0.19
• H2O: 0.08
• N2: 0.71
• Temperature: 1360 K

6. Events:

• Use the Events dialog box to create custom events in certain boundaries or between two or more regions at defined intervals. Because CONVERGE cannot properly execute a simulation if surface triangles from two boundaries intersect, using the Events section is the only way to discontinue (or allow) flow between two regions.
• Click the Add button to create a new row in the Events table. If you enable Events, you must create an event between each pair of adjacent regions, or CONVERGE will produce an error message. Table 3.50 describes the temporal and event types.

• Here the selected event is Valve. The function of the valve is

1. VALVE: Automatically create OPEN and CLOSE events. Timing is automatically pulled from valve lift profiles specified in the Boundary dialog.

7. Physical Models:

Spray Modelling

(A) General:

• Evaporation model: Frossling model
• Evaporation source: source all base parcel species

(B) Collision/Break/Drag

• Collision model: NTC collision
• Level of mesh for collision: 2
• Drop drag model: Dynamic drop drag

(C) Injector

Add an Injector to the list and do necessary edits to it.

• Injector_0
• Model: KH+RT
• Nozzles: 4

Injector_0 Configuration

(a) Rate Shape:

• We need to create a profile of how the nozzle has to spray the fuel. This is called the Rate shape.

(b) Models

• The spray breakup models used in the simulation are Kelvin-Helmholtz (KH) and Rayleigh Taylor (RT).
• We have set the recommendations for the Gasoline PFI.

(c) Time/temp/Tke/Esp/Mass/Size

• Injection temporal type: Cyclic
• cycle period: 720 deg
• Start of injection: -480 deg
• Injection duration: -191.2 deg
• Total injected mass: 3e-5 kg
• Total injected parcels: 50000

• Due to the evaporation model is applied we can't get the total 50000 spray parcels. The above picture is after running the case picture.

(d) Injection Parameters

• Fuel flow rate = 7.5e-4 Kg/second
• Injection start time = -480.0
• Injection duration = 191.2
• Fuel temperature = 330K

(e) Nozzles (Configuration & Positions)

• Nozzle location and orientation: Cartesian
• Injection spray type: Solid cone type

• Nozzle diameter = 250 micro-meter

• Circular injection radius = Nozzle radius

• Spray cone angle = 10

• Here also we need to add a total of 4 nozzles at the Intake port-1

1. Nozzle-0

• center 0.0823357 0.00100001 0.07019
• Align Vector -0.732501 0.210489 -0.647408

2. Nozzle-1

• center 0.0823357 -0.00099999 0.07019
• Align Vector -0.732501 -0.210489 -0.647408

3. Nozzle-2

• center 0.0823357 -0.0004 0.07019
• Align Vector -0.5 -0.2 -0.647408

4. Nozzle-3

• center 0.0823357 0.0003 0.07019
• Align Vector -0.5 0.2 -0.647408

After setting up the nozzles configurations and their positionings, the nozzle look like:

Combustion Modelling:

(A) General

• Temporal type: Cyclic
• Cyclic period: 720 deg
• Start time: -170 deg
• End time: 130 deg
• Combustion temperature cutoff: 600
• Min. HC species mole fraction: 1e-08

(B) Models

• Model: SAGE

Turbulence Model:

Model: RNZ - Kepsilon

Source/Sink modeling:

• The source/sink modeling is, we have to create a source of energy that can be generated from the energy equation in the background coding.
• This source/sink energy we are using in between the two terminals of the spark plug.
• We have to provide the heat source there because software expects this operation from the user.
• Here, we are including the 2 sources.

1. Source1:

• Source type: Energy
• value: 0.02 J
• Total time: -15 to -14.5 deg's (Means 0.5 deg)
• At this small time period of 0.5 deg, the total power is 0.4J, because the other source effect will upon this.

2. Source1_copy:

• Source type: Energy
• value: 0.02 J
• Total time: -15 to -5 deg's (Means 10 deg)

8. Grid Control:

Base Grid:

• dx: 0.004m
• dy:0.004m
• dz:0.004m

Adaptive Mesh Refinement:

AMR Group1:

• Active regions: Intake port-1, Intake port-2, cylinder region
• Velocity:

1. Embedded type: SGS
2. Max. embedded level: 3
3. Subgrid criterion: 1.0

AMR Group2:

• Active regions: Intake port-1, Intake port-2, cylinder region
• Temperature:

1. Embedded type: SGS
2. Max. embedded level: 3
3. Subgrid criterion: 2.5

Fixed Embedding:

• Fixed embedding makes the mesh finer at the specified locations to increase the accuracy of the solution.
• As discussed in the video lectures, the intake and exhaust valve angles provide 0.5mm cells as mesh refinement.

(A) Intake and Exhaust valve angles

• Scale: 3
• Embedded layers: 1
• Mode: Permanent

(B) Big and Small cylinders

• Scale: 1
• Mode: Permanent
• Centers of Big cylinder: (0,0,0.08)(0,0,-0.15) all units in Meters
• Centers of Small cylinder: (0,0,0.018)(0,0,-0.15) all units in Meters

(C) Spherical Embedding (for spark plug)

• Scale: 5
• Start time: -16 deg
• End time: 7 deg
• Centre: (-0.003,0,0.00915) M
• Radius: 0.001

(D) Large Sphere

• Scale: 3
• Start time: -16 deg
• End time: 7 deg
• Centre: (-0.003,0,0.0091) M
• Radius: 0.003

(E) Injector Embedding

• Scale: 4
• Start time: -482 deg
• End time: -286 deg
• Radius 1: 0.002 m
• Radius 2: 0.004 m
• Length: 0.02 m

9. Output/Post-processing

(A) Output files

• The time interval for writing 3D output data: 2.0 deg
• The time interval for writing restarting files: 10.0 deg
• The time interval for writing text output: 0.1 deg

Results:

Valve and Piston Movement: https://youtu.be/ImlklVTsHrQ

• From the above animation, we can see the movement of all four valves, intake and exhaust valves are moving one after another with respect to the crank angle given.

Mesh:

CONVERGE automatically generates an optimized Cartesian mesh at runtime and dynamically refines the mesh throughout the simulation using AMR. All of this remains the same in CONVERGE 3.0, and you can still use meshes exactly as they were in all previous versions of CONVERGE.

CONVERGE’s innovative Adaptive Mesh Refinement (AMR) technology automatically adjusts the grid at each time-step, adding cells in areas with complex phenomena and eliminating cells that are not needed to yield accurate results. This strategic refinement ensures that CONVERGE can resolve flame fronts and high-velocity flows while minimizing the overall cell count.

Spray Particles:

• The spray parcels or particles we are provided initially are 50000. These spray particles came from the four nozzles we have created near the Intake port side.
• There will be a chance of getting an inaccurate number of spray particles, because of the vapourization, unburnt species, and some other phenomena.

• Here in the above graph, it shows jow manty spray particles have participated at the respective crank angle.
• At the crank angle of -186.6 deg, the intake ports get fully opened, and there we can see the max. spray particles.
• There is a reduction in the spray particles as the crank angle increases. This is because the combustion has happened and spray particles get evaporated.
• Approximately 42500 spray particles only participated in the combustion. We have two reasons for that:

1. On the way from the spray nozzle to the combustion chamber, there is a difference in the temperature. Due to this, we may haven't got the total number of 50000 particles.
2. The other reason is when the intake port is getting closed, some spray particles are trapped and get unburned. This phenomenon is visualized in the below video after the intake ports get closed.

Spray Particles Animation: https://youtu.be/Inctxc80RGk

Temperature:

• When we start the simulation, at the initial stage the whole process is at the exhaust position. This is the reason for the temperature hike at the initial stage.
• At the start, the temperature is at 1360 deg centigrade, which is purely a temperature boundary condition of the exhaust region.
• In the graph in the region of -300 to -100 deg, the process is at the almost same temperature. The reason for this phenomenon is it is the air suction process.
• Characteristics immediately after the 0 deg if we see, there is a sudden rise in the temperature. The reason for this phenomenon is because in this region we are going to ignite the fuel inside the chamber with the help of source term given to the spark plug.
• The complete combustion or maximum temperature recorded is 2483.5 degrees centigrade.

Temperature animation: https://youtu.be/u5yfPmB8Uyo

Pressure:

• Because of the slow flame propagation rate, buoyancy causes the hot combustion products to rise relative to the environment during flame propagation.
• The combustion process increases the internal energy of a gas, which translates into an increase in temperature, pressure, or volume depending on the configuration. In an enclosure, for example, the cylinder of a reciprocating engine, the volume is controlled and the combustion creates an increase in pressure.
• The Max. pressure recorded is 3.9 bar, and that degree of the crank angle the combustion happens.

Pressure Animation: https://youtu.be/Zg4OI5mj5M0

Velocity:

• Initially before the opening of the intake ports, the velocity of the particles is not there. But once the intake ports opened, the velocity change of the species is clearly observed.
• Before the opening of the intake ports, the velocity is below 100 m/s. After the intake ports get opened the velocity raised up to 200 m/s because of the sudden pressure drop by increasing in the surface area.
• The max. temperature recorded is up to 440 K at the place of the exhaust region At the starting of the video. Actually the process is in exhaust process at the starting of the video.

Velocity Animation: https://youtu.be/-unWbyu2gHc

Mass Fraction of IC8H18:

• The mass fraction of the IC8H18 is quite grounded (means almost 0 kg) from the -520 to -450 deg.
• From there the suction stroke has begun, so the Nozzles spray the spray particles of the IC8H18 liquid.
• At the energy releases from the spark plug at the -5 deg region, all the spray particles get disappear or evaporates and converted into the burnt gases.
• The maximum weight of the spray particles is around 3.2e-05 kg.

Mass fraction Animation: https://youtu.be/7qtFWsO7jZE

CO2 Mass fraction:

• Carbon dioxide is the principal product of the combustion of fossil fuels since carbon accounts for 60–90 percent of the mass of fuels that we burn.
• Here the amount of Carbon Di-Oxide produced after the combustion happens is nearly 8e-05 kg.

CO2 Mass fraction Animation: https://youtu.be/IAAIFxT9_Go

1. What is the compression ratio of this engine?

• The above plot shows us how the piston creates the volume inside the cylinder. The crests and troughs describe the four strokes of the PFI engine.
• The formula to find out the compression ratio of the engine is

Compression ratio = `(Highest. Volume)/(Lowest. Volume)`

Highest or Maximum volume = 0.000562362 m^3

Lowest or Minimum volume = 0.0000560296 m^3

Compression ration = 10.03

2. Why do we need a wall heat transfer model? Why can't we predict the wall temperature from the CFD simulation?

• The simulation actually takes a huge time to complete because, in the simulation, we have included several models like fluid flow, turbulence, reaction mechanism, combustion modeling, spray modeling, and injection characteristics, etc.
• Here in the geometry, we actually took the fluid domain only and neglected the solid domain. It means the solid parts or solid geometries were not modeled.
• If the solid domains or geometries were modeled, the computer takes a huge amount of time or the solution may get crashed.
• Even if we modeled the solid domains or geometries, there will be a complex type of intersection and overlapping errors in the geometry, mostly at the intake and exhaust ports which are difficult to handle.
• If we take the spark plug, it gives the flame which is near the wall and the heat transfer between the flame and wall of cylinder head takes place. But here physical properties of cylinder-head wall is absent.
• So, as the complex intersections are there inside the regions with the absence of physical properties for the walls, it is not a good idea to calculate wall temperatures based only on the CFD (Navier-Stokes) equations.
• So that the wall heat transfer models are used to predict the wall temperatures.

3. Calculate the combustion efficiency of this engine

• As there are some physical losses in the experimental engine, there are some other chemical losses in the simulation.
• The total amount of fuel sprayed by the ports was not converted during the combustion process.
• Some of the fuel gets unburnt so that the difference in the efficiency is recorded. By using the total Heat released at the time of combustion we can calculate the engine efficiency.
• A total of 1241.16 J of energy is released from the combustion process alone.

Combustion Efficiency = Total Heat Released / Total Energy content of the fuel

`eta_(comb)` = Integrated Heat Release / m*LCV(lower calorific value of fuel)

Here, Integrated Heat Release = 1241.16 J

Mass of the fuel-injected, m = 3.0e-05 Kg

Lower Calorific Value, LCV = 44 MJ/K

`eta_(comb) = (1241.16)/((3*10^-5)*(44*10^6))`

`eta_(comb) = 0.9402`

Combustion efficiency, `eta_(comb) = 94.02`

4. use the engine performance calculator, to determine the power and torque for this engine.

• Here we can take the value of gross work from the engine performance calculator to calculate the power.

From the above table, the work done is 468.646 Nm.

The time duration of the simulation is = 240.199 deg

The Power formula given is, `P=(2*pi*N*T)/(60)`

Here, `P = (WORK)/(TIME)`

Here we have time is in Degrees, so we need to convert it into Seconds.

Revolutions per minute = 3000

Revolutions per second = 3000/60 = 50

Degrees per second = `50*360 = 18000`

Time of combustion = `(240.199)/(18000)=0.0133 sec`

Since Power, P = Work/Time = `(468.646)/(0.0133) = 35236.54 W`

So, now we have the power. We need to convert this power to Torque.

Using the Power formula we can find the Torque.

`P=(2*pi*N*T)/(60)`

`T=(60*P)/(2*pi*N)`

`T=(60*35236.54)/(2*pi*3000)`

`T = 112.16`N*m

5. What is the significance of ca10, ca50, and ca90?

• The Significance of the CA10, CA50, and CA90 is, these are the crank angles at particular stages of the combustion process.
• CA10 represents the crank angle at which 10 % of combustion is occurred and respectively.
• CA10 is considered as the starting point of the combustion process and CA90 is considered as ending point of the combustion process.
• Where CA50 is the midpoint of the combustion process, which tells us that at this point the maximum heat release rate recorded from the combustion.
• Combustion phasing angles of 10%, 50%, and 90% of heat release (CA10, CA50, and CA90) are
  determined by integrating the AHRR (Apparent Heat Release Rate). Crank angles between CA10 and CA90 (CA10–90) are calculated to analyze the combustion duration.

Conclusion:

• Performed the No-Hydro case and come to a conclusion that, geometry has no type of errors, and perfectly moving valves at the respective time intervals.
• Further moved with Full-Hydrodynamic case and performed. The results like pressure, temperature, and heat release rate, etc are discussed.
• The animations of Adaptive mesh refinement, temperature, velocity, pressure, and mass fractions of IC8H18 before combustion and mass fraction of CO2 after combustion is attached and discussed the phenomena.
• Answered the five questions elaborately which has been the part of the challenge.