SBIR-STTR Award

The proposed research and development will focus on the feasibility of design and manufacturing of a flexible brush shroud for compressor blade tip seals to enhance its aerodynamic efficiency and stall margin. Unlike current abradable seals, brush shroud bristles are expected to elastically deflect when impacted by blade tips and minimize permanent tip gap enlargement and tip damage, thereby reducing maintenance costs. Preliminary tests at Wright Laboratories with conventional brush seals have already demonstrated encouraging results. The proposed program will explore two innovative shroud designs, one based on flexible bristle strips and another on a tufted ring, both to generate a continuous sealing surface which is believed to be necessary to enhance sealing. The conventional brush seal design did not provide a continuous sealing surface. The proposed design will also be lighter and cheaper than the current seal design as a result of the elimination of redundant front and back plates. The proposed methods are also amenable to a high degree of automation, and Phase I will outline further development areas for a fully automated process. Advanced Components & Materials, Inc. has assembled a strong team to develop and commercialize this flexible shroud technology.

The proposed Phase II program will optimize the design and manufacturing process of a compliant brush shroud casing. Recent tests at Wright Laboratories with staged brush seals have demonstrated significantly increased blade to shroud rub tolerance of a compliant casing. Phase I of the program is expected to demonstrate the feasibility of two innovative brush shroud designs with lower cost and weight than staged brush seals. This will be achieved by eliminating the front and back plates of conventional brush seals and incorporating the compliant casing only in the forward section of the blade chord where the effect of reduced tip clearance is most significant. Phase II will down select an optimum brush shroud design and manufacturing process by further testing at Wright Laboratories and establish a target life-cycle cost based on current repair costs. Phase II will also include fabrication of a compliant shroud casing for technology demonstration in an advanced military engine program at GE Aircraft Engines.

Keywords:
Compliant Shroud Casing, Improved Efficiency, Cost Reduction, Reduced Maintenance