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Munson, John

Publications and source records attributed to Munson, John.

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Foil Face Seal Testing

In the seal literature you can find many attempts by various researchers to adapt film riding seals to the gas turbine engine. None have been successful, potential distortion of the sealing faces is the primary reason. There is a film riding device that does accommodate distortion and is in service in aircraft applications, namely the foil bearing. More specifically a foil thrust bearing. These are not intended to be seals, and they do not accommodate large axial movement between shaft & static structure. By combining the 2 a unique type of face seal has been created. It functions like a normal face seal. The foil thrust bearing replaces the normal primary sealing surface. The compliance of the foil bearing allows the foils to track distortion of the mating seal ring. The foil seal has several perceived advantages over existing hydrodynamic designs, enumerated in the chart. Materials and design methodology needed for this application already exist. Also the load capacity requirements for the foil bearing are low since it only needs to support itself and overcome friction forces at the antirotation keys.

Munson, John↗
NASA NTRS2006

Advanced Seals and Secondary Airflow Systems for Allison AST

The author will present results obtained to date of a secondary flow study currently being conducted. The purpose of the study is to investigate and report all the ramifications of introducing advanced sealing technology into gas turbine engine secondary flow systems. In addition to detailed cost/benefit results we will also derive seal operational requirements which can be fed into a subsequent advanced seal development program. Using the current Allison AE3007 engine as a model/baseline we have examined 6 different advanced seal variations. We have settled on a design with 2 advanced seals which results n a savings of 2% in chargeable cooling. The introduction of these advanced seals has resulted in substantial changes to surrounding engine components which will be reported.

Munson, John↗
NASA NTRS1996

Innovative Sealing Technology for Next Generation Subsonic Engines

The next generation of subsonic engines can be expected to continue the historical trend towards increased thrust to weight (T/W) and decreased specific fuel consumption (SFC). Development programs currently underway throughout the gas turbine industry such as DOD's Integrated High Performance Turbine Engine Technology (IHPTET), and more recently NASA's Advanced Subsonic Transport (AST) programs, have altered these trends in both pace and magnitude. Advanced seals and sealing technologies have become a prominent part of these efforts due to the large potential performance gains which can be realized. Allison has recently completed a study for NASA the goal of which was to quantize the potential performance benefits which might accrue through the use of advanced seals in future subsonic gas turbine engines. For the study, two engines where analyzed, a small turboshaft and a larger turbofan engine to help assess the effect of engine size on the results. Engines were analyzed stage by stage with the most sensitive areas highlighted. Leakage characteristics for advanced seals were then substituted into secondary airflow models, and the leakage reductions documented. These leakage reductions were then converted to changes in performance, i.e. increased range, decreased takeoff gross weight, etc. and presented. It was found that the development and use of a realtively few advanced seals, less than 5, could for example reduce SFC by 10% or more.

Munson, John↗
NASA NTRS1994

Compressor discharge film riding face seals

Seals examined were the eight-pad Rayleigh step, the tapered spiral groove, and two hydrostatic seals. The spiral groove configuration is the preferred choice because of superior stiffness. Second choice is Rayleigh step because of combined higher operating film thickness and good stiffness at low clearance. Recess hydrostatic has reasonable performance, but stiffness falls off at low clearance. Also, pneumatic hammer characteristics must be investigated. Experience at high pressure ratios is limited. An advantage is that it would have good low speed performance.

Munson, John↗
NASA NTRS1991

Seal development activities at Allison Turbine Division

Brush seals are being evaluated for potential near and far term gas turbine engine applications. Development is in the form of rig component testing and engine testing. Allison has tested an engine with 20 individual brush seal positions. These seals were located throughout the engine. The emphasis of the current work is on obtaining long term performance data for brush seals. Very little of this data is available. Allison is presently developing film riding face seal technology to support future gas turbine engine applications. A face seal with an approximate 7 inch diameter was successfully tested to 1000 F, 100 psid, and 650 ft/sec. Seal leakage remained below 1 scfm throughout the duration of the test. A model for the compressible gas film was developed which separates the model for the compressible gas film was developed which separates the primary seal rings during operation. This model is based on the traditional Reynold's approach which is customarily applied to lubrication type problems. Because of the difficulty of experimentally verifying the program predictions, a commercial Navier-Stokes code was used in parallel. By comparing predictions for similar cases, it is expected that the limitations of the Reynold's model can be assessed as it applies to this particular seal.

Munson, John↗