The fuel/air ratio (FAR) in a methane-air Hencken flame at pressures of 1–5 bar is measured using the chemiluminescence-based method. Emission spectra are used to investigate effects pressure on OH* (308 nm), CH* (430 and C2* (500 nm) emissions effect equivalence determination from ratios these emission peaks. Both OH*/CH* C2*/CH* linear FAR atmospheric pressure. At elevated pressures, remains roughly FAR, while becomes highly nonlinear. There significant spectral contributions continuum...

Air resonance enhanced multiphoton ionization (REMPI) tagging velocimetry (ART) was demonstrated in quiescent and supersonic flows. The ART method utilizes a wavelength tunable laser beam to resonantly ionize molecular oxygen air generate additional avalanche-type of nitrogen. fluorescence emissions from the first negative positive bands nitrogen are, thus, produced used for flow tagging. Detailed characterization conducted, including effects fluoresce nitrogen, spectrum, energy deposition...

This paper presents an extensive parameter study of a non-intrusive and non-seeded laser diagnostic method for measuring one dimensional (1D) rotational temperature molecular nitrogen (N 2 ) at 165 - 450 K. Compared to previous efforts using oxygen, here resonantly ionized photoelectron induced fluorescence thermometry RIPT) was demonstrated. The RIPT signal is generated by directly probing various levels within the rovibrational absorption band N , corresponding 3-photon transition ( X 1 Σ...

In this work, a detailed calibration study is performed to establish non-intrusive one-dimensional (1D) rovibrational temperature measurements in unseeded air, based on air resonance enhanced multiphoton ionization thermometry (ART). ART generated by REMPI (resonance multi-photon ionization) of molecular oxygen and subsequent avalanche nitrogen single laser pulse. signal, the fluorescence from first negative band nitrogen, directly proportional 2-photon transition C3Π (v = 2) ← X3Σ (v'=0),...

Characterization of the thermal gradients within supersonic and hypersonic flows is essential for understanding transition, turbulence, aerodynamic heating. Developments in novel, impactful non-intrusive techniques are key enabling flow characterizations sufficient detail that provide experimental validation datasets computational simulations. In this work, Resonantly Ionized Photoemission Thermometry (RIPT) signals directly imaged using an ICCD camera to realize 1D measurement capability...

As the field of fluid dynamics progresses, demand for sophisticated diagnostic methods to accurately assess flow conditions rises. In this work, resonantly ionized photoemission thermometry (RIPT) has been used directly target and ionize diatomic nitrogen (N 2 ) measure one-dimensional (1D) temperature profiles in a supersonic jet flow. This technique can be considered non-intrusive as premise uses enhanced multiphoton ionization (REMPI) molecular nitrogen. resonance excites N into...

One-dimensional (1D) Oxygen-tagging and Nitrogen-tagging Resonantly Ionized Photoelectron Thermometry technique was developed used to characterize linewise thermal gradients present within ambient air, high-speed flows, large-scale Mach 4 Ludwieg tube.

View Video Presentation: https://doi.org/10.2514/6.2023-0222.vid Capturing and understanding of the thermal effects present in supersonic flows is essential for further characterization flow interactions within them. A critical component to be able quantify gradients observed. Characterization temperature changes has recently been demonstrated using a novel, non-intrusive technique. Resonantly ionized photoemission thermometry (RIPT) captures signals that can directly imaged, their intensity...

View Video Presentation: https://doi.org/10.2514/6.2023-0406.vid A detailed calibration study of a non-intrusive, non-seeded one-dimensional (1D) rotational temperature measurement molecular Nitrogen at atmospheric pressure is presented based on resonantly ionized and subsequent photoelectron-induced fluorescence analysis for thermometry (N2 RIPT). The RIPT signal generated via directly probing various peaks within the resonant absorption band corresponding to 3-photon transition N2 (X^1...

View Video Presentation: https://doi.org/10.2514/6.2022-1784.vid The quantification of flow properties in high-enthalpy wind tunnels is a major challenge. complex phenomena occurring these flows are currently poorly understood with few existing diagnostic tools available for quantitative analysis. Therefore, spatially and temporally resolved measurements the plasma hypersonic critically important to ensure accurate modeling physics chemistry. present paper discusses results performed an air...

MUltiplexed Structural Image Capture (MUSIC) technique is implemented to "instantaneously" capture two resulting images with different spatial phases enhance the resolution of recovered images. The MUSIC uses modulation light from a scene prior imaging encode temporal evolution target into frequency shifts, each shift corresponding unique time and in individual distinct snapshots. Computer-processing multiplexed single-shot image can recover nanosecond-resolution evolution. One limitations...

Multiplexed Structured Image Capture (MUSIC) facilitates imaging at frames rates well above camera hardware limits by uniquely masking time-displaced obtained from spatially-displaced optical paths on a single exposure. The speed is therefore theoretically increasable to very high rates, limited only the spatial precision of components' layout. In this work, MUSIC extended frame beyond previously demonstrated 1 GHz as proof-of-concept leading towards design goal near THz. Results two-frame...

In this work, a detailed calibration study is performed to establish non-intrusive 1D rotational temperature measurements based on Air Resonance enhanced multiphoton ionization Thermometry (ART) as technique. First by using coherent microwave scattering (Radar) from REMPI (Resonance Enhanced Multi-Photon Ionization), analysis of the line strengths 2-photon transition molecular oxygen C3Π (v=2) ← X3Σ (v’=0) have been conducted. Experimentally found hyperfine structures O2 branches are then...

In this work, one-dimensional (1D) Oxygen-based Resonantly Ionized Photoelectron Thermometry (O2 RIPT) technique is used for temperature measurements in a M∞ = 4 flow. O2 RIPT resonantly ionizes molecules via (2+1) Resonant Enhanced Multiphoton Ionization (REMPI) process; subsequent ionization electron-impacted avalanche of molecular nitrogen produces fluorescence emissions from the first negative band N2 through photoemission deexcitation. The occur at Δv0, 390nm; Δv2, 425nm; Δv1, 430nm and...

The frame rate of conventional high-speed imaging devices is limited by exposure time and signal read-out time. Structured able to push the beyond limit device. This work demonstrates feasibility potential TeraHz structured with a multiplexed setup. In this work, image capture system was employed UV laser induced krypton-II emission lines at 10 GHz. measured intensity 764 nm line over suggests temporal resolution 97 ps. adjustable, can be further increased level.

Structured and patterned light techniques have recently gained a significant amount of attention for optical imaging measurements. Depending on the application, these can enhance resolution, reduce background noise, allow ultrafast imaging, or enable hyperspectral analysis. Multiplexed structtired image capture (MJSIC) is an technique that uses unique periodic patterning just prior to by camera. The allows information be kept separate in Fourier domain, allowing multiple images...

A single-camera three-dimensional MUltiplexed Structured Image Capture (3D - MUSIC) based stereoscopic imaging system is demonstrated as a new method of obtaining stereo vision pairs without compromising sensor area. The validated via reconstructing stationary target and moving flame. Images from each channel are spatially modulated through two optical paths the resultant image obtained onto an ICCD camera. scene for computationally recovered by MUSIC, i.e., low-pass filtering in spatial...