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  • Other Sources  (17)
  • Acoustics  (11)
  • Fluid Mechanics and Thermodynamics  (3)
  • STRUCTURAL MECHANICS  (2)
  • Acoustics; Life Sciences (General)  (1)
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  • Other Sources  (17)
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  • 1
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    Design and fabrication of a radiative actively cooled honeycomb sandwich panel (1978)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The mass of a radiative actively cooled panel was compared to the mass of a bare actively cooled panel designed to the same conditions and constraints. The approach was to design and optimize a 0.61 x 6.1 m full scale panel which combines radiative and active cooling to control structural temperatures to levels compatible with use of lightweight materials and to fabricate a 0.61 x 1.22 m panel for performance testing. Results of the design and optimization of the full scale radiative actively cooled structural panel, including radiative concept selection, final configuration details, test panel description, and conclusions are summarized.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA. Langley Res. Center Recent Advan. in Structures for Hypersonic Flight, Pt. 1; p 449-492
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  • 2
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    Validation of the Predicted Circumferential and Radial Mode Sound Power Levels in the Inlet and Exhaust Ducts of a Fan Ingesting Distorted Inflow (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Fan inflow distortion tone noise has been studied computationally and experimentally. Data from two experiments in the NASA Glenn Advanced Noise Control Fan rig have been used to validate acoustic predictions. The inflow to the fan was distorted by cylindrical rods inserted radially into the inlet duct one rotor chord length upstream of the fan. The rods were arranged in both symmetric and asymmetric circumferential patterns. In-duct and farfield sound pressure level measurements were recorded. It was discovered that for positive circumferential modes, measured circumferential mode sound power levels in the exhaust duct were greater than those in the inlet duct and for negative circumferential modes, measured total circumferential mode sound power levels in the exhaust were less than those in the inlet. Predicted trends in overall sound power level were proven to be useful in identifying circumferentially asymmetric distortion patterns that reduce overall inlet distortion tone noise, as compared to symmetric arrangements of rods. Detailed comparisons between the measured and predicted radial mode sound power in the inlet and exhaust duct indicate limitations of the theory.
    Keywords: Acoustics
    Type: NASA/TM-2012-217253 , AIAA Paper-2011-2808 , E-18008 , 17th Aeroacoustics Conference; Jun 05, 2011 - Jun 08, 2011; Portland, OR; United States
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  • 3
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    Tone Noise Predictions for a Spacecraft Cabin Ventilation Fan Ingesting Distorted Inflow and the Challenges of Validation (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A fan tone noise prediction code has been developed at NASA Glenn Research Center that is capable of estimating duct mode sound power levels for a fan ingesting distorted inflow. This code was used to predict the circumferential and radial mode sound power levels in the inlet and exhaust duct of an axial spacecraft cabin ventilation fan. Noise predictions at fan design rotational speed were generated. Three fan inflow conditions were studied: an undistorted inflow, a circumferentially symmetric inflow distortion pattern (cylindrical rods inserted radially into the flowpath at 15deg, 135deg, and 255deg), and a circumferentially asymmetric inflow distortion pattern (rods located at 15deg, 52deg and 173deg). Noise predictions indicate that tones are produced for the distorted inflow cases that are not present when the fan operates with an undistorted inflow. Experimental data are needed to validate these acoustic predictions, as well as the aerodynamic performance predictions. Given the aerodynamic design of the spacecraft cabin ventilation fan, a mechanical and electrical conceptual design study was conducted. Design features of a fan suitable for obtaining detailed acoustic and aerodynamic measurements needed to validate predictions are discussed.
    Keywords: Acoustics
    Type: E-18071 , E-18071-1 , NOISE-CON 2011; Jul 25, 2011 - Jul 27, 2011; Portland, OR; United States
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  • 4
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    High heat flux actively cooled honeycomb sandwich structural panel for a hypersonic aircraft (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of a program to design and fabricate an unshielded actively cooled structural panel for a hypersonic aircraft are presented. The design is an all-aluminum honeycomb sandwich with embedded cooling passages soldered to the inside of the outer moldline skin. The overall finding is that an actively cooled structure appears feasible for application on a hypersonic aircraft, but the fabrication process is complex and some material and manufacturing technology developments are required. Results from the program are summarized and supporting details are presented.
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-CR-2959
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  • 5
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    Acoustic Measurements of an Uninstalled Spacecraft Cabin Ventilation Fan Prototype (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Sound pressure measurements were recorded for a prototype of a spacecraft cabin ventilation fan in a test in the NASA Glenn Acoustical Testing Laboratory. The axial fan is approximately 0.089 m (3.50 in.) in diameter and 0.223 m (9.00 in.) long and has nine rotor blades and eleven stator vanes. At design point of 12,000 rpm, the fan was predicted to produce a flow rate of 0.709 cu m/s (150 cfm) and a total pressure rise of 925 Pa (3.72 in. of water) at 12,000 rpm. While the fan was designed to be part of a ducted atmospheric revitalization system, no attempt was made to throttle the flow or simulate the installed configuration during this test. The fan was operated at six speeds from 6,000 to 13,500 rpm. A 13-microphone traversing array was used to collect sound pressure measurements along two horizontal planes parallel to the flow direction, two vertical planes upstream of the fan inlet and two vertical planes downstream of the fan exhaust. Measurements indicate that sound at blade passing frequency harmonics contribute significantly to the overall audible noise produced by the fan at free delivery conditions.
    Keywords: Acoustics
    Type: NASA/TM-2012-217692 , E-18375 , 12_158 , Inter-Noise 2012, The 41st International Congress and Exposition on Noise Control Engineering; Aug 19, 2012 - Aug 22, 2012; New York, NY; United States
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  • 6
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    Predicting the Inflow Distortion Tone Noise of the NASA Glenn Advanced Noise Control Fan with a Combined Quadrupole-Dipole Model (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A combined quadrupole-dipole model of fan inflow distortion tone noise has been extended to calculate tone sound power levels generated by obstructions arranged in circumferentially asymmetric locations upstream of a rotor. Trends in calculated sound power level agreed well with measurements from tests conducted in 2007 in the NASA Glenn Advanced Noise Control Fan. Calculated values of sound power levels radiated upstream were demonstrated to be sensitive to the accuracy of the modeled wakes from the cylindrical rods that were placed upstream of the fan to distort the inflow. Results indicate a continued need to obtain accurate aerodynamic predictions and measurements at the fan inlet plane as engineers work towards developing fan inflow distortion tone noise prediction tools.
    Keywords: Acoustics
    Type: E-18348-1 , 18th AIAA/CEAS Aeroacoustics Conference; Jun 04, 2012 - Jun 06, 2012; Colorado Springs, CO; United States
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  • 7
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    Numerical and Experimental Determination of the Geometric Far Field for Round Jets (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: To reduce ambiguity in the reporting of far field jet noise, three round jets operating at subsonic conditions have recently been studied at the NASA Glenn Research Center. The goal of the investigation was to determine the location of the geometric far field both numerically and experimentally. The combination of the WIND Reynolds-Averaged Navier-Stokes solver and the MGBK jet noise prediction code was used for the computations, and the experimental data was collected in the Aeroacoustic Propulsion Laboratory. While noise sources are distributed throughout the jet plume, at great distances from the nozzle the noise will appear to be emanating from a point source and the assumption of linear propagation is valid. Closer to the jet, nonlinear propagation may be a problem, along with the known geometric issues. By comparing sound spectra at different distances from the jet, both from computational methods that assume linear propagation, and from experiments, the contributions of geometry and nonlinearity can be separately ascertained and the required measurement distance for valid experiments can be established. It is found that while the shortest arc considered here (approx. 8D) was already in the geometric far field for the high frequency sound (St greater than 2.0), the low frequency noise due to its extended source distribution reached the geometric far field at or about 50D. It is also found that sound spectra at far downstream angles does not strictly scale on Strouhal number, an observation that current modeling does not capture.
    Keywords: Acoustics
    Type: E-13956 , Noise-Con 2003; Jun 23, 2003 - Jun 25, 2003; Cleveland, OH; United States
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  • 8
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    Mean Flow and Noise Prediction for a Separate Flow Jet With Chevron Mixers (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Experimental and numerical results are presented here for a separate flow nozzle employing chevrons arranged in an alternating pattern on the core nozzle. Comparisons of these results demonstrate that the combination of the WIND/MGBK suite of codes can predict the noise reduction trends measured between separate flow jets with and without chevrons on the core nozzle. Mean flow predictions were validated against Particle Image Velocimetry (PIV), pressure, and temperature data, and noise predictions were validated against acoustic measurements recorded in the NASA Glenn Aeroacoustic Propulsion Lab. Comparisons are also made to results from the CRAFT code. The work presented here is part of an on-going assessment of the WIND/MGBK suite for use in designing the next generation of quiet nozzles for turbofan engines.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2004-212906 , AIAA Paper 2004-0189 , E-14329 , 42nd Aerospace Sciences Meeting and Exhibit; Jan 05, 2004 - Jan 08, 2004; Reno, NV; United States
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  • 9
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    Flowfield Comparisons from Three Navier-Stokes Solvers for an Axisymmetric Separate Flow Jet (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: To meet new noise reduction goals, many concepts to enhance mixing in the exhaust jets of turbofan engines are being studied. Accurate steady state flowfield predictions from state-of-the-art computational fluid dynamics (CFD) solvers are needed as input to the latest noise prediction codes. The main intent of this paper was to ascertain that similar Navier-Stokes solvers run at different sites would yield comparable results for an axisymmetric two-stream nozzle case. Predictions from the WIND and the NPARC codes are compared to previously reported experimental data and results from the CRAFT Navier-Stokes solver. Similar k-epsilon turbulence models were employed in each solver, and identical computational grids were used. Agreement between experimental data and predictions from each code was generally good for mean values. All three codes underpredict the maximum value of turbulent kinetic energy. The predicted locations of the maximum turbulent kinetic energy were farther downstream than seen in the data. A grid study was conducted using the WIND code, and comments about convergence criteria and grid requirements for CFD solutions to be used as input for noise prediction computations are given. Additionally, noise predictions from the MGBK code, using the CFD results from the CRAFT code, NPARC, and WIND as input are compared to data.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA/TM-2002-211350 , AIAA Paper-2002-0672 , E-13167 , GRC-E-DAA-TN10116 , NAS 1.15:211350 , Aerospace Sciences Meeting and Exhibit; Jan 14, 2002 - Jan 17, 2002; Reno, NV; United States
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  • 10
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    NASA Clean-Sheet Fans: Design, Build Analyze, Test, and Report (2008)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A suggested topic in small fan research is presented. Presentation briefly describes the scope of an effort to design, build and test a ventilation class cooling fan. Comments are included for the following categories: information (available and needed), benefits and values, concerns, variations and alternatives, and interest.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: E-16730 , Quiet, Efficient Fans for Spaceflight Workshop; Apr 02, 2008 - Apr 04, 2008; Cleveland, OH; United States
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