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Vibrissae (whiskers) of Phoca Vitulina (Harbor Seal) and Mirounga Angustirostris (Elephant Seal) possess undulations along their length. Harbor Seal Vibrissae have been shown to reduce vortex induced vibrations and reduce drag compared to appropriately scaled cylinders and ellipses. Samples of Harbor Seal vibrissae, Elephant Seal vibrissae and California Sea Lion vibrissae were collected from the Marine Mammal Center in California. CT scanning, microscopy and 3D scanning techniques were utilized to characterize the whiskers. Leading edge parameters from the whiskers were used to create a 3D profile based on a modern power turbine blade. The NASA SW-2 cascade wind tunnel facility was used to perform hotwire surveys and pitot surveys in the wake of the ‘Seal Blades’ to provide validation of Computational Fluid Dynamics simulations. Computational Fluid Dynamics simulations were used to study the effect of incidence angles from −37 to +10 degrees on the aerodynamic performance of the Seal blade. The tests and simulations were conducted at a Reynolds number of 100,000 based on inlet conditions and blade axial chord. The Seal blades showed consistent performance improvements over the baseline configuration. It was determined that a fuel burn reduction of approximately 5% could be achieved for a fixed wing aircraft.

A Large Civil Tiltrotor (LCTR) conceptual design was developed as part of the NASA Heavy Lift Rotorcraft Systems Investigation in order to establish a consistent basis for evaluating the benefits of advanced technology for large tiltrotors. The concept has since evolved into the second-generation LCTR2, designed to carry 90 passengers for 1,000 nautical miles at 300 knots, with vertical takeoff and landing capability. This paper explores gas turbine component performance and cycle parameters to quantify performance gains possible for additional improvements in component and material performance beyond those identified in previous LCTR2 propulsion studies and to identify additional research areas. The vehicle-level characteristics from this advanced technology generation 2 propulsion architecture will help set performance levels as additional propulsion and power systems are conceived to meet ever-increasing requirements for mobility and comfort, while reducing energy use, cost, noise and emissions. The Large Civil Tiltrotor vehicle and mission will be discussed as a starting point for this effort. A few, relevant engine and component technology studies, including previous LCTR2 engine study results will be summarized to help orient the reader on gas turbine engine architecture, performance and limitations. Study assumptions and methodology used to explore engine design and performance, as well as assess vehicle sizing and mission performance will then be discussed. Individual performance for present and advanced engines, as well as engine performance effects on overall vehicle size and mission fuel usage, will be given. All results will be summarized to facilitate understanding the importance and interaction of various component and system performance on overall vehicle characteristics. PR= pressure ratio PSFC = power specific fuel consumption, lbm/hour/SHP r0 = engine rated output, for NO x emissions standard, kN SHP = shaft horsepower SLS = sea level static T3= compression system exit temperature, °F T4 = combustor exit temperature, °F TOGW = takeoff gross weight Vbr = aircraft best-range speed VSPT = variable-speed power turbine °C = degrees Celsius °F = degrees Fahrenheit

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SUMMARYParametric engine performance calculations were carried out for an alrturbo ramjet (ATR). A LOX-LH2 rocket-powered turbine powered the compressor. The engine was "flown" over a typical flight path up to Mach 5 to show the effect of engine off-design operation.The compressor design efficiency, compressor pressure ratio, rocketturbine efficiency, rocket-turbine Inlet temperature, and rocket-chamber pressure were varied to show their effect on engine net thrust and specific Impulse at Mach 5 cruise.Estimates of engine weights as a function of the ratio of compressor air to rocket propellant flow and rocket chamber pressure are also Included.In general, the Mach 5 results Indicate that Increasing the amount of rocket gas produced Increased thrust but decreased the specific Impulse. The engine performance was fairly sensitive to rocket-chamber pressure, especially at higher compressor pressure ratios. At higher compressor pressure ratios, the engine thrust was sensitive to turbine Inlet temperature. At all compressor pressure ratios, the engine performance was not sensitive to compressor or turbine efficiency.