ACOUSTIC IMPEDANCE CONTROL FEATURE AND ACOUSTIC RESONATOR INSERT FOR AIRFOILS OF A GAS TURBINE ENGINE

An acoustic resonator (900, 1000) having a backing chamber (508, 512, 608, 612, 722, 822, 912, 1012) defining a respective volume V and a neck (506, 510, 606, 610, 720, 820, 910, 1010) arranged relative to the backing chamber and defining an opening (614, 718, 818, 916, 1016), wherein the neck has a length and a cross-sectional area. The acoustic resonator cell (502, 504, 602, 604, 714, 814, 906, 1006) satisfies the following relationships: (1) l/L = 0.2-0.8, where l is a length of the neck (506, 510, 606, 610, 720, 820, 910, 1010) and L is a depth of the backing chamber and (2) a/A = 0.02-0.20, where a is a cross-sectional area of the neck and A is a cross-sectional area of the backing chamber (508, 512, 608, 612, 722, 822, 912, 1012).