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Transonic Aerospike simulation for a rocket

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Old   October 23, 2018, 04:54
Default Transonic Aerospike simulation for a rocket
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Yannick
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Hi everyone, first post here!

I'm currently graduating for a master in aerospace engineering and for our final project, we are designing a transonic (maybe supersonic) rocket with a drag-reducing aerospike. The main goal is to compare the results with classical nose cones (Haack-karman for example).

I've been adivsed to use the Spalart-Allmaras physical model. The rest of the physical model is classical for compressible fluids (coupled flow, steady 2-dimensional).

Results are not promising for 3000 iterations. Residuals are way too high. Drag coefficient is constantly raising.

I've read somewhere that the kind of meshing can drastically change the results, do anyone as an idea how?

Here are some relevant screenshots:
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Old   October 23, 2018, 14:06
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That looks like no aerospike I've ever seen, is this purely a drag reduction device or does it also perform the flow expansion?

You might want to look at making a structured mesh with this using the directed mesher.

Are you initializing with the grid sequencer?
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Old   October 24, 2018, 12:22
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Hey I'm back. I've played with parameters and talked with several peoples. My solution finally converged, partly because I've enhanced my mesh on the surface of the rocket body. Now the y+ plot is constant around 100.
Residuals have converged below 0.001 (3000 iterations). Drag coefficient is stable. I think the results are finally solid!


Any comments on the results? improvement proposals?
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aerospike, residuals non convergence, spalart allmaras model, supersonic flow, transonic flow

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