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

 Title: Simulation of Full Hydro 4-Stroke PFI(Port fuel injection)

Objective: 1. To understand the entire case setup 

                  2. Simulation of PFI Engine in paraview

                  3. To calculate the engine performance parameters value 

 Introduction 

PFI Engine                                       

Historically, the most widely produced internal combustion engines were of the Port Fuel Injected (PFI) design, where the fuel is sprayed into the intake ports to mix with incoming air. In fact, many new vehicles are still manufactured with this engine design. The fuel injectors in PFI configurations are typically mounted in the intake manifold and the air/fuel mixture is pulled into the cylinder head as the intake valve opens.

Theory: As in previous chaleenge PFI engine is run with No hydro simulation & checked the movement of piston, valve etc. This challenge is realted with the  full hydro simulation of Port fuel injection engine. for that there is collect the data related with the engine , spark nozzle postion  etc. this data is fill up in to case setup & run for crank angle degree & post procress the result. in this challenge its very important to find out the Compression ratio, combustion efficiency etc.

Given geometery 

      

Boundry name created

                         

         

Case setup:

1 Application type -Crank based IC Engine

            Cylinder bore=0.0856m 

            Crank raduis=0.09

            Connecting rod length=0.18

            Crank speed=3000 rpm

2.Materials

         Gas simulation>import them.dat file

         Reaction mechanism> import mech.dat

         Turn on >Parcel simulation

Parcel simulation

As we are simulating gasoline fuel in to the PFI  engine. so, we need to select the relative parcel that will behave like gasoline fuel . so, there is consider IC8H18 (Iso-octane) liquid. here its very important to observe the various properties value & it should be nearly match with gasoline fuel

      

3. Simulation parameter

        Solver> Transient

         Temporal type> Crank based simulation

         Simulation mode> Full-hydrodynamic

Simulation time parameter

            Start time= -520 deg

            End time= 120 deg

            Intial time step=1e-7

            Intial time step=5e-7 , maximum time step= 2.5e-5

 

           

4.Boundry condition

Outflow

 comnustion product is given CO2, N2, H20

    

Inflow

at inflow air quantity is flow

    

Liner

   Boundry type> Wall            Surface movement> fixed

   motion type>stationary      Temp > 450k           Turbulent tke> zero normal gradient

Cylinder head

    Boundry type> Wall            Surface movement> fixed

   motion type>stationary        Temp > 450k           Turbulent tke> zero normal gradient

Exhaust port

    Boundry type> Wall            Surface movement> fixed

    motion type>stationary        Temp > 500k           Turbulent tke> zero normal gradient

Exhaust valve top

     Boundry type> Wall            Surface movement>moving    profile>exhaust lift.in

     wall motion type>Translating       Temp > 525k                 Turbulent tke> zero normal gradient

Exhaust valve angle

     Boundry type> Wall            Surface movement>moving     profile>exhaust lift.in

     wall motion type>Translating       Temp > 525k           Turbulent tke> zero normal gradient

Exhaust valve bottom

     Boundry type> Wall            Surface movement>moving    profile>exhaust lift.in

     wall motion type>Translating       Temp > 525k           Turbulent tke> zero normal gradient

Intake valve bottom

     Boundry type> Wall            Surface movement>moving     profile>intake lift.in

     wall motion type>Translating       Temp > 480k           Turbulent tke> zero normal gradient

Intake valve angle

     Boundry type> Wall            Surface movement>moving     profile>intake lift.in

     wall motion type>Translating       Temp > 480k           Turbulent tke> zero normal gradient

Intake valve top

     Boundry type> Wall            Surface movement>moving     profile>intake lift.in

     wall motion type>Translating       Temp > 480k           Turbulent tke> zero normal gradient

Spark terminal

     Boundry type> Wall            Surface movement>fixed

     wall motion type>Stationary      Temp > 600k           Turbulent tke> zero normal gradient

Spark plug

     Boundry type> Wall            Surface movement>fixed

     wall motion type>Stationary      Temp > 550k           Turbulent tke> zero normal gradient

Intake port-

     Boundry type> Wall            Surface movement>fixed

     wall motion type>Stationary      Temp > 425k           Turbulent tke> zero normal gradient

Intake port-B

     Boundry type> Wall            Surface movement>fixed

     wall motion type>Stationary      Temp > 425k           Turbulent tke> zero normal gradient

Intial condition & events

Region & Intialization

Cylinder

after combsution process species formed in three name CO2, H20, N2

                          

Intake system

at intake only air send it

                         

Intake system 2

Fuel is injection through nozzel , so that there is use of parcel IC8H18 (Iso-octane)

                         

Exhaust system

                       

Event is created

for flow the fuel from intake system to cylinder region event is created, so that disconnected triangle is created & it will be broken so, that flow of fuel is start, its same for exhaust port after combustion process is over. For intake system2 & intake system event is open

Physical modeling

Spray modeling

 By click on Physical modeling we can choose the spray modeling. spray modeling is nothing but the injecting the fuel in to intake port.

        

1. General: Parcel distribution evenly throughout the cone. this option is select for petrol fuel because of distribution of fuel evenly. so, that combustion process will be complete

2. Turbulent dispersion: O route model. this consider for maintain the turbulent effect. for petrol fuel typicall this option uses

3. Evporation model: its uses for conversion of fuel in to small diameters molecule

    Evporation Source: 0-Source specified species. for conversion of liquid fuel in to the IC8H18 fuel

Collision breakup model

  Colision model: NTC collision

 

Wall interaction

its used for when fuel is hit to the wall film it will splash in to the combustion chamber by use of O route model

       

Injector

By use of injector fuel (Iso-octane) is injected in to the intake port

Models

Kelvin-helmhotz & rayliegh taylor model for spray the fuel in the form of cone shape. constant are provided for breakup the fuel.

Select the discharge coefficient is 0.8

     

Time temp & size

total injected mass is 3e-5 kg for perticulat time for once in 720 degree

Injection type is cyclic

Nozzle location

nozzle location & orientation  is cartesian 

Nozzle specification

Nozzle diameter=0.00025m   Injection radius=.000125m

Location of Nozzel is set

coordinate & spray orientation location has been set

Combustion modeling

Consider the SAGE combustion model

General of combustion

Combustion is cyclic for every 720 degree

Start time of combustion -482 degree

end time of combustion 131.3 degree(at exhaust valve opening)

      

Souce & sink modeling

Basically there is provided two spark plug which is heat source & there is provided energy equation. value for heat source is provided 20 MJ. sink is fuel having temp. is increases by energy equation. 

spark is start at -15degree

end time -14.5degree

Source 1

      

Source 2

Heat source location

                      

Grid control

base grid size=.004m

Fixed embedding

 Embeeding 1: Cylinder > Permanent                    

Fixed embedding= (base grid size)/2^n

  base grid size uses =0.004m

   n=2= scale

  fixed embedding= 0.004/2^2

                              = 0.001 m

 

 Embeeding 2: Boundry > Intke valve angle                    

Fixed embedding= (base grid size)/2^n

  base grid size uses =0.004m

   n=3= scale

 embedd layer=2

  fixed embedding= 0.004/2^3

                              = 0.0005 m

 

 Embeeding 3: Boundry > Exhaust valve angle                    

Fixed embedding= (base grid size)/2^n

  base grid size uses =0.004m

   n=2= scale

 embedd layer=2

  fixed embedding= 0.004/2^2

                              = 0.001 m

 

 Embeeding 6: INJECTOR > cyclic                   

Fixed embedding= (base grid size)/2^n

  base grid size uses =0.004m

   n=4= scale

start time=-485 degree, end time =-265 period= 720 degree

  fixed embedding= 0.004/2^4

                              = 0.00025 m

Adaptive mesh refinment

Adaptive mesh refinment based upon the velocity & temprature

Sub grid criteria for velocity is based on 1m/s  velocity .Velocity timing control is permanent

Sub grid criteria for Temprature is based on 2.5k.Temp timing control is Cyclic for 720 degree. Temp AMR start at -17 deg & end at 131 deg

Embedd level is 3 for both refinment

Result

1.Pressure plot 

its shows accurate pressure plot as compression pressure is increases & high at combustion start

Mean temp

High temp occurs at the start of combustion process

Heat rate

High heat rate occurs at the start of combustion process

Emission

Higher HC emission at the start of combustion process

Compression ratio of engine

compression ratio can calculate by volume graph

Compression ration = Maximum volume/ minimum volume

                                = 5.7 *e-4/5.7 *e-5

                                =1e-9 *1e10

                                =10:1

Combustion efficiency

Combustion efficeincy tell us how much amount of heat is developed & its utlization for burning of fuel. combustion efficency tell us how perfectly combustion process take place. higher combustion efficiency higher power production & lesser emission

Combustion efficiency = Total heat released by combustion/ total heat content available in fuel

Total heat content of fuel= amount of fuel*calorific value

                                   =3e-5 kg/cycle * 44*e6 J/kg

                                    =1320J

COMBUSTION EFFICENCY= 1241/1320 

                                     =94%

Power & Torque of Engine

 

From the engine performance calculator we got the workdone 468.646 N-m for the process

Rpm =3000   RPS= 50     DPS(Degree per second)=3000 *6=18000

Time per degree=60/ 360*RPM 

                      =5.55*e-5

Time per 720 degree=0.04

 time per 240.199degree=0.01334sec per cycle

POWER= 468.646/0.01344

          =35.13KW

Power =2piNT/60

            =111.8N-m

What is Ca10, Ca50, Ca90

Ca10 = 10% of the combustion take place. so, 10% combustion will take place at intial stages of combustion process 

Ca50 = 50% of the combustion take place. so, 50% combustion process will take place at half of combustion process.

Ca50 = 90% of the combustion take place. so, 90% combustion process will take place at the end of combustion process.

What is need of wall heat transfer model

heat transfer is important factor that affect on the performance, emission of engine. in CFD simulation we generally uses near wall measurment under CFD simulation. but there is some heat losses occurs its due to temprature gradient across wall, therfore here to reduce heat losses combustion heat transfer model. in the CFD simulation for capture heat transfer assumption are made , but its correct. so, by the wall heat transfer model we accurately predict the heat transfer.

Animation of Full hydro Simulation

         

Overall conclusion

1.Calculate the  compression ratio by volume

2.Calculate the  Combustion efficiency intergrate heat rate

3. Calculation of POER & TORQUE

4. importace of wall heat transfer model