Week 7: Shock tube simulation project

GEOMETRY:

The geometry was imported to converge CFD and geometry clean up was done.

inside it extra traingle is deleted.

*Created as General flow

*Material- Air , gas simulation , global transport as default.

*Simulation parameters- Transient , full hydrodynamic , compressible.

*Simulation time parameter- 0sec to 0.003 sec.

*Solver parameter default.

*Turbulrnce kept as default hich is RNG k- Epsilon.

*Boundary flagging done as shown in below image.

*Base grid as 0.004m in as axis.

*BOUNDARY CONDITION

- Two regions is created HP(High pressure), LP(Low pressure).

- In HP region pressure of 600000pa as initalized , species as N2.

- In LP region static pressure of 101325pa used , species as O2.

EVENTS:

-Events created to develop the diaphragm movement.

- here at 0 sec from HP to LP diaphragm is closed.

- At 0.001sec diaphragm opened from HP to LP and remains opens.

Adaptive mesh refinement:

- Adaptive mesh refinement is created species N2 for 0.001 and 3 level of embed.

Processing:

- After setting up the case exported the input files in a folder to process the output.

-Open the cygwin and using mpi executable solving the input and 3D post data files is stored in output folder.

Post processing:

- Before going to post processing convert the output files.

- Post processing is done using the paraview for getting the 3D animations.

Pressure:

- Pressure inside the shock tube kept as high pressure of 600000pa and low pressure as 101325pa.

- When the diaphragm breaks due to the high pressure and high pressure gas flow through and tends to low pressure also reflected back and forth.

- Due to the pressure difference the shock occurs at high pressure after the diaphragm breaks.

- Thus the shock waves flows in suoersonic speed form an expansion fan with infinite number of mach waves.

- These reflects shock waves intiate the low pressure region to high pressure.

 pressure animation link:

https://youtu.be/UCWwGwidlHQ

Temperature:

- Due to the reflected shock waves the mean temperature increases or decreases according to the pressure difference.

- After the diaphragm brakes the temperature flutuates.

temperature animation link:

https://youtu.be/fSxjPOLM0oY

cell-count:

- Cell count is constant upto 0.001sec.

- Ater the diaphragm brakes cell count increases to 1190 cells then starting reflection of shock waves increases the cell count to 1450 cells in 0.0023sec.

CONCLUSION:

- The concept of shock tube is used in IC Engine to auto ignite and by modifying the design of shock tube we can achieve hypersonic flow.

- Using AMR shock wave is captured effectively.