Interpreting single-point and two-point focused laser differential interferometry in a turbulent jet

Ceruzzi, Andrew; Cadou, Christopher P.

doi:10.1007/s00348-022-03459-w

Cited by 17 publications

(21 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several recent publications discussed the depth-of-field of FLDI in more detail with some particularly focusing on its ability to penetrate turbulent environments around an object of interest. 70,74,76,77 All those sources reveal dependencies of the depth-of-field on the frequency, wavelength, and amplitude of density disturbances within the probed flowfield. Therefore, additional post-processing steps need to added to investigate the performance of the Oxford FLDI system as it is not possible to simply compare the FWHM of the sensitivity at 300 kHz to the beam-wise width of the boundary layer.…”

Section: Depth Of Field Of Fldi Setupmentioning

confidence: 98%

“…As described previously, a particular asset of such laser interferometers is their narrow depth of field. Similarly to Ceruzzi et al, 74 we have characterized the system's response by translating an acoustic fluctuation source along the beams length. Here, this is not a gaseous jet as in Ref.…”

Section: Depth Of Field Of Fldi Setupmentioning

confidence: 98%

“…69 This generates what would be described as "depth-of-field" in a camera 72 and hence concentrates the sensitivity of FLDI in a narrow field in beam wise direction. 67,68,71 Herein, focal lengths of the lenses were specifically selected to match the width of the HDT's test section. Two adjustable mirrors (I) turn the beam by 90 twice to save space next to the test section windows, giving the Oxford FLDI a z-shaped light path.…”

Section: E Focused Laser Differential Interferometry (Fldi)mentioning

confidence: 99%

“…More information about the technique's general working principle can be found in the original publication from Smeets 68 or in theses from Fulghum, 67 Parziale, 70 or Ceruzzi. 71,74 1. Recording and alignment procedure FLDI data acquisition was run for 20 ms and sampled with an oscilloscope at 10 MHz, while the laser was run at full power during a tunnel shot.…”

Section: E Focused Laser Differential Interferometry (Fldi)mentioning

confidence: 99%

“…Here, this is not a gaseous jet as in Ref. 74, but a Multicomp Pro 300 kHz sound transceiver, which was driven by a function generator. It is mechanically traversed Picoscope with differential port along the FLDI light path around the sensitive region in a benchtop investigation at room temperature and atmospheric pressure.…”

Section: Depth Of Field Of Fldi Setupmentioning

confidence: 99%

See 4 more Smart Citations

Displacement of hypersonic boundary layer instability and turbulence through transpiration cooling

Kerth,

Le Page,

Wylie

et al. 2024

Physics of Fluids

Self Cite

View full text Add to dashboard Cite

Hypersonic boundary-layer transition onset is commonly characterized in wind tunnel experiments by measuring the surface heat transfer rise above the laminar level. Techniques such as infrared thermography and thin film gauges are routinely used in the field. However, when an interfering cooling effect is present due to foreign gas transpiration, these methods are known to be inadequate. This study uses a 7° half-angle cone at Mach 7 with helium or nitrogen injection through a porous segment within the model frustum. The injector spans 60° in azimuth and is located 300 mm from the sharp nose tip, close to the onset of natural boundary-layer transition. Nitrogen and helium injection reduce the surface heat flux below the laminar level for up to 50 mm downstream of the injector. Comparisons to schlieren images and pressure measurements indicate an advance of transition. Optical diagnostics reveal how instabilities are pushed away from the model surface by the injected gas. This is found through spectral analysis of schlieren images and focused laser differential interferometry signals, which revealed further information about how inaccuracies of detecting transition with surface gauges under the influence of transpiration cooling originate.

show abstract

Section: Depth Of Field Of Fldi Setupmentioning

confidence: 98%

Section: Depth Of Field Of Fldi Setupmentioning

confidence: 98%