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  • AERODYNAMICS  (8)
  • 1
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    A study of the rotor wake of a small-scale rotor model in forward flight using laser light sheet flow visualization with comparisons to analytical models (1992)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: An experimental investigation was conducted in the 14 by 22 ft subsonic tunnel at NASA Langley Research Center to quantify the rotor wake behind a scale model helicopter rotor in forward flight (mu = 0.15 and 0.23) at one thrust level (C sub T = 0.0064). The rotor system used in the present test consisted of a four-bladed, fully articulated hub and utilized blades of rectangular planform with a NACA-0012 airfoil section. A laser light sheet, seeded with propylene glycol smoke, was used to visualize the flow in planes parallel and perpendicular to the freestream flow. Quantitative measurements of vortex location, vertical skew angle, and vortex particle void radius were obtained for vortices in the flow; convective velocities were obtained for blade tip vortices. Comparisons were made between the experimental results and the wake geometry generated by computational predictions. The results of these comparisons show that the interaction between wake vortex structures is an important consideration for correctly predicting the wake geometry.
    Keywords: AERODYNAMICS
    Type: In: AHS, Annual Forum, 48th, Washington, June 3-5, 1992, Proceedings. Vol. 1 (A93-35901 14-01); p. 697-719.
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Inflow measurements made with a laser velocimeter on a helicopter model in forward flight. Volume 4: Tapered planform blades at an advance ratio of 0.15 (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into the scale model helicopter rotor in forward flight (mu sub infinity = 0.15). The measurements were made with a two-component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 146 separate locations in order to clearly define the inflow character. This data is presented herein without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in MS-DOS format.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100544 , AVSCOM-TM-88-B-007 , NAS 1.15:100544
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 3: Rectangular planform blades at an advance ratio of 0.30 (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (micron sub infinity = 0.30). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 180 separate locations in order to clearly define the inflow character. These data are presented without analysis.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100543 , NAS 1.15:100543 , AVSCOM-TM-88-B-006
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Inflow Measurements Made with a Laser Velocimeter on a Helicopter Model in Forward Flight. Volume 1: Rectangular Planform Blades at an Advance Ration of 0.15 (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley to measure the inflow into a scale model helicopter rotor in forward flight (microinf = 0.15). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 147 separate locations in order to clearly define the inflow character. This data is presented without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in Microsoft Corporation MS-DOS format.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100541 , AVSCOM-TM-88-B-004 , NAS 1.15:100541
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 5: Tapered planform blades at an advance ratio of 0.23 (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in the 14- by 22-Foot Subsonic tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (mu sub inf = 0.23). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the blade tips. A conditional sampling technique was employed to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 168 separate locations in order to clearly define the inflow character. This data is presented without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependenet values are included as part of this report on two 5.25 inch floppy disks in Microsoft Corporation MS-DOS format.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100545 , NAS 1.15:100545 , AVSCOM-TM-88-B-008-VOL-5
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 2: Rectangular planform blades at an advance ratio of 0.23 (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (mu sub infinity = 0.23). The measurements were made with a two-component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 180 separate locations in order to clearly define the inflow character. This data is presented without analysis.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100542 , NAS 1.15:100542 , AVSCOM-TM-88-B-005
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Helicopter rotor induced velocities theory and experiment (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An investigation has been performed to assess methods used for rotor inflow modeling. A key element of this assessment has been the recent acquisition of high quality experimental measurements of inflow velocities taken in the proximity of a lifting rotor in forward flight. Widely used rotor performance predictive methods are based on blade element strip theory coupled with an inflow model. The inflow prediction models assessed in this paper include the uniform inflow based on momentum, a skewed disk model, and two methods based on a vortex wake structure.
    Keywords: AERODYNAMICS
    Type: National Specialists'' Meeting on Aerodynamics and Aeroacoustics; Feb 25, 1987 - Feb 27, 1987; Arlington, TX; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Rotor inflow variability with advance ratio (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A comparative study is conducted for the results of inflow calculations based on several analytical wake methods and laser-velocimeter rotor inflow measurements near a rectangular four-bladed rotor system operating in forward flight. The induced-flow characteristics at all advance ratios were found to be unsymmetrical about the longitudinal centerline, with maximum downwash in the rear portion of the disk, and skewed toward the advancing blade-side. Comparisons among analytical methods show that the region of induced upflow over the rotor disk was effectively modeled only at an advance ratio value of 0.15.
    Keywords: AERODYNAMICS
    Type: Annual Forum of the AHS; Jun 16, 1988 - Jun 18, 1988; Washington, DC; United States
    Format: text
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