scholarly journals Optical Measurement of Unducted Fan Blade Deflections

1990 ◽  
Vol 112 (4) ◽  
pp. 751-758 ◽  
Author(s):  
A. P. Kurkov
Keyword(s):  
High Speed ◽  
Optical Measurement ◽  
Leading Edge ◽  
Random Errors ◽  
Helium Neon Laser ◽  
Quantitative Analyses ◽  
Surface Reflectivity ◽  
Fan Blade ◽  
Helium Neon ◽  
Averaging Techniques

A nonintrusive optical method for measuring unducted fan (or propeller) blade deflections is described and evaluated. The measurement does not depend on blade surface reflectivity. Deflection of a point at the leading edge and a point at the trailing edge in a plane nearly perpendicular to the pitch axis is obtained with a single light beam generated by a low-power, helium-neon laser. Quantitative analyses are performed from taped signals on a digital computer. Averaging techniques are employed to reduce random errors. Measured static deflections from a series of high-speed wind tunnel tests of a counterrotating unducted fan model are compared with available predicted deflections, which also are used to evaluate systematic errors.

scholarly journals Optical Measurement of Unducted Fan Blade Deflections

1989 ◽  
Author(s):  
Anatole P. Kurkov
Keyword(s):  
High Speed ◽  
Optical Measurement ◽  
Leading Edge ◽  
Random Errors ◽  
Helium Neon Laser ◽  
Quantitative Analyses ◽  
Surface Reflectivity ◽  
Fan Blade ◽  
Helium Neon ◽  
Averaging Techniques

A nonintrusive optical method for measuring unducted fan (or propeller) blade deflections is described and evaluated. The measurement does not depend on blade surface reflectivity. Deflection of a point at the leading edge and a point at the trailing edge in a plane nearly perpendicular to the pitch axis is obtained with a single light beam generated by a low-power, helium-neon laser. Quantitative analyses are performed from taped signals on a digital computer. Averaging techniques are employed to reduce random errors. Measured static deflections from a series of high-speed wind tunnel tests of a counterrotating unducted fan model are compared with available predicted deflections, which are also used to evaluate systematic errors.

High-Speed Surface Roughness Measurement

1984 ◽  
Vol 106 (1) ◽  
pp. 34-39 ◽  
Author(s):  
D. G. Jansson ◽  
J. M. Rourke ◽  
A. C. Bell
Keyword(s):  
Surface Roughness ◽  
High Speed ◽  
Linear Array ◽  
Optical Measurement ◽  
Large Area ◽  
Incident Intensity ◽  
Neon Laser ◽  
Helium Neon Laser ◽  
Online Inspection ◽  
Helium Neon

A prototype apparatus is described that performs a real-time optical measurement of surface roughness in the 2 to 20 microinch AA range, typical of high-quality grinding, honing, and lapping. Ground metal manufactured parts, with surface roughness in the stated range, are illuminated with a 3.39 micron helium-neon laser. The scattering pattern from the surface is scanned across a linear array of lead selenide detectors. Analog and digital electronics control the scanning and measure the intensity incident on each detector. The electronics computes both reflected (specular) and total incident intensity. These two values are used to compute the surface roughness. The system completes a scan and the electronics computes surface roughness in 20 milliseconds. The fast measurement time allows a large area to be scanned. The results demonstrate the feasibility of using the apparatus for online inspection.

A Flow-System Multiangle Light-Scattering Instrument for Cell Characterization

1975 ◽  
Vol 21 (9) ◽  
pp. 1297-1304 ◽  
Author(s):  
G C Salzman ◽  
J M Crowell ◽  
C A Goad ◽  
K M Hansen ◽  
R D Hiebert ◽  
...  
Keyword(s):  
Laser Beam ◽  
High Speed ◽  
Clustering Algorithm ◽  
Flow System ◽  
Exfoliated Cells ◽  
Analysis Instrument ◽  
Helium Neon Laser ◽  
System Cell ◽  
Number Of Classes ◽  
Helium Neon

Abstract A flow-system cell-analysis instrument is described in which cells from a heterogeneous population are characterized by their light-scatter patterns alone. As the cells pass at high speed through a focused helium/neon laser beam, the scatter pattern from each cell is sampled simultaneously at up to 32 angles between 0° and 30° with respect to the laser beam axis, and the scatter pattern for each cell is transferred to a computer. A mathematical clustering algorithm is used to determine the number of classes into which the cells can be divided, and a linear separation algorithm is used to find the boundaries between the classes. Preliminary results on exfoliated cells from gynecological specimens are presented. This technique may be useful for automated prescreening of gynecological specimens.

The Effect of an Eroded Leading Edge on the Aerodynamic Performance of a Transonic Fan Blade Cascade

2014 ◽  
Author(s):  
A. Hergt ◽  
J. Klinner ◽  
W. Steinert ◽  
S. Grund ◽  
M. Beversdorff ◽  
...  
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Separation Bubble ◽  
Leading Edge ◽  
Suction Side ◽  
Chord Length ◽  
Blade Cascade ◽  
Shock Position ◽  
Fan Blade ◽  
Blunt Leading Edge

Especially at transonic flow conditions the leading edge shape influences the performance of a fan profile. At the same time the leading edge of a fan profile is highly affected by erosion during operation. This erosion leads to a deformation of the leading edge shape and a reduction of the chord length. In the present experimental and numerical study, the aerodynamic perfomance of an original fan profile geometry is compared to an eroded fan profile with a blunt leading edge and a chord length reduced by about 1 percent. The experiments are performed at a linear fan blade cascade in the Transonic Cascade Wind Tunnel of DLR in Cologne. The inflow Mach number during the tests is 1.25 and the Reynolds number 1.5 × 106. All tests are carried out at a low inflow turbulence level of 0.8 percent. The results of the investigation show that losses are increased over the whole operating range of the cascade. At the aerodynamic design point the losses raise by 25 percent. This significant loss increase can be traced back to the increase of the shock losses at the leading edge. The change in shock structure is investigated and described in detail by means of PIV measurements and Schlieren imaging. Additionally, the unsteady fluctuation of the shock position is measured by a high speed shadowgraphy. Then the frequency range of the fluctuation is obtained by a Fourier analysis of the time resolved shock position. Furthermore, liquid crystal measurements are performed in order to analyze the influence of the leading edge shape on the development of the suction side boundary layer. The results show that for the original fan blade the transition occurs at the shock position on the blade suction side by a separation bubble whereas the transition onset is shifted upstream for the fan blade with the blunt leading edge.

The Effect of an Eroded Leading Edge on the Aerodynamic Performance of a Transonic Fan Blade Cascade

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Alexander Hergt ◽  
J. Klinner ◽  
W. Steinert ◽  
S. Grund ◽  
M. Beversdorff ◽  
...  
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Separation Bubble ◽  
Leading Edge ◽  
Suction Side ◽  
Aerodynamic Performance ◽  
Chord Length ◽  
Blade Cascade ◽  
Shock Position ◽  
Fan Blade

Especially at transonic flow conditions the leading edge shape influences the performance of a fan profile. At the same time the leading edge of a fan profile is highly affected by erosion during operation. This erosion leads to a deformation of the leading edge shape and a reduction of the chord length. In the present experimental and numerical study, the aerodynamic performance of an original fan profile geometry is compared to an eroded fan profile with a blunt leading edge (BLE) and a chord length reduced by about 1%. The experiments are performed at a linear fan blade cascade in the Transonic Cascade Wind Tunnel of DLR in Cologne. The inflow Mach number during the tests is 1.25 and the Reynolds number 1.5 × 106. All tests are carried out at a low inflow turbulence level of 0.8%. The results of the investigation show that losses are increased over the whole operating range of the cascade. At the aerodynamic design point (ADP) the losses raise by 25%. This significant loss increase can be traced back to the increase of the shock losses at the leading edge. The change in shock structure is investigated and described in detail by means of particle image velocimetry (PIV) measurements and Schlieren imaging. Additionally, the unsteady fluctuation of the shock position is measured by a high-speed shadowgraphy. Then the frequency range of the fluctuation is obtained by a Fourier analysis of the time resolved shock position. Furthermore, liquid crystal measurements are performed in order to analyze the influence of the leading edge shape on the development of the suction side boundary layer. The results show that for the original fan blade the transition occurs at the shock position on the blade suction side by a separation bubble whereas the transition onset is shifted upstream for the fan blade with the BLE.

Application of Laser Interferometry for Transient Film Thickness Measurements

Volume 1 ◽  
2004 ◽  
Author(s):  
Peter Kelly-Zion ◽  
William Collins ◽  
Diana Glawe
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Silicone Oil ◽  
Laser Interferometry ◽  
Bottom Surface ◽  
Glass Slides ◽  
Helium Neon Laser ◽  
Thickness Measurements ◽  
Helium Neon ◽  
Transient Measurements

A laser interferometry technique for making transient measurements of film thickness of the order of 10 to more than 1000 μm is described. The basis for these measurements was reported previously [1] but the technique was applied to solid glass slides and a slowly thinning silicone oil film. The current work describes an adaptation of the technique for the measurement of rapidly changing film thickness, as occurs with evaporating films. A beam from a helium-neon laser is focused on the film at an oblique angle. Some of the laser light is reflected off of the top surface of the film and some is reflected off of the bottom surface. The light reflected from the two surfaces forms a concentric interference fringe pattern which is projected onto a screen and recorded by a high-speed camera. The film thickness is directly related to the spacing of the fringes. To demonstrate the technique, measurements of the time-varying thickness of three evaporating films are presented and experimental considerations are discussed.

STABILITY OF SYMMETRIC BILATERAL DC DISCHARGE IN A RING HELIUM-NEON LASER

2019 ◽  
Vol 69 ◽  
pp. 193-201
Author(s):  
M.V. Chirkin ◽  
◽  
S.V. Ustinov ◽  
V.Yu. Mishin ◽  
◽  
...  
Keyword(s):  
Neon Laser ◽  
Dc Discharge ◽  
Helium Neon Laser ◽  
Helium Neon
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