Wind-Tunnel Wall Interference Reduction by Streamwise Porosity Distribution

Self correcting wind tunnels

“…. (6) and, unless the values 8 2 cr (x, 8) are found to be satisfactorily small, one must re-adjust the wall configuration. The sensors then record new values <r m " (x, 8) and r m " (x, 8), and so forth until 8<x (x, 8) is as small as required.…”

“…Unfortunately, the art does not seem to have stabilised, for the demands upon the tunnel designer are often conflicting. He finds, for example, that a tunnel-wall configuration to prevent blockage is not the same as to eliminate wave reflection' 6 '. There have been proposals for refinements such as non-uniform distribution of porosities and/or plenum pressure < 5 ' 6 -7 ' 8 '.…”

Streamwise porosity distribution optimization for minimising wall interference in a transonic wind tunnel

“…An optimized and non-uniform porosity distribution along the test section centerline instead of an uniform value can be used in order to maximize the reduction of the wall interference over the widest possible Mach number range 1,2,3,4 .…”