Abstract: A blade outer air seal assembly includes a plurality of seal segments circumferentially disposed about an array of blades rotatable about an axis, each of the plurality of seal segments having a radially inner surface facing a tip of each blade of the array of blades, the radially inner surface having an arrangement of trenches formed therein, and a radially outer surface opposite the radially inner surface. The arrangement of trenches is disposed between 30% and 80% of a chord of a blade of the array of blades as taken at the respective tip, and the arrangement of trenches is aperiodic in the axial direction.

Abstract: A cascade wind tunnel T-bar turbulence generating grid for creating a turbulence intensity in an air flow having an air flow volume for testing at least two turbine blades having a turbine blade dimension and a pitchwise location, the turbulence generating grid comprising a plurality of cross bars having a front surface and a cross bar gap, a plurality of vertical bars having a vertical bar front surface and a cross bar gap and at least two support bars assembled to form a plurality of air flow. The support bar at an angle ? to the air flow and about parallel to the turbine blades. The cross bars mounted to the support bar such that the cross bar front surface is perpendicular to the air flow. The vertical bars are mounted to the support bar such that the vertical bar front surface is perpendicular to the air flow and wherein the vertical bar gap and a horizontal gap provide the turbulence intensity about constant across the pitchwise location.