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Develop Efficient/Leak Proof M1 Abrams Plenum Seal


OBJECTIVE: Develop innovative M1 Abrams plenum seal approaches which are efficient/leak proof to current production seals. The leak proof plenum seal (LPPS) will connect the turbine inlet foreign object debris (FOD) screen to the air cleaner plenum box (ACPB) inlet during power pack installations preventing dust and water intrusion during vehicle operation. DESCRIPTION: LPPS is an innovative solution to seal and align M1 Abrams components ((power- pack assembly and air cleaner plenum box (ACPB)) which must be joined together through the LPPS in an inaccessible area. This alignment and sealing procedure occurs each time the power-pack is installed in vehicle hull. The latest production seal design (baseline metrics) requires one end of seal be clamped to front of turbine engine"s FOD screen. The power package with production seal attached is then jockeyed and lowered into position until the other seal end presses against front of ACPB and power pack is locked in place. It is intended that to make sure the seal is seated and pressed against front edge of ACPB with no air gaps that a physical inspection be made through a small access cover in vehicle hull (baseline metrics). A physical inspection is not an easy task and may require power package removal and re-installation to assure proper seal alignment and re-positioning of seal to ACPB. The present production seal (one clamp design) and an earlier production seal (two clamp design) is not considered leak proof and water/dust can and have penetrated into engine compressor section causing engine damage and short engine life. Plenum seal installations in the field/camp posts are more tortuous and hazardous to perform than compared to control setting such as Army Depot"s/test sites creating increased risks and barriers which continues to lead to degraded turbine life and a need for design upgraded/refinement to production seals or a new innovative LPPS design. To assure that a new design plenum seal is properly installed metrics based on performance attributes shall include: (1) alternative new seal configurations ( such as tongue and groove and inflatable tube designs to leak proof mating components) which prevent seal leak paths between the ACPB to turbine inlet FOD screen, (2) this includes verification that seal design will not allow water intrusion into the engine during vehicle deep water fording tests, and (3) a new seal configuration and installation method that does not require underneath vehicle physical inspection to verify proper seal alignment. This research effort might incorporate, (1) new materials with a new technique which is more fool proof for engaging the mating components into M1 hull during power pack installation and (2) alternatives as to which mating component the seal is attached to first prior to M1 Abrams power pack installation. The specific technical challenges faced in the development of the LPPS are (1), understanding how the two current production seals maintain contact integrity between the air cleaner plenum box and turbine FOD screen during power pack installation and (2) current recommendation to physically crawl underneath vehicle and inspect through access cover for verification of seal alignment with no air gap between mating parts. The LPPS will provide a longer turbine engine life and more efficient fuel utilization by maintaining compressor blades integrity over longer sustained periods. Not knowing if the current production plenum bell mouth seal is properly installed creates a technical challenge and higher risk for engine compressor blade dust erosion and/or water intrusion into compressor section to occur. Knowledge of current seal design and limitations may aid in upgraded/refinements to current design or provide design savvy for developing new LPPS. Any new design alternative rubber type material must be required to meet or exceed current turbine engine bell mouth plenum seal"s specification requirements. PHASE I: Leak Proof Plenum Seal (LPPS) concepts will be explored, designed and developed based on the quantitative metrics sited in performance attributes defined in Description. The LPPS design concepts can be an upgraded/refinement of the two current production seals or a new seal design which develops a tongue and groove approach (or equivalent) compared to present design of seal pressing against outer metal lip of air cleaner housing. Included will be a trade off analysis of how LPPS will achieve leak proof conformance without intended need for seal verification by inspection through M1 Abrams hull following power pack installation. The trade-off analysis will also factor in and include the environments/operating conditions which the field/camp post installs the plenum seal in comparison to environments/operating conditions at Army Depot"s/test sites. Consultations with engine, vehicle developer, user organizations, M1 Abrams and M1 Abrams overhaul facilities (Anniston/Lima) may be useful in establishing design parameters for trade-off analysis predictions. The goal of Phase I is to determine the scientific and technical merit and feasibility of a new innovative LPPS or upgraded/refinement of current seals. The LPPS development will lead to a commercialization potential demonstrating a vast improvement in M1 Abrams engine life and reduced operational and overhaul cost across the M1 Abrams vehicle fleet. Breadboard designs and/or reduced scale LPPS concepts and/or upgraded/refinements of existing seals will be proposed and demonstrated. Computational fluid dynamics (CFD) and finite element analysis (FEA) techniques will be established (if needed) to support modeling and simulation efforts. PHASE II: Early in Phase II, the LPPS breadboard concepts studied and analyzed through trade-off evaluation in Phase I will be finalized (if needed) and the best one or two concept approach with government approval will be down selected. Prior to down selection, the quantitative metrics regarding the performance attributes will be verified and/or modified where applicable. Prototype hardware based on Phase I efforts will be built and the operation of the prototype will be demonstrated and verified. The demonstration will include operating conditions which may differ from field/camp post scenario to those operating conditions at Army Depot"s and test sites. Design modifications to prototype original design will be incorporated and re-test will be conducted based on previous lab results and modeling up dates from the CFD and FEA work efforts, if used in Phase I. Continued lab tests including turbine engine power pack installations typically seen in field/camp posts and Army Depot"s/test sites will be verified to realize a hardening of the design approach which will demonstrate no dust or water intrusion through the LPPS or design upgrade/refinements to existing production seals. Consultations and sub-contractor efforts with engine, vehicle developer, user organizations, and overhaul facilities may assist in establishing power pack installation trials and LPPS verification or refinement designs of current seal success. The LPPS design will be a well-defined plenum seal which meets all of Description Section, metrics, research goals and technical challenges outlined or restructured as deem necessary. The LPPS will be made commercially viable and provide a dual-use through possible new material development which may keep dust and water from penetrating in other critical areas of vehicle systems or in other critical enclosures requiring leak proof sealing. PHASE III: The primary or end-state vision of the LPPS is the current M1 Abrams turbine engine which requires a leak proof connection during power pack installation between the engine"s foreign object debris (FOD) screen and face of air cleaner plenum box permanently mounted in vehicle hull. The U.S. Army, U.S. Marines and some foreign countries which operate in dusty environments could use a new designed LPPS which is efficient/leak proof and provides a Cost Benefit Analysis (CBA) case to show increase engine life and reduced operational costs. It is envisioned that if Phase II effort is successful that M1 Abrams will fund a Phase II Enhancement to build LPPS prototypes to verify their success in field tests. This will also include support work on design, logistics and Technical Manual upgrades. LPPS application in commercial market would be most likely in developing new rubber type materials which retain sealing capability in temperature variations from 60 F to +350 F. REFERENCES: (1) SAE International, Aerospace Material Specification (AMS7258) titled: Rings, Sealing Butadiene-Acrylonitrile (NBR) Rubber Fuel Resistant, Low Shrinkage, 65-75, Approved for Public Release, Reaffirmed April 2001. (2) SAE Aerospace Material Specification (AMS3383), titled: Polytetrafluoroethylene (PTFE)-Fluorosilicone (FVMQ) Rubber High Temperature Fuel and Oil Resistance, 75-85, document declared"Stabilized"Sept 2011, Available from SAE International. (3) Ordnance Drawing 19207-122287063, Seal Assy, Engine Plenum (newer design). (4) Ordnance Drawing 19207-12388137, Seal Assy, Engine Plenum--Material Spec. (5) Ordnance Drawing 19207-12273764, Seal Assembly (old design)--Material Spec. (6) Ordnance Drawing 19207-12273122-3 Band Clamp. (7) Portions of Technical Manual showing procedure for installing and removing power package from M1 Abrams Hull and procedure for connecting to air cleaner housing.
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