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

Aim: Full-scale simulation of port fuel ignition (SI8)

Note: Please refer to the No- Hydro case for more information about the case setup .

In this project spray modelling and postprocessing, results are discussed.

Spray Modelling:

Injection Parameters

Fuel flow rate :7.5e-4 kg/s

Since for every 720 degree fuel is being injected with a rpm of 3000 -> Total mas per cycle results in 3e-5 kg=30 mg

Injection timing: -480 degree

Injection duration :191.2 degree

Fuel species : IC8H8

Fuel temperature : 330 K

Nozzle Parameters :

Nozzle diameter :250 `mu`m

Circular Injection Radius : 125 `mu`m

• 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

Source/Sink Modelling:

Spark Ignition parameters

Start of spark : -15 degrees

Duration of spark :10 degrees

spark location :[-0.003 0, 0.00915]

spark radius : 0.0005 m

Energy Source for spark

Source Shape:Sphere

Source Mode :Cyclic

Period:720 degrees

For source 0,

energy :0.02 J

start time :-15 degrees

End time : -14.5 degrees

For source 1,

energy :0.02 J

start time :-15 degrees

End time : -5 degrees

Combustion Modelling :

Fuel Species:IC8H8

Temporal Type:Cyclic

start time : -17 degrees

end time : 130 degrees

Combustion model: SAGE

Pressure plot :

Above plot depicts the pressure rise in the cylinder. At -15 before TDC spark is initiated and there after combustion proceeds and which leads to rise in the pressure .

Mean Temperature:

IC8H8 - Fuel mass

Heat wall transfer Model :

Wall Heat transfer model is essential because it also influences the overall efficiency of the engine. In this simulation, only the fluid domain is modelled and wall heat transfer is not considered. Hence it's not possible to compute the wall temperatures due to the absence of the physical properties of the wall. However, modelling wall heat transfer will result in increased simulation time. The idea is to focus on the objective of the research and accordingly investigations are made else it would be computational very expensive .

Volume (m^3)

Minimum Volume(trough) : 5.70298e-5

Max Volume(crest) : 0.000574218

Compression ratio : Max Volume/Minimum Volume=10.06

Heat Release rate :

Integrated Heat Release Rate

HRR

Emissions:

CO2

Nox

HC

Performance parameters:

Efficiencies can be computed using the rate of heat release

Int_HRR = 1241.14 J % Total heat release from above plot

Total Mass of fuel = 3e-5 kg = 30mg

LHV = 44 Mj/kg

Qin = Total mas of fuel * LHV

Combustion efficiency = Int_HRR/44e6 =1241.14 /Qin =94.03 %

Work :468.646 N-m

Power

Speed: 3000 rpm

RPS = Speed/60 = 50

Degrees per second = 50 * 360 =18000

Time of combustion :Combustion Duration/ Degrees per second=0.0133 sec

Power : Work /Time of combustion =468.646/0.0133=35236.54 Watt

We know

P= 2*pi*N*T/60

Re-arranging the above equation

T=60*P/2*pi*N= 2*35236.54/(2*3.142*3000)=112.16 N-m

Engine Performance Tool :

:

Significance of CA10, CA50 and CA90 :

CA10 CA50 and CA90 represent the crank angles at which the 10,50 and 90 % of the fuel is burned respectively. Most of the engine researcher focuses on the CA50, where 50 % of the fuel is burned. These basically start, mid and endpoint where combustion takes place.