Session: 6.1.1 - Student Competition

Paper Number: 108776

108776 - An Innovative Seal Concept for Aircraft Engines 

Today, both the government and private aircraft companies strive for faster, lighter, and less expensive aircraft to stay competitive in both the national and international arena. This is only possible with continuous innovation and sustainability efforts for aircraft systems such as fans, compressors, combustors, and turbines, as well as the sub-systems including engine seals. Advanced engine seals show significant promise for improving the engine pressure ratio and cycle temperatures, which result in lower engine weight, stronger thrust, and higher fuel efficiency. With the advancement of sealing technologies, engines can run more efficiently due to the ability to operate at a higher pressure ratio. With an increase in pressure ratio of approximately 50 percent, larger engines would run efficiently at a 50-60 to 1 pressure ratio. In general, as the pressure ratio increases, the engine's overall size to produce the same output decreases. When aircraft engines operate at a higher-pressure ratio, turbine inlet and discharge temperatures also increase. The significant increase in pressure ratios and operational temperatures has the potential to save both operational costs and the overall weight of the system. In addition to saving on the overall weight of the system, there is a strong correlation between the reduction of leakage within the engine and an increase in overall thrust. The development of an innovative low leakage seal is also incredibly cost-effective, costing approximately 4 to 5 times less than redesigning the turbine and compressor stages of aircraft engines. In this study, we propose an innovative multistage seal concept that leverages the well-known ElastoHydroDynamic (EHD) lubrication theory. EHD seal has a simple sleeve-like structure sitting on the rotor with an initial clearance of h₀. When the engine starts and the pressure builds up, the pressures, and thus pressure forces, at the top and bottom of the seal force the sleeve to bend downward, creating a physically possible minimum clearance closer to the root of the sleeve. This throttling effect becomes stronger as the engine pressure increases. In the present study, to prove the concept, a computer-based simulation modeling approach was embraced. Due to the highly non-linear nature of the complex the Fluid-Solid-Interactions (FSI), a fully coupled Finite Element Analysis (FEA)-Computational Fluid Dynamics (CFD) based modeling is adopted for the design of the seal system. With the recent improvements in the commercially available software, COMSOL Multiphysics software was employed to carry out the fully-coupled FSI simulations. The modeling approach was presented thoroughly, and the results were discussed. The leakage was found to be less than 0.010 kg/s at 2.75 MPa. As for future studies, the considerations for the test rig were also presented.

Presenting Author: Md. Wasif Hasan Georgia Southern University

Presenting Author Biography: Md. Wasif Hasan is a Graduate Assistant in the Department of Mechanical Engineering at Georgia Southern University. Mr. Hasan's research is on innovative sealing systems for turbomachinery. Prior to joining Georgia Southern, Mr. Hasan had worked as a Research and Development Engineer at Walton Hi-Tech Industries PLC in Bangladesh, where he performed theoretical, numerical, and experimental studies to improve the efficiencies of compressors, including computer simulations on Crankcase, Crankshaft bearing, and Outer Shell.