4. dfSprayFoam

4.1. aachenBomb

Problem Description

This case simulates combustion inside a constant volume chamber based on an experimental setup at RWTH Aachen University. It can mimic, for example, the beginning of power stroke in a four-stroke diesel engine.

Operating Conditions in Brief

Chamber size (xyz)

0.02×0.1×0.02m^3

Initial Gas Temperature

800K

Initial Gas Pressure

5MPa

Initial Gas Composition (mass fraction)

23.4% O2, 76.6% N2

Fuel

n-heptane

Fuel Temperature at the Nozzle

320K

Fuel Injection Duration

1.25ms

Total Injection Mass

6mg

Configurations Different from OpenFOAM Case

Cantera is used instead of the built-in modules of OpenFOAM to solve the chemical reactions. Therefore, a chemical mechanism file in YAML format is required in the case directory, and the full name of the mechanism file (“xxx. yaml”) should be the entry after the keyword CanteraMechanismFile in constant/CanteraTorchProperties. Non-reacting simulation can be conducted by switching the entry after the keyword chemistry from on to off in constant/CanteraTorchProperties.

Results

../_images/aachenBomb.png

Visualization of temperature contours with large particle distribution

4.2. Sydney Spray Burner

Problem Description

A 2D-wedge case is used to simulate the dilute spray combustion processes inside a spray burner based on the experimental setup at Sydney University. It has been widely used for the study of droplet-chemistry-turbulence interaction.

Operating Conditions in Brief (Details can be found for Case EtF4 in [1] )

Chamber size (wedge, 4 degree)

0.104×0.500m^2

Initial Gas Temperature in Domain

293K

Initial Gas Temperature at Fuel Inlet

267K

Initial Gas Temperature at Pilot Inlet

2493K

Initial Gas Pressure

1Bar

Initial Gas Composition in Domain(mass fraction)

23.4% O2, 76.6% N2

Fuel

C2H5OH

Mass-flow Rate of Air Carrier

150g/min

Liquid Fuel Injection Rate

23.4g/min

Bulk Jet Velocity

24m/s

Bulk Burned Pilot Velocity

11.6m/s

Configurations Different from OpenFOAM Case

Cantera is used instead of the built-in modules of OpenFOAM to solve the chemical reactions. Therefore, a chemical mechanism file in YAML format is required in the case directory, and the full name of the mechanism file (“xxx. yaml”) should be the entry after the keyword CanteraMechanismFile in constant/CanteraTorchProperties. Non-reacting simulation can be conducted by switching the entry after the keyword chemistry from on to off in constant/CanteraTorchProperties.

Note

When running a wedge case with OpenFOAM, you may come across an error “Hitting a wedge patch should not be possible”. One solution is to comment out the lines with the “FatalErrorIn” call in src/lagrangian/basic/particle/particleTemplates.C. Details can be found in the thread [2].

Results

../_images/sydneySprayBurner.png

Reference

[1] Gounder, James Dakshina, Agisilaos Kourmatzis, and Assaad Rachid Masri. “Turbulent piloted dilute spray flames: Flow fields and droplet dynamics.” Combustion and flame 159.11 (2012): 3372-3397.

[2]https://www.cfd-online.com/Forums/openfoam/89003-3d-spray-vs-axisymmetric-spray-dieselfoam.html