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  • One-dimensional temperature measurement of supersonic jet flow by resonantly ionized photoemission thermometry of molecular nitrogen
Title: One-dimensional temperature measurement of supersonic jet flow by resonantly ionized photoemission thermometry of molecular nitrogen
As the field of fluid dynamics progresses, the demand for sophisticated diagnostic methods to accurately assess flow conditions rises. In this work, resonantly ionized photoemission thermometry (RIPT) has been used to directly target and ionize diatomic nitrogen (N2) to measure one-dimensional (1D) temperature profiles in a supersonic jet flow. This technique can be considered non-intrusive as the premise uses resonantly enhanced multiphoton ionization (REMPI) to target molecular nitrogen. This resonance excites N2into absorption bands of the P, Q, and R rotational branches of N2(b1Πu). The ideal (3 + 1) REMPI scheme excites from the ground state and ionizes N2(b1Πu←X1Σg+) where de-excitation results in photoemission from the first negative band of ionizedN2+(B2Σu+→X2Σg+) as nitrogen returns to the ground state. The resulting emission can be observed using an intensified camera, thus permitting inference of the rotational temperature of ground-state molecular nitrogen. A linearly regressive Boltzmann distribution is applied based on previous calibration data for this technique to quantify the temperature along the ionized line. This work applies this technique to a pure N2supersonic jet in cross-flow and counter-flow orientations to demonstrate N2RIPT’s applications in a supersonic flow. Temperature variations are observed at different locations downstream of the exit in cross-flow, and axisymmetric in counter-flow, to generate profiles characterizing the flow dynamics. Due to the collisional effects resulting from the number density of N2at higher pressures, a (3 + 2) REMPI scheme is observed throughout this text.  more » « less
Award ID(s):
2409331 2026242
PAR ID:
10615948
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Optics Continuum
Date Published:
Journal Name:
Optics Continuum
Volume:
4
Issue:
1
ISSN:
2770-0208
Page Range / eLocation ID:
1
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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