Abradable fluid seal for aircraft gas turbines

An abradable fluid seal for use in the space between two relatively movable members, such as the circular space between the cylindrical path of the rotating blade tips in an aircraft gas turbine and the surrounding bore wall of the stationary casing of the turbine wherein the seal has a circular length, a radial thickness, and an axial width, comprising:

• A. a series of thin narrow elongate metal strips assembled in side-by-side or face-to-face relationship to form a flexible assembly composed of odd numbered alternate strips and even numbered interposed strips, said assembly having, in the direction of its thickness, an outer base portion and an inner seal portion, and, over a given length, one succession of undulations in its outer base portion and another succession of corresponding undulations in its inner seal portion,
• 1. the undulations in the base portion being three-sided semi-hexagonal figures, each having, between two slanted sides, a flattened crest which is bonded to the corresponding crest of a semi-hexagonal figure in an immediately adjacent strip so that said figures cooperate to form an integral honeycomb, the voids of which extend in the direction of the assembly's thickness dimension,
• 2. each undulation in the seal portion of each strip being axially aligned with a corresponding undulation in an adjacent strip and spaced therefrom so that immediately adjacent strips cooperate with each other to form therebetween a free undulating passageway, extending lengthwise of the assembly's seal portion,
• a. each alternate strip has its corresponding seal and base portion undulations point in the same direction, and
• b. each interposed strip has its corresponding seal and base portion undulations point in opposite directions.