Investigating port resonance absorbers and port geometries

The experiments done so far are very useful. But have you thought about analyzing the rectangular bass reflex openings? Like L-acoustics KS28, KS21, EAW SBX118, SBX218, etc?
ks28-port-1_1110204.jpg ks28-airflow_1117984.jpg ks18_1168555.jpg
 
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In the past, i have made an experiment with a speaker in which I built 2 bass reflex openings, each tuned to the same frequency, 37hz. By covering one of them and positioning the speaker always with the opening down, I listened and measured in each individual case, but I found no obvious advantages for the port with nfr=0.5. It is true that both are generously sized, the straight port has 750 cm2 and the rounded one has a minimum section of 600 cm2, the box having an interior of approximately 200l, the speaker being 18tbx100.
box.jpg imp.jpg port drept.jpg port nfr 0.5.jpg
 
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stv

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but I found no obvious advantages for the port with nfr=0.5
for very big port surfaces the advantage is probably not noticeable / measurable. the air verlocity and displacement is very low anyways and in addition the curvature of walls does not hugehly reduce the port cross section surface.

the main advantages with flared ports would mostly be noticeable with smaller 2-way midwoofers.

thanks for sharing your experience!
 
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