TY - JOUR
T1 - Improved test time evaluation in an expansion tube
AU - James, Christopher M.
AU - Cullen, Timothy G.
AU - Wei, Han
AU - Lewis, Steven W.
AU - Gu, Sangdi
AU - Morgan, Richard G.
AU - McIntyre, Timothy J.
N1 - Funding Information:
The authors wish to thank: All X2 operators past and present for their support with operating the facility; it would not be possible to keep X2 going without them; Dr. F. Zander for providing his original Canny shock standoff finding code; Mr. F. De Beurs, Mr. N. Duncan, Mr. B.V. Allsop, and the EAIT Faculty Workshop Group for technical support on X2; Mr. F. Saric for developing the new bar gauge used as a second pressure measurement technique for the Zander condition; The Australian Research Council for support and funding; The Queensland Smart State Research Facilities Fund 2005 for support and funding; Ms. E.J. Bourke for reading the paper. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Publisher Copyright:
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - Traditionally, expansion tube test times have been experimentally evaluated using test section mounted impact pressure probes. This paper proposes two new methods which can be performed using a high-speed camera and a simple circular cylinder test model. The first is the use of a narrow bandpass optical filter to allow time-resolved radiative emission from an important species to be captured, and the second is using edge detection to track how the model shock standoff changes with time. Experimental results are presented for two test conditions using an air test gas and an optical filter aimed at capturing emission from the 777 nm atomic oxygen triplet. It is found that the oxygen emission is the most reliable experimental method, because it is shown to exhibit significant changes at the end of the test time. It is also proposed that, because the camera footage is spatially resolved, the radiative emission method can be used to examine the ‘effective’ test time in multiple regions of the flow. For one of the test conditions, it is found that the effective test time away from the stagnation region for the cylindrical test model is at most 45% of the total test time. For the other test condition, it is found that the effective test time of a 54∘ wedge test model is at most a third of the total test time.
AB - Traditionally, expansion tube test times have been experimentally evaluated using test section mounted impact pressure probes. This paper proposes two new methods which can be performed using a high-speed camera and a simple circular cylinder test model. The first is the use of a narrow bandpass optical filter to allow time-resolved radiative emission from an important species to be captured, and the second is using edge detection to track how the model shock standoff changes with time. Experimental results are presented for two test conditions using an air test gas and an optical filter aimed at capturing emission from the 777 nm atomic oxygen triplet. It is found that the oxygen emission is the most reliable experimental method, because it is shown to exhibit significant changes at the end of the test time. It is also proposed that, because the camera footage is spatially resolved, the radiative emission method can be used to examine the ‘effective’ test time in multiple regions of the flow. For one of the test conditions, it is found that the effective test time away from the stagnation region for the cylindrical test model is at most 45% of the total test time. For the other test condition, it is found that the effective test time of a 54∘ wedge test model is at most a third of the total test time.
UR - http://www.scopus.com/inward/record.url?scp=85046683203&partnerID=8YFLogxK
U2 - 10.1007/s00348-018-2540-1
DO - 10.1007/s00348-018-2540-1
M3 - Journal article
AN - SCOPUS:85046683203
SN - 0723-4864
VL - 59
JO - Experiments in Fluids
JF - Experiments in Fluids
IS - 5
M1 - 87
ER -