Characterization of Supersonic Combuster Inlet Flows Using Diode Laser Absorption Spectroscopy

Wittig, Sven; O’Byrne, Sean

doi:10.2514/6.2011-73

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…The results presented in O'Byrne (2010) and Wittig and O'Byrne (2011) showed significant noise on the signal. In O'Byrne (2010) two plausible explanations for this additional noise during the tunnel tests were presented: beam steering due to density variations along the laser path and mechanical vibrations in the model.…”

Section: Physical Response Testsmentioning

confidence: 99%

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Diode Laser Sensor for Scramjet Inlets

O’Byrne¹,

Wittig²,

Kurtz³

et al. 2011

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Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE JUN 20112. REPORT TYPE This work presents test results of a diode-laser sensor for an axially symmetric inlet in a Mach 6 hypersonic flow facility. The conical inlet design presented here is more realistic than the flat plate design presented in the previous report, and is similar to the design that will be chosen as part of the Australian Space Research Program SCRAMSPACE flight test scheduled for 2012. The optical system was changed for this study to make the pitch and catch optics less sensitive to vibration, and to fit into a smaller volume than for the previous test. In addition, wavelength modulation detection was attempted with the system. Initial tests of the conical inlet design showed that it was not starting, as indicated using flow visualization images. The second version of the sensor has similar velocity sensitivity to the system used for the flat plate inlet test. The conical system was, however, still too susceptible to amplitude noise, which hinders the ability of the system to measure the free stream temperature or the angle of attack. Electrical problems with the log-ratio amplifier prevented temperature measurements for the vehicle. Preliminary vibration tests have shown that the problem is caused by independent motion between the laser and collimator when the tunnel fires. A preliminary design of a low-power lock-in amplifier for use in field experiments was completed, and tests with current inputs in place of photodiodes proved successful. SUBJECT TERMS

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Section: Physical Response Testsmentioning

confidence: 99%

“…Velocity was calculated in the same manner as for the flat-plate inlet, and the method is explained in detail in O'Byrne (2010) and Wittig and O'Byrne (2011). An offset signal was subtracted from each spectrum and Gaussian absorbance distributions were fitted to each of the two measured peaks.…”

Section: Velocity Measurementsmentioning

confidence: 99%

Diode Laser Sensor for Scramjet Inlets

O’Byrne¹,

Wittig²,

Kurtz³

et al. 2011

Self Cite

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“…Because of the high Mach numbers experienced by these vehicles, the combustor entrance conditions are strongly influenced by the inlet's angle of attack [1]. At Mach 8, for example, a small deviation in the angle of attack can change the inlet flow temperatures by 100 K or more [2,3]. Therefore, a rapid, realtime measurement capable of monitoring scramjet inlet flow conditions as they vary dramatically on very short time scales is needed.…”

Section: Introductionmentioning

confidence: 99%

Rugged, Scramjet Inlet Temperature and Velocity Sensor: Design and Ground Test

et al. 2016

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The design and testing of a gas temperature and velocity scramjet engine inlet sensor based on tunable diode laser absorption spectroscopy of oxygen is discussed. The robustness and stability of the optical design necessitated by the dynamic vibrational and thermal environment were balanced against the need for compact size and very high signalto-noise ratio in a low-pressure, high-altitude flight regime. Test results demonstrated very good mechanical and thermal stability and an adequate signal-to-noise ratio for altitudes up to 30 km with predicted O 2 absorbance peaks greater than the signal standard deviation by a factor of more than 3. Nomenclature I, I 0 = signal intensity with and without sample gas (arbitrary units) T= I∕I 0 , sample gas transmittance

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