Power & Mobility DEVELOPMENT OF AN EFFICIENT, LEAK PROOF PLENUM SEAL FOR THE M1 ABRAMS ENGINE INLET Steve Tarnowski Steve Pennala Great Lakes Sound and Vibration Inc. 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Background Mobility • The plenum seal couples the M1 turbine engine inlet to the air intake plenum. • Several factors lead to foreign object debris (FOD) and water ingestion past the seal, leading to premature wear on turbine compressor blades and other components. – Dimensional variations among vehicles causes extreme misalignment between the plenum box and the turbine inlet – Ability of the seal to properly engage the plenum box outlet ring – Difficulty in accessing the seal to ensure proper installation before engine startup • GLSV worked with TARDEC GVPM to develop a new plenum seal 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Goals Mobility • Significantly improve sealing performance and reliability • Simplify seal installation, both on the engine and on the plenum box during powerpack installation • Provide a means to easily verify proper installation • No changes to the plenum box or turbine inlet/FOD screen Current plenum seal • Maintain or reduce current seal procurement installed on turbine FOD screen assembly costs 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Challenges Mobility • Need to account for large dimensional variation between the turbine inlet and the plenum box outlet • Blind installation of the seal during power pack installation – Seal installation trajectory leading to the final seated position • Extreme operating environment – Ambient temps from -60°F to 300°F – Chemicals such as turbine fuel, engine oil, hydraulic oil, etc. – Shock and vibration 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Design Requirements Mobility • Sealing envelope – GLSV measured twelve M1 engine compartments and powerpacks at the Anniston Army Depot (ANAD) to quantify the variance in alignment between the turbine inlet and plenum outlet – Measurements were taken using high precision laser-scanning equipment. – Measured data was compared to hull drawings to completely define the sealing envelope • Flexural strength, durability and environmental requirements were taken from the current production seal drawing CAD assembly based on vehicle scan data 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Seal Design Process Mobility • GLSV developed the seal design specification based on the expected range of misalignment. • The misalignment specification was based on vehicle measurements, combined with a tolerance stackup based on vehicle hull drawings. • GLSV created 3D CAD models of the power pack, plenum box, and hull interface points. These assembly models were used to simulate the motion trajectory during powerpack installation into the vehicle. 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Seal Design Process Mobility • In addition to the final installed misalignment, the simulated installation trajectory path was also considered in the seal design process: 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Seal Design Process Mobility • Seal material selection considered the best compromise of material properties to meet the environmental requirements. • Several seal design concepts were developed, considering material and processing requirements and manufacturing considerations. • Preliminary finite element analysis (FEA) was performed to evaluate sealing/leakage performance for the expected range of misalignment. • One seal concept was eventually down selected for further design optimization. 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Seal Design Process Mobility • FE Model of Seal Assembly 2D axisymmetric FEA was performed to rapidly optimize the seal and zero in on favorable seal geometry. • Detailed 3D FEA was performed to include the seal, FOD screen, plenum ring, and a partial model of plenum box. • Simulated the seal stretched over the plenum ring, with applied radial clamp force. • Combined radial and axial offsets were then applied. • FEA predicted seal stress/strain and sealing contact pressures. 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Prototype Development Mobility • Molding process was developed to validate manufacturability and provide prototype seals for lab testing and vehicle fit checks: – Single cavity transfer mold – Several molding trials were conducted to produce good parts – Tooling and transfer molding method were developed with production intent – Minor modifications/improvements will yield consistent, high quality parts in production • Prototypes molded with FVMQ and HNBR rubber – FVMQ offers resistance to extreme temperatures and weather – HNBR offers superior abrasion resistance and flexural strength 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Lab Testing Mobility • Comparative lab tests of new FVMQ and HNBR prototypes and current production seal – High temp leakage performance – Installation and leakage performance through the range of misalignments – Combined environment leakage performance (high temp and vibration) – Water submersion • Leak test fixture simulates the vehicle seal installation procedure, and can pull up to 100 iwg vacuum – Seal is translated through the installation trajectory and onto the plenum ring with force provided by hydraulic jacks – Fixture is completely sealed and vacuum pump pulls a vacuum on the simulated plenum box GLSV custom designed lab test fixture • Lab tests shows the GLSV seal would perform well on all twelve vehicles measured at Anniston. 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Vehicle Installation Trials Mobility • GLSV assisted ANAD mechanics with seal installation trials and fit checks with the prototype seals. • Four install/removal trials were performed on two vehicles. • The seal geometry and design features allowed for successful hands-free installation and removal. – Proper seating/engagement of the seal was verified by remote video cameras mounted inside the engine compartment. • GLSV received positive feedback from ANAD personnel – The prototype seal was easier to install on the FOD screen and engaged more smoothly with the plenum ring during power pack installation. – Also provides positive visual proof of proper seal engagement 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
Power & Conclusions Mobility • GLSV’s new plenum seal performed well in lab tests. • GLSV’s seal has improved vacuum leakage performance for a wider range of misalignment conditions. • GLSV seal performed well at elevated temperatures while undergoing vibration. • GLSV’s seal performed well in vehicle installation trials. • GLSV anticipates additional design improvements during the upcoming Phase-III SBIR effort to build on the previous work. • Our end goal is to have a production level TDP and production-intent tooling for our new plenum seal design. 8/21/2018 DISTRIBUTION STATEMENT A. Approved for public release; distribution unlimited.
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