Fluorescence Imaging of Rotational and Vibrational Temperature in Shock-Tunnel Nozzle Flow

Abstract

Two-dimensional rotational and vibrational temperature measurements were made at the nozzle exit of a free-piston shock tunnel using Planar Laser-Induced Fluorescence. The Mach 7 flow consisted predominantly of nitrogen with a trace quantity of nitric oxide. Nitric oxide was employed as the probe species and was excited at 225 run. Non-uniformities in the distribution of nitric oxide in the test gas were observed, and concluded to be due to contamination of the test gas by driver gas or cold test gas. The nozzle-exit rotational temperature was measured and is in reasonable agreement with computational modelling. Non-linearities in the detection system were responsible for systematic errors in the measurements. The vibrational temperature was measured to be constant with distance from the nozzle exit, indicating it had frozen during the nozzle expansion.

Abel inversion of axially-symmetric shock wave flows

“…Based on this assumption, the code determines the flow at the exit of the nozzle to have an effective ratio of specific heats of 1.33. Having said this, it is important to note that Palma et al [8] show that the rotational and vibrational temperatures differ significantly in the hypersonic nozzle flows of free-piston shock tunnels. Hence, the assumption of thermal equilibrium is expected to result in systematic errors in the calculated flow conditions.…”

Temperature measurements by oh lif and chemiluminescence kinetic modeling for ethanol flames

“…In addition, a photograph of the burner and its heating system used to generate the premixed ethanol flames ( Figure 1S), a scheme of experimental setup for temperature measurements by OH-LIF ( Figure 2S) and a plot of simulated temperature profiles after changes in the kinetic modeling ( Figure 3S) (3), (4), (7), (9), (12), (14), (24), (43), (82) …”

“…LIF-thermometry has been broadly employed to combustion research for accurate temperature determination. [22][23][24][25] The laser diagnostic ensures high spatial resolution without gas-dynamic disturbances into the flame. Furthermore, temperature is also a significant parameter to build reaction mechanisms to combustion modeling.…”

Measurement of Vibrational Nonequilibrium in a Supersonic Freestream Using Dual-Pump CARS

“…Vibrational non-equilibrium in hypersonic facilities has been measured previously in arc jets using spontaneous Raman spectroscopy, 2 and in shock tunnels using nitric oxide planar laser induced fluorescence (NO PLIF) 3 and broadband N 2 coherent anti-Stokes Raman spectroscopy (CARS). 4 It has been included in the calculation of facility freestreams and shock-layer flows.…”