Motion-deblurred, fast-response pressure-sensitive paint on a rotor in forward flight

Juliano, Thomas J.; Disotell, Kevin J.; Gregory, James W.; Crafton, Jim; Fonov, Sergey

doi:10.1088/0957-0233/23/4/045303

Cited by 44 publications

(32 citation statements)

References 24 publications

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“…A deblurring tool developed by Juliano et al (2012) was implemented in MATLAB. The Image Processing Toolbox includes built-in functions that deconvolve an image with a point-spread function describing the motion blur pattern in order to produce a blur-free image.…”

Section: Deblurring Filtermentioning

confidence: 99%

“…Thus, it was acceptable to measure average temperature changes on the blade with TSP and to use the hover temperature field to reduce the PSP data in forward flight. Juliano et al (2012) measured the blade temperature on a steady rotor with an infrared (IR) camera. Though effective, its drawbacks include having an optical window which transmits IR wavelengths (such as a sapphire window) and the blade images are prone to blurring from typically long exposures.…”

Section: Temperature Correctionmentioning

confidence: 99%

“…Blurring artifacts are most pronounced near the edges of the blade and must be corrected to uncover the critical pressure information existing in these regions, such as the signature of a leading-edge vortex. To address the issue of image blurring, Juliano et al (2012) presented a rectilinear deconvolution filter for PSP data which was validated by experiments on a rotating disk.…”

Section: Introductionmentioning

confidence: 99%

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Single-shot temperature- and pressure-sensitive paint measurements on an unsteady helicopter blade

et al. 2014

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Unsteady pressure-sensitive paint (PSP) measurements were acquired on an articulated model helicopter rotor of 0.26 m diameter in edgewise flow to simulate forward flight conditions. The rotor was operated at advance ratios (free stream velocity normalized by hover tip speed) of 0.15 and 0.30 at a cycle-averaged tip chord Reynolds number of 1.1 9 10 5 , with collective and longitudinal cyclic pitch inputs of 10°and 2.5°, respectively. A single-shot data acquisition technique allowed a camera to record the paint luminescence after a single pulse of high-energy laser excitation, yielding sufficient signal-tonoise ratio to avoid image averaging. Platinum tetra(pentafluorophenyl) porphyrin (PtTFPP) in a porous polymer/ ceramic binder served as the PSP. To address errors caused by image blurring and temperature sensitivity, a previously reported motion deblurring algorithm was implemented and the temperature correction was made using temperature-sensitive paint measurements on a second rotor blade. Instantaneous, unsteady surface pressure maps at a rotation rate of 82 Hz captured different aerodynamic responses between the two sides of the rotor disk and were compared to the nominally steady hover case. Cycle-to-cycle variations in tip unsteadiness on the retreating blade were also observed, causing oblique pressure features which may be linked to three-dimensional stall.

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Section: Deblurring Filtermentioning

confidence: 99%

Section: Temperature Correctionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Single-shot temperature- and pressure-sensitive paint measurements on an unsteady helicopter blade

et al. 2014

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“…This technique was first developed by Asai et al (1998) and was further improved to resolve flow phenomena with large dynamic ranges, see Gregory et al (2007), Kameda et al (2005), Mérienne et al (2004), Sakaue et al (2006), Singh et al (2011). A second approach is the application of an emulsion to the model surface, which becomes a highly porous structure after drying, see Asai et al (2001), Juliano et al (2012), Klein et al (2010). In both cases, the active polymer is later anchored directly into the porous structure either by dipping or by spraying.…”

Section: Introductionmentioning

confidence: 99%

Characterization of pressure dynamics in an axisymmetric separating/reattaching flow using fast-responding pressure-sensitive paint

et al. 2012

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This collaborative work discusses the results of time-resolved pressure-sensitive paint measurements performed on a model of a generic spacecraft under sub-and transonic test conditions. It is shown that optical pressure measurements using an active layer from platinumporphyrin complexes (PtTFPP) in combination with a polymer-ceramic base layer are able to measure dynamic flow phenomena in the trisonic wind tunnel facility up to sampling rates of 2 kHz. Low amplitude fluctuations in the order of 0.1 kPa were determined by means of this measurement technique. The buffet dynamics, as well as the spatial extent of the recirculation area in the near-wake, compare well with numerical predictions and PIV measurements. Furthermore, characteristic coherent pressure modes on the base were resolved, which were predicted by large-eddy simulations.

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“…Juliano, et al, 29 have developed a method to deconvolute this type of blurring from an image by using a Point Spread Function (PSF) for the blur. Construction of the PSF for the blurred rotor blade was constructed by first assuming the luminescent intensity decay was first order where I is the intensity, I 0 is the initial intensity at the excitation peak, t is time, and τ is the excited state lifetime of the luminescent material.…”

Section: A Improvements From Using Laser-based Data Acquisitionmentioning

confidence: 99%

Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

Watkins

Leighty

Lipford

et al. 2012

28th Aerodynamic Measurement Technology, Ground Testing, and Flight Testing Conference

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This paper will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14-by 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired using a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. Preliminary results show that the PSP agrees both qualitatively and quantitatively with both the expected results as well as with the pressure transducers. Several areas of improvement have been indentified and are currently being developed for future testing.

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Motion-deblurred, fast-response pressure-sensitive paint on a rotor in forward flight

Cited by 44 publications

References 24 publications

Single-shot temperature- and pressure-sensitive paint measurements on an unsteady helicopter blade

Single-shot temperature- and pressure-sensitive paint measurements on an unsteady helicopter blade

Characterization of pressure dynamics in an axisymmetric separating/reattaching flow using fast-responding pressure-sensitive paint

Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight

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