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Toluene-based planar laser-induced fluorescence imaging of temperature in hypersonic flows

Toluene-based planar laser-induced fluorescence imaging of temperature in hypersonic flows
Toluene-based planar laser-induced fluorescence imaging of temperature in hypersonic flows
Planar laser-induced fluorescence imaging is carried out in a hypersonic gun tunnel at a freestream Mach number of 8.9 and Reynolds number of 47.4×106m?1 (N2 is the test gas). The fluorescence of toluene (C7H8) is correlated with the red shift of the emission spectra with increasing temperature. A two-colour approach is used where, following an excitation at 266 nm, emission spectra at two different bands are captured in separate runs using two different filters. Two different flow fields are investigated using this method: (i) hypersonic flow past a blunt nose, which is characterised by a bow shock with strong entropy effects, and (ii) an attached shock-wave/boundary-layer interaction induced by a flare located further downstream on the same blunt cylinder body. Measurements from as low as the freestream temperature of 68.3 K all the way up to 380 K (T??5.6T?) are obtained. The uncertainty at the higher temperature level is approximately ±15 %, while at the low end of the temperature, an additional ±15 % uncertainty is expected. Application of the technique is further challenged at high temperatures due to the exponentially reduced fluorescence quantum yields and the occurrence of toluene pyrolysis near the stagnation region (To=1150 K). Overall, results are found to be within 10 % agreement with the expected distributions, thus demonstrating suitability of the technique for hypersonic flow thermometry applications in low-enthalpy facilities
0723-4864
1-13
Ganapathisubramani, Bharathram
5e69099f-2f39-4fdd-8a85-3ac906827052
Ganapathisubramani, Bharathram
5e69099f-2f39-4fdd-8a85-3ac906827052

Ganapathisubramani, Bharathram (2015) Toluene-based planar laser-induced fluorescence imaging of temperature in hypersonic flows. Experiments in Fluids, 56 (115), 1-13. (doi:10.1007/s00348-015-1987-6).

Record type: Article

Abstract

Planar laser-induced fluorescence imaging is carried out in a hypersonic gun tunnel at a freestream Mach number of 8.9 and Reynolds number of 47.4×106m?1 (N2 is the test gas). The fluorescence of toluene (C7H8) is correlated with the red shift of the emission spectra with increasing temperature. A two-colour approach is used where, following an excitation at 266 nm, emission spectra at two different bands are captured in separate runs using two different filters. Two different flow fields are investigated using this method: (i) hypersonic flow past a blunt nose, which is characterised by a bow shock with strong entropy effects, and (ii) an attached shock-wave/boundary-layer interaction induced by a flare located further downstream on the same blunt cylinder body. Measurements from as low as the freestream temperature of 68.3 K all the way up to 380 K (T??5.6T?) are obtained. The uncertainty at the higher temperature level is approximately ±15 %, while at the low end of the temperature, an additional ±15 % uncertainty is expected. Application of the technique is further challenged at high temperatures due to the exponentially reduced fluorescence quantum yields and the occurrence of toluene pyrolysis near the stagnation region (To=1150 K). Overall, results are found to be within 10 % agreement with the expected distributions, thus demonstrating suitability of the technique for hypersonic flow thermometry applications in low-enthalpy facilities

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More information

Accepted/In Press date: 11 May 2015
e-pub ahead of print date: 27 May 2015
Published date: June 2015
Organisations: Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 377643
URI: http://eprints.soton.ac.uk/id/eprint/377643
ISSN: 0723-4864
PURE UUID: b579e732-0e70-4dff-a295-fccbe985b38f
ORCID for Bharathram Ganapathisubramani: ORCID iD orcid.org/0000-0001-9817-0486

Catalogue record

Date deposited: 18 Jun 2015 08:57
Last modified: 20 Jul 2019 00:46

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