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:
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:
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.