Rotational Raman-based temperature measurements in a high-velocity, turbulent jet

Locke, Randy J.; Wernet, Mark P.; Anderson, Robert C.

doi:10.1088/1361-6501/aa934d

Cited by 13 publications

(23 citation statements)

References 25 publications

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“…Step II tests consisted of acquiring Raman temperature measurements, using the same laser/optical hardware applied in the work reported here, in the flow of a 50.8 mm diameter heated jet operated over a range of temperatures and Mach numbers [Locke & Wernet, 2017]. The Raman temperature data were compared with an existing database of PIV data in similar flows enabling assessment of LES predictions of flow velocity, turbulence, mean temperature and rms temperature [Debonis, 2017].…”

Section: Project Descriptionmentioning

confidence: 99%

“…Rotationally resolved Raman scattering has been previously used to measure gas temperature in heated high speed jet flows in the SHJAR facility at NASA GRC [Locke et al, 2017]. A thorough discussion of Raman spectroscopy theory and practices can be found in Ferraro and Nakamoto [18].…”

Section: Raman Scatteringmentioning

confidence: 99%

“…The number of populated states increases with temperature, hence the rms temperature increases with increasing temperature of the gas. This is a known and documented characteristic of the technique, which is actually a systematic measurement error [Locke et al, 2017]. A calibration of the Raman system in a well characterized environment free from flow turbulence of other noise sources is required in order to characterize this inherent rms temperature variation in the technique.…”

Section: Raman System Calibrationmentioning

confidence: 99%

“…Vibrational Raman is ineffective in low temperature regimes due to the lack of the anti-Stokes bands; however, pure rotational Raman spectroscopy, which is not dependent upon anti-Stoke lines, has been used to interrogate expanding supersonic flows of CO2 for measuring temperature [Maté, et al, 1998]. Rotationally resolved Raman has more recently been used to acquire mean and rms temperature measurements in high temperature flows, from subsonic to supersonic speeds in harsh real world test facilities [Locke &Wernet, 2017]. Rotationally resolved Raman scattering is the only technique which is simple to setup/align and robust against the hostile environments found in real world aerospace simulation facilities; therefore it is the technique of choice for measuring the gas temperatures in thin film cooling -shear layer flows of interest in this work.…”

Section: Introductionmentioning

confidence: 99%

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PIV and Rotational Raman-Based Temperature Measurements for CFD Validation in a Single Injector Cooling Flow

Wernet

Georgiadis

Locke

2018

2018 Fluid Dynamics Conference

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Film cooling is used in a wide variety of engineering applications for protection of surfaces from hot or combusting gases. The design of more efficient thin film cooling geometries/configurations could be facilitated by an ability to accurately model and predict the effectiveness of current designs using computational fluid dynamics (CFD) code predictions. Hence, a benchmark set of flow field property data were obtained for use in assessing current CFD capabilities and for development of better turbulence models. Both Particle Image Velocimetry (PIV) and spontaneous rotational Raman scattering (SRS) spectroscopy were used to acquire high quality, spatially-resolved measurements of the mean velocity, turbulence intensity and also the mean temperature and normalized root mean square (rms) temperatures in a single injector cooling flow arrangement. In addition to flowfield measurements, thermocouple measurements on the plate surface enabled estimates of the film effectiveness. Raman spectra in air were obtained across a matrix of radial and axial locations downstream from a 68.07 mm square nozzle blowing heated air over a range of temperatures and Mach numbers, across a 30.48cm long plate equipped with a single injector cooling hole. In addition, both centerline streamwise 2-component PIV and cross-stream 3-component Stereo PIV data at 15 axial stations were collected in the same flows. The velocity and temperature data were then compared against Wind-US CFD code predictions for the same flow conditions. The results of this and planned follow-on studies will support NASA's development and assessment of turbulence models for heated flows.

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Section: Project Descriptionmentioning

confidence: 99%

Section: Raman Scatteringmentioning

confidence: 99%

Section: Raman System Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PIV and Rotational Raman-Based Temperature Measurements for CFD Validation in a Single Injector Cooling Flow

Wernet

Georgiadis

Locke

2018

2018 Fluid Dynamics Conference

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“…SRS is traditionally used for measurement in stationary media because it requires long acquisition times (seconds to minutes) due to weakness of the Raman cross section. Single shot capability of spontaneous Raman thermometry has also been demonstrated using high energy pulsed lasers (~500 mJ per pulse). However, they operate at low repetition rate (~10 Hz) and are unable to probe fast temporal dynamics.…”

Section: Introductionmentioning

confidence: 99%

Spontaneous rotational Raman thermometry for air flow characterization in a turbomachine test rig

Scherman

Santagata

Faleni

et al. 2019

J Raman Spectroscopy

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Noninvasive and accurate measurements are essential to study the reactive flows in aeronautical engines. This paper reports the results of a unique measurement campaign providing the temperature flow field in a large‐scale facility turbomachine test rig using spontaneous rotational Raman scattering technique. Different planes of interest and operating conditions are probed, showing good agreement with thermocouple measurements. Fast temperature variations (>7.7 kHz) could be probed thanks to synchronization of the laser pulse with the rotor clock. The results outline the performance of in situ Raman technique to investigate steady and unsteady flows in turbine's conditions.

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Raman temperature and density measurements in supersonic jets

Wernet

Georgiadis

Locke³

2021

Exp Fluids

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Prediction of flow-field properties in supersonic jets using computational fluid dynamics (CFD) code predictions has become routine; however, obtaining accurate solutions becomes more challenging when there is a significant temperature difference between the jet core and the ambient air and/or compressibility effects are significant. Benchmark sets of flow field property data are required in order to assess current CFD capabilities and develop better modeling approaches for these turbulent flow fields where accurate calculation of temperatures and turbulent heat flux is important. Particle Image Velocimetry, spontaneous rotational Raman scattering spectroscopy, and Background-Oriented Schlieren (BOS) have been previously used to acquire measurements of the mean and root-mean-square (rms) velocities, the mean and rms gas temperatures, and density gradients in subsonic jet flows and film cooling flows. In this work, the ability to measure density is added to the list of measurands available using the acquired Raman spectra. The suite of measurement techniques are now applied to supersonic jet flows. The computation of the local gas pressure in the potential core of an over-expanded jet is demonstrated using the Raman measured gas temperature and density. Additionally, a unique density feature in temperature matched, perfectly expanded jet flow shear layers identified using BOS was verified using the Raman measurement technique. These non-intrusive flow measurements are compared against RANS predictions of the supersonic jet flow properties as a means of assessing their prediction accuracy. Graphic abstract

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Rotational Raman-based temperature measurements in a high-velocity, turbulent jet

Cited by 13 publications

References 25 publications

PIV and Rotational Raman-Based Temperature Measurements for CFD Validation in a Single Injector Cooling Flow

PIV and Rotational Raman-Based Temperature Measurements for CFD Validation in a Single Injector Cooling Flow

Spontaneous rotational Raman thermometry for air flow characterization in a turbomachine test rig

Raman temperature and density measurements in supersonic jets

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