Rayleigh scattering diagnostic for measurement of velocity and density fluctuation spectra

Development of a Rayleigh Scattering Diagnostic for Time-Resolved Gas Flow Velocity, Temperature, and Density Measurements in Aerodynamic Test Facilities

“…This system was also used to set the fringe diameter of the incident reference light to 13 mm, as determined from the uncertainty analysis. Further details regarding the mirror stabilization system for the FPI can be found in [17].…”

“…The Rayleigh measurements were acquired at 16 and 32 kHz sampling rates, whereas the coldwire instrumentation was limited to a sampling rate of 1 kHz. All three flow parameters (ρ, T, u k ) were measured using the Rayleigh technique, however only temperature results are presented here since the velocity fluctuations were expected to be very small and the density measurement is trivial and has been demonstrated in previous work [17,28]. Simulated temperature data was generated assuming a flow response consisting of a summation of sinusoidal functions at the fundamental frequency of 100 Hz and three additional harmonic frequencies using Eq.…”

“…Previous works using molecular Rayleigh scattering to make temperature, velocity, and number density measurements in harsh environments [12][13][14][15], and dynamic density and velocity measurements in supersonic free jets [16,17] have been reported. The current work describes further development and validation of a technique previously reported in [18] and [19] in which dynamic temperature, velocity, and density measurements were made in a low speed heated jet and an acoustically driven flow up to 16 kHz.…”

Dynamic measurement of temperature, velocity, and density in hot jets using Rayleigh scattering

“…Previous works using molecular Rayleigh scattering to make temperature, velocity, and number density measurements in various environments (Lock et al 1992, Panda & Seasholtz 1999, Mielke et al 2005, and dynamic density and velocity measurements in supersonic free jets (Seasholtz et al 2002) have been reported. The technique described in this paper has been demonstrated previously in various lab-scale flow studies and validated by comparison with hotwire and coldwire probe measurements (Mielke 2008).…”

Multiple-Point Mass Flux Measurement System Using Rayleigh Scattering

“…Using an optical fiber to collect the Rayleigh scattered light provides point-wise or spatially-averaged measurements over a finite distance (on the order of 1.0 mm) along a focused laser beam. Our research group at NASA Glenn Research Center has developed several fibercoupled point-wise Rayleigh scattering measurement systems that are capable of acquiring data at high sampling rates using high quantum efficiency detectors [8][9][10] . Although single-point time-resolved measurements are quite useful, there are many situations that would benefit from multiple-point measurements, especially if these can be acquired at high sampling rates.…”