Multidimensional Simulation of a Spark Ignited Port Fuel Injected (SI-PFI) Engine using CONVERGE CFD (Part 2/2)

PART 1 - SI-PFI Engine - Surface prep, Boundary flagging & No-Hydro Case setup

******************************************************************************************

I. INTRODUCTION

After Post-processing the No-Hydro setup & verifying the case parameters runs as specified, the part 2 of this project advances with full hydrodynamic simulation performing Combustion modelling of the SI-PFI engine cylinder using SAGE - a detailed chemical kinetics solver. This study is done to evaluate the emissions such as Nox & Soot produced during combustion and understand the performance parameters of the engine such as power, efficiency, maximum temperature attained in the combustion chamber. The project begins with theoretical explanation of Spray modelling - spray breakup process, proceeding to combustion modeling & details of SAGE in Converge software. Then the importance of regions & events required for IC engine modeling & the importance of ring triangles in surface preparation for valve movements which was not included in part 1. Necessacity of wall heat transfer models for prediction of wall temperature of IC engine blocks & Significance of CA10, CA50 & CA90. 

II. OBJECTIVES

1. Set up Spray modeling - Injector & Nozzles along with Source modeling.

2. Full Hydrodynamic Case-setup - Combustion modeling, Grid Control parameters & miscellaneous.

3. Stoichiometric Combustion, Species mass fraction & fuel mass injection calculation.

3. Evaluate emissions characteristics & Engine performance parameters. 

 

III. GEOMETRY 

[III.1] SI8 Multicylinder ENGINE

                             

This is a spark ignited 8 cylinder engine's fluid volume geometry. Performing analysis in all 8 cylinders is not feasible, thats why initial procedure is to perform combustion analysis on a single cylinder for a few cycles until convergence is observed & to monitor the engine parameters  as well as emissions and to make any necessary design changes required. 

 

[III.2] SI8-PFI SINGLE CYLINDER GEOMETRY (Completely prepared)

The only difference visually from part 1 is the nozzle & AMR setup explained in the Case-setup & Meshing later.  

                           

 

IV. MODELING THEORIES CONVERGE-CFD

[IV.1] SPRAY MODELING - Spray Breakup

Converge uses state of art models for spray processes involving liquid atomization, drop breakup, collision & coalescence, turbulent dispersion & drop evaporation. In terms of liquid sprays, Converge uses Lagrangian solver to model discrete particles and Eulerian solver to model the continuous fluid domain. Lagrangian specification of the flow field is a way of looking at fluid motion where the observer follows an individual fluid parcel as it moves through space and time. Plotting the position of an individual parcel through time gives the pathline of the parcel. The Eulerian specification of the flow field is a way of looking at fluid motion that focuses on specific locations in the space through which the fluid flows as time passes. The eulerian cell center is fixed while the lagrangian parcels moves. Heat, momentum & mass transfer occur between the discrete and continous phases via source terms in transport equations.

                     

Parcels are introduced into the domain at the injector, which presents a group of identical drops with same radius. velocity and temperature. Parcel is the basic unit converge solves instead of drop. Parcel undergoes several physical processes like, Pirmary breakup, secondary breakup, drop drag, collision & coalescence, turbulent dispersion & evaporation. 

                                       

[IV.1.1] Evaporation Model

The spray evaporation that takes place need to be considered and for that converge uses a certain standard pre-created models such as Frossling, Chiang or with boiling. In this project Frossling model is used and its not needed to provide particular equations of the model as Converge takes care of it. Converge asks for evaporation source to simulate multi-component vaporization. The source used in this project is "Source all base parcel species" which denotes multi-component liquid species evaporate into base species.   

As the evaporation source is specified, the maximum radius of ODE droplet heating needs to be specified as well, its basically a temperature discretization parameter which will control if drop temperature is uniform or radially varying. If drop radius exceeds max value then converge assumes a radially varying temperature or else Uniform temperature distrubution. 

[IV.1.2] Spray Penetration & Distribution

Converge writes the liquid and vapor penetration lengths at each output interval, it calculates vapor penetration length for each nozzle. For each cell that meets the critera that fuel vapor mass fraction exceeds user specified value or cell size does not exceed user specified bin size, converge calculates the distance from the center of nozzle to the center of the cell. 

The parcel distribution is done in two ways where the parcels are either distributed evenly throughout the cone or clustered near the center of the cone. Depending on requirement either distribution can be selected, for this project even distribution is selected.

                                

             

[IV.1.3] Collision/Coalescence & Drop Drag

If in a spray simulation parcels collide with parcels only in the same cell, it can lead to grid sensitivity, which is why converge has an adaptive collision mesh to reduce grid sensitivity. Once collision mesh is checked, the parcels can collide across grid cells, requiring no additional meshing or any other setup. In this project it is done using a standard NTC collision model & dynamic drop drag model with default TAB model constants to determine drop distortion. Dynamic drop drag calculates the drag coefficient to account for variation in drop shape as shown in spray breakup. In the pic below it is observable that parcels with collision mesh look more reasonable & natural. Other drop options are spherical drop drag & No drop drag. 

                     

[IV.1.4] Injector & Nozzle

Once the spray breakup, & Parcel modeling is done, Injector and nozzles need to be specified, their locations, model, radius and such. One injector can have multiple nozzles and for this project there are 4 nozzles in one injector, This is done as per the engine manufacturer's requirement based on the amount of fuels and speed at which the fuel has to be sprayed inside the chamber. Thei injector has a profile rate_shape.in where its rate vs crank is determined is is shown below.

                                                   

The fuel is specified for this injector as IC8H18 with mass fraction 1 as only 1 fuel is being sprayed in this cylinder. There are two spray type, solid cone spray and hollow cone spray. Kelvin-Helmholtz & reyleigh taylor models are used for solid cone sprays. Discharge coefficient recommendation for gasoline PFI - correlation for CV - 0.8 is set.

Nozzles are added next into the injector where nozzle parameters are determined such as diameter, injection radius and spray cone angle as well as co-ordinates of nozzle. 

                        

 

[IV.2] COMBUSTION MODELING in CONVERGE

Combustion facilitates the energy transfer in the engine. Converge contains detailed chemistry solver and simplified combustion models. 

                     

[IV.2.1] SAGE detailed chemical kinetics solver (used in this simulation.) 

SAGE solver is the most predictive and accurate way to model combustion, it can accurately model ignition and laminar flame propogation. It uses local conditions to calculate reaction rates based on principles of chemical kinetics. Also determines kinetically limited phenomena such as engine knock and emissions. It requires a CHEMKIN-formatted input files to solve the reaction rates & ODE'S. The ODE solver used is called as CVODE solver. SAGE couples with transport solver via source terms in the species transport equations. 

A chemical reaction mechanism is a set of elementary reactions that describe an overall chemical reaction. The combustion of different fuels can be modeled by changing the mechanism (e.g., there are mechanisms for isooctane, gasoline, n-heptane, natural gas, etc.). SAGE calculates the reaction rates for each elementary reaction while the CFD solver solves the transport equations. Given an accurate mechanism, SAGE (in addition to AMR) can be used for modeling many combustion regimes (ignition, premixed, mixing- controlled). You can use SAGE to model either constant-volume or constant-pressure combustion.

In each time-step, the chemistry solver calculates the new species mass fractions immediately prior to solving transport equations. The change in species mass fractions is treated as source. 

                 

Omega is the relaxation source term, which takes the values. Detailed mathematical formulation can be found Converge 3.0 manual.

[IV.2.2] Accelerating SAGE 

As this is the most detailed solver, solving it in every cell can be expensive, time consuming. Converge has accelerating options which require increasing minimum cell temperature and min HC species mole fraction to reduce the number of cells in which combustion calculations are performed. Using start time and end time to limit sage to specific time interval & can limit SAGE operation to specific region. Other options include, Setting resolve only if temperature changes by specified value ~ no greater than 2 K. & using analytical jacobian to pass an analytically calculated jacobian to solver. SAGE cal also reduce time by using multizone modeling where it groups cells into bins (zones) for which appropriate options are provided.

 

[V] CASE-SETUP 

Case-setup of FULL-HYDRO setup is explained, the spray modeling, source modeling, and additional parameters. The boundary flagging & regions can be referred from PART1. 

[V.1] Source modeling

 In this two energy sources are introduced just below the spark plug terminal just like the spark is produced. This energy is sourced through energy equation and that increases the temperature of the species. In species transport equation this temperature will be introduced in source term which will result in new products, heat release and new species to be formed.

Activating Source/sink modeling from physical models, 2 sources are created with same settings except for start and end time. 

                         

                        

                    

[V.2] Spray modeling 

                           

                          

As per the theory explained above, the spray modeling set up is shown below 

               

Nozzle Locations - 

• Nozzle 0
  • center 0.0823357 0.00100001 0.07019
  • Align Vector -0.732501 0.210489 -0.647408
• Nozzle 1
  • center 0.0823357 -0.00099999 0.07019
  • Align Vector -0.732501 -0.210489 -0.647408
• Nozzle 2
  • center 0.0823357 -0.0004 0.07019
  • Align Vector -0.5 -0.2 -0.647408
• Nozzle 3
  • center 0.0823357 0.0003 0.07019
  • Align Vector -0.5 0.2 -0.647408

Spray rate graph

This graph is obtained from tools - spray rate preview, where we can see the graph of the rate shape according to other modeling parameters we put in wrt Crank angle provided in rate shape.

                 

 

[V.3] Combustion Modeling setup

                

 

[V.4] Fuel & Parcel Simulation 

The fuel used in this simulation is IC8H18 - Iso-octane, it is chosen because it has physical properties very close to gasoline fuel. It is used in relatively large proportions to increase the knockresistance of the fuel.

                            

Parcel Simulation specifies the fuel being used, It can be set up from predefined liquids in parcel simulation option in converge. Once the chosen fuel is selected converge incorporates all its properties as seen below, to utilize it in the chemical reactions and combustion simulation.

                     

 

[V.5] Full Hydro Case Setup 

The entire case setup is tabulated with the flow of settings done in CONVERGE STUDIO for full hydrodynamic case. Detailed Boundary condition, regions & events settings and other parameters are laid out in the table. In Full Hydrodynamic mode converge solves all Navier stokes equations, transport equations, turbulent equations along with chemical kinetics & input files to solve the combustion, solving all the models for spray, parcels etc. 

Note - In boundary conditions "TKE B.C - Zero Normal Gradient & Turbulent dissipation - wall model" for all unless specified otherwise.

                      

                     

                    

 

[V.5.1] Regions, Events & Importance of Ring Triangles

 In the case setup above the details on the B.C of the regions are shown. The regions are created for this unique reason that Specific B.C can be applied in that particular region & club multiple boundaries together along with Species concentration. Another primary importance of creating regions is to Couple it with EVENTS, to execute them in motion profiles of valves like as simple as creating a no-flow region which is either cyclic or sequential or simply an open port. Converge provides specifc valve events which read the valve profile and create disconnect triangles in the regions to pause the flow when valve is closed.

                         

Events Creation for Valve - Disconnect Triangles

                        

The region interfaces shown above are joined by disconnect triangles as shown in the images. Converge recognizes Valves from the boundary condition & valve profiles and automates this in version 3.0. If these are not created then there will be open sections during combustion and a large error in the simulation which will come from improper fuel input & incorrect backflows & temperature variations etc. hence without these combustion in IC engine is not possible for accurate results in CONVERGE CFD.                        

                       

 

Importance of Ring Triangles: 

These are the Ring triangles which are required to be created in the geometry in Converge above all 4 valves and it is important to flag it to either the exhaust port or intake port wherever the Valve is located. They connect the valve top to the Exhaust & intake ports in all cylinders according to their position. 

                      

Errors if RING triangles are not set as shown above. 

If the ring triangles are not set according to what is shown above, then the respective valve tops would appear so as shown in the picture. The No ring triangle valve is the one with the Ring joined with the valve instead of the intake port & the ring triangle joined with intake port is the one with ring triangle created, which is shown above as proper geometry. 

                     

This is how No-Ring Triangle cylinderical portion looks like, and during the valve movements as shown in the image below, Intake valves are moved down for the purpose of demonstrating the effect of improper ring triangles. When they are moves down, they pull the surface of the exhaust region in a conical way instead of straight down. 

                           

                                               Ring triangles joined with intake port                                                

                     

                                             Intake valve pulled down (demonstration)

                           

                                        Conical pull down of intake port geometry (INCORRECT)                                    

                      

                         Straight pull down of intake port geometry (CORRECT)

So without the ring triangle cylinder portion in place, when valve moves down the intake port regions flat geometry is pulled down in conical way, this disfigures the proper shape of the geometry and the conical shape can interact with fuel spray simulation & block air way when its fully down or just basically spoil the results.

                      

                                             intake geometry pulled down (INCORRECT)

 

[V.5.2]  Stoichiometric Combustion equation , Mass fraction of species & Fuel Calculations : 

The combustion is taken to be stoichiometric & the product formed is shown in the equation according to which we calculate mass fraction and feed in the case setup. Converge accepts mass fractions & a calculator is created in excel to calculate it. These sepcies are output and need to be added in outflow boundary aswell as exhaust, cylinder regions.  

                  `C_8H_18 + 12.5(O_2+3.76N_2) -> 8CO_2 + 9H_2O + (3.76*12.5)N_2`

Calculation steps

Moles x Molecular Weight = Mass 

`(Mass of Specie)/(Total Mass) = Mass Fraction`

                    

 

Fuel Calculation: 

It is required to feed in the injector, the total Fuel mass injected per cycle in KG. which is calculated using the excel sheet calculation shown below. 

From given data that fuel flow rate is 7.50e-04 kg/s and RPM 3000, it is possible to calculate absolute mass flowing per cycle in a period of 720 deg. 

The Rpm is converted into DPS - Degree/Second by RPS*360 which gives 18000 dps.

1/18000 = 5.55e-5 (Time per degree)

5.55e-5 x 720 = 0.04 (Time per 720 deg)

So we can calculate the total mass of fuel injected for 720 deg by 0.04 X 7.5E-04  = 3e-5 KG

                     

 

VI. GRID CONTROL CASE-SETUP

[VI.1] AMR - SGS CONCEPT 

Adaptive Mesh Refinement is a method of adapting & enhancing the accuracy of a solution within certain sensitive or turbulent regions of simulation, dynamically and during the time the solution is being calculated. When solutions are calculated numerically, they are often limited to pre-determined quantified grids as in the Cartesian plane which constitute the computational grid, or 'mesh'

In this Project, Subgrid scale AMR is used in the Temperature & Velocity variables of the Simulation . Converge calculates the second order of the variable subject to AMR embedding and while calculating if the difference is above the Sub-grid criterion, it will perform a refinement of the cells with embed level as provided. 

The formula used is : 

                      

                         

                                                         Velocity - SGS                                                                                                             

                    

                                                          Temp - SGS

The velocity Sgs is permanent whereas Temperature is cyclic with time period of the combustion period from the spark ignition to exaust valve opening period. Controlling the AMR is also very important because restricting it will reduce simulation time & capture only relevant parts & regions of combustion. Otherwise it will unnecessarily extend the simulation time alot. 

The Base grid size is 0.004 m

Velocity & Temperature sgs refinement - 0.004/2^3 = 5e-4 m mesh size

 

Clip: Mesh of Geometry (Cylinderical embedding & AMR)

                          

AMR in CYLINDER :

                            

[VI.2] FIXED EMBEDDING 

Fixed embedding follows same refinement formula except its not adaptive to solution progressing and is there for the mentioned period. 

For cylinderical & valve angle fixed embedding setup refer PART 1. 

Additional fixed embedding refinement added to Spark/ SOURCE added near the terminal & Injector - Nozzle spray area. 

1. Source - Fixed embedding 

Setup 

                             

                      

 

Two level of embedding is done, one for the initial spark & another a little bigger with smaller scale of refinement to capture the initial combustion phase. The timing is set initially before the spark ignites and remains till a little after it ends, this method of refinements are extremely useful to improve accuracy of the solutions. 

 

                      

                                                                          Embedding Source - converge studio setup

                     

                                                                                         Embedding - Source mesh generated

2. Injector - Fixed embedding 

Setup & contour

                            

                                                        Setup                                                                                                                   

                       

                                               injector - Fixed embedding

                         

                                                          Injector refinement mesh

Intake - Exhaust valve refinement 

The refinement near valve angle is shown along with valve movement, as well as the pressure contour which is higher on top of the valve on the intake side as the spray parcels push it open & on the exhaust valve since its closed hence due to low velocity there pressure increases 

                        

 

[VI.3] Total Cells 

This is the total meshing graph where we can observe how the mesh first decreased then increased. This is acting as per fixed embedding & AMR.

The maximum cell count achieved is 1.33629e+06

                   

 

The process of solving divided among multiple cores. The mesh data :

                   

 

[VI.4] TIMING MAP 

Timing map is like a pathway map which lays out all simulation timing details into something like a process chart which displays what procedure is taking place at what degree such as injector function, opening of intake port and displays the type of Grid control parameters are set on it. It gives a handy tool to verify everything in one place & see if some refinement or function is placed as desired or not.

                      

 

[VII] SOLUTION & POST PROCESSING

After complete modeling of case, the simulation is ran using CYGWIN command line terminal on a 16 core machine & it took one week to finish the entire simulation. Once its completed the data is converted to post process in PARAVIEW. 

 1. In-cylinder Pressure

The cylinder pressure contains different values at different strokes of the cylinder, the highest of which is observed in the Combustion/Expansion stroke. This stroke is where the spark plug ignites the air-fuel mixture, creating very high cylinder pressure which rises very quickly. This is where the engines power comes from, as it forces the piston down. As the piston goes down, cylinder volume increases which reduces the cylinder pressure right after it. The peak pressure obtained in this cylinder is 3.884 MPA. 

                    

 

2. Volume (inCylinder region) & Compression Ratio

The volume vs crank angle graph plotted in the cylinder region of the engine. It appears close to sine but its not purely a sine wave. It gives the distance of volume depending on crank angle. 

Compression ratio = Max Volume / Min Volume = `0.00057422/(5.7029*10^-5) = 10.0689`

                       

 

3. PV Plot 

The SI engine follows a typical otto cycle as can be observed from this pv plot, but the one from the simulation is an Actual cycle PV diagram & not theoretical. However the 4 stroke processes can be understood from the ideal cycle. The Pv diagrams were invented to improve the efficiency of engines originally. They're utilized to calculate the work done aswell which is usually given by 

W = `W = intP*dV` for a complete cycle. `

                      

 

 

It can be also calculated by calculating the area under the curve. Fortunately, Converge provides an engine performance calculator built in which can evaluate these terms. 

3.1 Engine Performance Calculator. 

                  

 

3.1.1. Work done (Gross) = 468.646 Nm.

3.1.2. Power = Work/Time

Where, Time is the combustion duration - `240.199°`

RPM - 3000 

RPS - 50 

DPS - 50*360 = 18000

Combustion duration in seconds = `240.199/18000 = 0.01334 s`

Power = Work/Time = 468.646/0.01334 = 35130 W.

3.1.3. Torque (T) = `(60P)/(2piN) = (60*35130)/(2*pi*3000) =`111.8 Nm`

 

4. Heat Release rate & Combustion Efficiency 

Heat release & Integrated heat release is plotted against crank angle. It gives the Amount of heat i.e total amount of energy released from combustion process.  From the total heat release in the combustion chamber, the combustion efficiency of the engine can be determined.

HR RATE

                    

Integrated HR RATE

                    

 

Combustion Efficiency -

It is defined as ratio of total heat energy released by burning of fuel to the total energy content of fuel mass in a cycle.

mass of fuel injected = 3e-5 Kg

Calorific value of fuel = 44e6 kJ/kg

Integrated Heat released = 1241 J

Combustion Efficiency = Integrated Heat released / Total heat energy content of fuel

                                = `(1241)/(m *CV) = 1241/(3e-5*44e6) = 0.9402`

Combustion Efficiency = 94.02%

 

5. Mean Temperature 

This is the mean temperature inside the cylinder region. The max value reached is 2483.55 K. This data can be used to check highest cylinder temperature & utilize in liner & engine design parameters & thermal analysis.

                       

5.1 Temperature Animation

This animation is post processed in Paraview displays the ignition time frame of the simulation. The spark occuring and temperature shooting up as the combustion begins is captured in a cutplane. 

                            

Temperature distribution & combustion. On the left side the spray discrete parcels are visible with their temperature & on the right gives the cut plane view. The spray parcels force their way into thevalve opening it in a turbulent way & inside the combustion chamber they vaporize & hence can be seen disappearing. Combustion can be observed along with valve movements, spark ignition zone.

                         

 

6. EMISSIONS

The major cause of emissions are non-stiochiometric combustion, dissociation of nitrogen, and impurities in the fuel and air. Even though we assumed a stiochiometric combustion for this project, it produced emissions because perfect combustion does not occur. The emissions of concern are unburnt hydrocarbons (HC), oxides of carbon (COx), oxides of nitrogen (NOx), SOx & Soot. The plots of emissions produced in this simulation is shown below. The emissions are produced in combustion region which is then pushed out from exhaust port. we're looking at the emissions produced in the combustion region. 

6.1 Hiroy Soot :

Soot is a mass of impure carbon particles resulting from incomplete combustion of hydrocarbons. The observation is as soon as the combustion process starts Soot started being accumulated in small quantity then peaks when the pressure is highest then dissolves slightly till it reaches approx 2.5e-8 kg. These are generated in the fuel rich zones within cylinder during combustion & come out as exhaust smoke.

                       

6.2 Nox, HC, CO,CO2 :

With a fuel rich mixture there is not enough oxygen to react wiith all the carbon resulting in high levels of HC & CO in emissions exhaust products. This is particularly true during starting when air fuel mixture is purposely made very rich. If air-fuel mixture is too lean poorer combustion again leads to HC emissions. Similar reasons lead to formation of CO & NOx. NOx is created mostly from nitrogen in air. NOx leads to photochemical smogs and there are stringent norms to reduce it. As observed from graph all the emissions are highest at the combustion stroke and slightly dips down the curve once peak is reached. The simulation was run for only 1 cycle so the data is not perfectly acceptable, it needs to be run for more cycles. This data is extremely important as it can be utilized to make necessary design changes & improve emissions. 

                 

 

6.3 Comparison of Emissions : 

                      

 

7. Spray parcels plot

Liquid spray drop vs crank angle plot gives the number of lagrangian parcels active in the cylinder region & intake port (injector) region. There are significantly large number of parcels that were injected almost double the size that reached maximum inside the cylinder region. Sometimes fuel vapourization occurs and some fuel gets trapped. we can observe that about 1 mg of fuel near the end of curve in 2nd plot of fuel. The parcel counts are extremely important because this is the fuel basically thats injected and to properly atomize it, combust it & overall simulation is highly dependent on it. 2nd plot of iso-octane gives the amount of fuel sprayed for the number of parcels injected.

1. Cylinder region. 

                                      

2. IC8H18 Icooctane (cylinder region)

                   

3. Intake port (Injector) region.

                  

 

Spray pacels contour

The inlet parcels in the velocity contour can be seen as they push on the intake valve their velocity reduces highly, as the valve opens some parcels are left behind after splashing back & the rest of the parcels move in and spread accross the cylinder and vaporize at later stage. 

  1.               

 

 2.                 

 

VIII. Necessity of wall Heat transfer model for prediction of wall temperature in CFD. 

Ic engines are extremely optimized, in such ways improving their performance is a costly task. Accuracy is important to have a good prediction of engine performance & modeling of heat transfer and wall temperature is a critical task of any engine thermodynamic model. Wall heat transfer modeling consists of solid addition to the fluid domain & it adds alot of parameters to calculate in addition to CFD's navier stokes equations. There is a difference in temperature of the wall and that of the fluid its in contact with. This difference is created by wall material's thermal resistance, heat transfer coefficient, thickness, overall heat flux. Proper data of such parameters is required specific to solid material being used & different grid control parameters such as near wall treatment, slip etc also play a great role in accurately predicting the wall temperature. Wall heat transfer models are required for accomplishing heat transfer from hot gases to engine parts, heat transfer inside each engine part and also heat transfer to coolant & lubricating oil etc. Important correlations need to be reviewed and simulation over relaxation parameters have to be utilized for such simulations to reduce the computational time aswell. Simulations include CHT like gas to wall, wall to wall and wall to liquid heat transfer models, and sometimes all 3 coupled speaking in terms of IC engine. Converge software provides an excellent feature called super-cycling which is extremely suitable in such simulations.

IX. Significance of CA10, CA50 & CA90.

The CA refers to Crank Angle follwed by its position in degree at 10%, 50% & 90%. These angles are captured to store the data such as heat release, combustion data and misc. The significance of it is that CA10 is used to determine start of ignition, CA50 determines end of premixed combustion and CA10-90 determines combustion duration. This data is used to compare the simulation data from experimental results or simulation data from previous results at specified percentages. Parameters like accuracy of pegging, encoder phasing, trapped mass estimate, Volume estimate, heat generation etc. Combustion phasing angles of heat release are determined by integrating the AHRR. 

 

X. CONCLUSION.

 1. Spark - ignition and diesel engines are major source of urban air pollution & it is extremely important to keep developing methods, refining engines, creating strategies to perform complete combustion in order to reduce pollution which is ever increasing. 

2. It is critical to perform the spray & combustion modeling accurately in converge as that would route the entire simulation correctly, otherwise the data obtained is not useful.

3. Grid control parameters like embedding & AMR are excellent in Converge & it should be utilized effectively as mesh determines the results accuracy & are critical to reduce over all simulation time for such extremely detailed cases. Without such Grid control measures the simulation would run for months & would be 2-3 times costlier.

4. The engine data obtained from this simulation can be taken out & analyzed in data visualizer programs automating plot post processing & calculation. One of the data visualizer & engine performance tool built by me can be checked out from here - Data Analysis of IC - Engine simulation using PYTHON 

5. The emissions data obtained can be used to understand if it meets the criteria against new emission norms such as BS VI & redesigning, refinement can be carried out.

6. Fuel mass in inlet, Trapped A-F ratio, Air inlet into the combustion chamber as per the cylinder & piston design can be obtained from which initial calculations for modeling the combustion can be done with more control & accuracy. Data from CA10, CA50, CA90 can be utilized to check simulation data & parameters against experimental or previous results. 

7. SAGE is an extremely powerful solver & clubbed with converge's advanced autonomous meshing & inbuilt models it can solve combustion very accurately & Converge have published several papers proving the same which can be referenced online.  

 

 keywords - CFD, COMBUSTION, IC-ENGINE-CFD, CONVERGE-CFD, PARAVIEW, SIMULATION, CAE

 

--------------------------------------------------------------------------------------------------- THE END -------------------------------------------------------------------------------------------------------