Temperature Profiling of the Atmosphere from an Airborne Lidar by Dispersed Filtered Rayleigh Scattering in Atomic and Molecular Vapors

Rekhy, Anuj; Gerakis, Alexandros; Feng, David; Shneider, Mikhail N.; Dogariu, Arthur; Miles, Richard B.

doi:10.2514/6.2019-3286

Cited by 4 publications

(4 citation statements)

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“…This distribution around ν c depends on (i) the properties of the scattering gas, for example, number density N, pressure P, or temperature T, and (ii) the experimental setup, including the observation angle θ. In all, equation (1) shows that E is directly proportional to N and a function of the other properties ν c , θ, P, T, ⃗ V, . .…”

Section: Motivating Application: Filtered Rayleigh Scattering Of a Sh...mentioning

confidence: 99%

“…For our implementation of SVSA, details of SVR can be found online. 1 The notation 'Σ−φ' in equation ( 5) denotes the S × 1 vector where…”

Section: Overview Of the Svsa Modelmentioning

confidence: 99%

“…For each experimental setup (θ and ν c ), we will calculate the measured light intensity E at each point by inputting the simulated flow parameters into equation (1). In order to capture the important small-scale fluid structures in this flow, the RANS simulations have been calculated over an x-y-z grid at a resolution of 333 × 53 × 70.…”

Section: Optimization Of An Frs Experiments Of a Complex Flow-fieldmentioning

confidence: 99%

“…Rayleigh-Brillouin (RB) scattering has been broadly utilized in laser-based gas diagnostic techniques to non-intrusively measure gas properties and transport coefficients across a diverse set of fields, including atmospheric science, combustion, physics, and oceanography [1][2][3][4][5][6][7][8][9][10][11][12][13]. The widespread use of RB scattering stems from the wealth of information about the scattering gas that such measurements can provide, as the scattered light intensity is proportional to number density, the spectral lineshape (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Fast approximations of spectral lineshapes to enable optimization of a filtered Rayleigh scattering experiment

Hunt

Ground

Hunt

2020

Meas. Sci. Technol.

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Measuring the properties of scattered light is central to many laser-based gas diagnostic techniques, such as filtered Rayleigh scattering (FRS). Alongside the measurements, a model of the scattered light’s spectral lineshape is often used to extract quantitative information about the flow field like pressure, temperature, and velocity. In particular, the Tenti S6 or S7 model are frequently used to model the lineshape of Rayleigh–Brillouin (RB) scattered light. While accurate, it is well attested in the literature that these models can be computationally expensive when evaluated many times, for example, as part of iterative estimation or optimization routines. To overcome this, approximations of these spectral lineshape models can be used instead. In this paper, we develop a method called support vector spectrum approximation (SVSA). This method uses support vector regression and singular value decomposition to create efficient, accurate, and well-conditioned approximations of any existing spectral lineshape model. The SVSA framework improves upon existing approximation methods by allowing quick calculation of spectral lineshapes for arbitrary flow regimes with any number of input parameters over a wide range of values. We demonstrate the efficacy of SVSA in approximating coherent and spontaneous RB scattering spectra. In application, we use SVSA to optimize the design of a filtered Rayleigh scattering experiment of a complex shock-dominated flow. SVSA allows us to comprehensively minimize expected measurement uncertainty of number density and temperature for this experiment. It does this by enabling a high-resolution design of experiments that is otherwise intractable.

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Section: Motivating Application: Filtered Rayleigh Scattering Of a Sh...mentioning

confidence: 99%

“…For our implementation of SVSA, details of SVR can be found online. 1 The notation 'Σ−φ' in equation ( 5) denotes the S × 1 vector where…”

Section: Overview Of the Svsa Modelmentioning

confidence: 99%

Section: Optimization Of An Frs Experiments Of a Complex Flow-fieldmentioning

confidence: 99%