When some one mentions felt, I think of that stuff in 8x10 sheet sfrom the craft store.....
The felt yo describe is structurally sound, no sagging there even if wet
But I still have a the opinion that it is dense, and fairly non-porous and doesnt allow gas flow through/around the individual fibers,,, just reducig volume in the chamber and not interacting with the gas flow. Something more porous that allows gast owflow through would be much better IMO. then the material adds surfaces area for the gas to drag on and slow down.
Again, that may be my preconceptual prejudice, and definitely open to better ideas.
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