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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

A method for calculating strut and splitter plate noise in exit ducts: Theory and verification

Portions of a four-year analytical and experimental investigation relative to noise radiation from engine internal components in turbulent flow are summarized. Spectra measured for such airfoils over a range of chord, thickness ratio, flow velocity, and turbulence level were compared with predictions made by an available rigorous thin-airfoil analytical method. This analysis included the effects of flow compressibility and source noncompactness. Generally good agreement was obtained. This noise calculation method for isolated airfoils in turbulent flow was combined with a method for calculating transmission of sound through a subsonic exit duct and with an empirical far-field directivity shape. These three elements were checked separately and were individually shown to give close agreement with data. This combination provides a method for predicting engine internally generated aft-radiated noise from radial struts and stators, and annular splitter rings. Calculated sound power spectra, directivity, and acoustic pressure spectra were compared with the best available data. These data were for noise caused by a fan exit duct annular splitter ring, larger-chord stator blades, and turbine exit struts.

Fink, M. R.↗
NASA NTRS1980

Fabricating wedge-shaped beam splitters

Fast economical fabrication produces wedge-shaped beam splitter with 0.3 micrometer edge, compared to conventional methods that have yielded 2 micrometer edges. Typical beam splitter made by new process is prism-shaped with right-triangle cross-section.

Fleetwood, C. M., Jr.↗
NASA NTRS1979

Noise from struts and splitters in turbofan exit ducts

An analytical method for calculating noise radiation from isolated airfoils in turbulent flow was combined with a method for calculating transmission of sound through a subsonic exit duct and with an empirical far field directivity shape. This combination provides a method for predicting engine internally generated noise from radial struts and stators and annular splitter rings. Calculated sound power spectra, directivity, and acoustic pressure spectra are compared with data. These data were for noise caused by a fan exit duct splitter ring, large-chord stator blades, and turbine exit struts. However, the lack of turbulence intensity and scale length measurements for these flow ducts prevented an absolute validation of the prediction method.

Fink, M. R.↗
NASA NTRS1991

Beam Splitter For Welding-Torch Vision System

Compact welding torch equipped with along-the-torch vision system includes cubic beam splitter to direct preview light on weldment and to reflect light coming from welding scene for imaging. Beam splitter integral with torch; requires no external mounting brackets. Rugged and withstands vibrations and wide range of temperatures. Commercially available, reasonably priced, comes in variety of sizes and optical qualities with antireflection and interference-filter coatings on desired faces. Can provide 50 percent transmission and 50 percent reflection of incident light to exhibit minimal ghosting of image.

Gilbert, Jeffrey L.↗
NASA NTRS1992

Computation of the flow field in a centrifugal impeller with splitter blades

To support the design effort of the Space Transportation Main Engine (STME) Fuel Pump Stage, viscous flow calculations were performed in a centrifugal impeller with splitter blades. These calculations were carried out with a Navier-Stokes solver (MINT), which employs a linearized block-implicit Alternating Direction Implicit (ADI) procedure to iteratively solve a finite difference form of the system of conservation equations of mass, momentum, and energy in body-fitted coordinates. A computational grid was generated algebraically for the 'channel' between two main blades of the impeller and extended both upstream of the impeller inlet and downstream of the impeller exit so that the appropriate boundary conditions could be applied. The results of the calculations show that although the overall level of flow distortion near the impeller exit is not very large, there is a noticeable difference between the flow patterns in the two 'passages' (one passage between the pressure side of the splitter blade and the suction side of the next full blade).

Dejong, Frederik J.↗
NASA NTRS2015

Shape Memory Alloy Rock Splitters (SMARS) - A Non-Explosive Method for Fracturing Planetary Rocklike Materials and Minerals

A static rock splitter device based on high-force, high-temperature shape memory alloys (HTSMAs) was developed for space related applications requiring controlled geologic excavation in planetary bodies such as the Moon, Mars, and near-Earth asteroids. The device, hereafter referred to as the shape memory alloy rock splitter (SMARS), consisted of active (expanding) elements made of Ni50.3Ti29.7Hf20 (at.%) that generate extremely large forces in response to thermal input. The preshaping (training) of these elements was accomplished using isothermal, isobaric and cyclic training methods, which resulted in active components capable of generating stresses in excess of 1.5 GPa. The corresponding strains (or displacements) were also evaluated and were found to be 2 to 3 percent, essential to rock fracturing and/or splitting when placed in a borehole. SMARS performance was evaluated using a test bed consisting of a temperature controller, custom heaters and heater holders, and an enclosure for rock placement and breakage. The SMARS system was evaluated using various rock types including igneous rocks (e.g., basalt, quartz, granite) and sedimentary rocks (e.g., sandstone, limestone).

NiTiHf↗
NASA NTRS1971

Variable ratio beam splitter for laser applications

Beam splitter employing birefringent optics provides either widely different or precisely equal beam ratios, it can be used with laser light source systems for interferometry of lossy media, holography, scattering measurements, and precise beam ratio applications.

Brown, R. M.↗
NASA NTRS1972

Unsupported thin film beam splitter

Multilayer beam splitter system yielding nearly equal broadband infrared reflectance and transmittance in the 5 to 50 micron spectral region has been developed which will significantly reduce size and cost of light path compensating devices in infrared spectral instruments.

Bastien, R. C.↗
NASA NTRS1972

Oscillation of laser-beam intensity as observed with beam splitters

Characteristics of nearly perfectly flat beam splitter for observing laser pulse shapes are discussed. Disadvantages of conventional instruments for observing properties of laser beams are described. Effects of high frequency noise on accuracy of measurement are reported.

Kuehn, D. M.↗