Shock-Train Structure Resolved with Absorption Spectroscopy Part I: System Design and Validation

Lindstrom, C. D.; Jackson, Kevin; Williams, Skip; Givens, Ryan N.; Bailey, William F.; Tam, Chung-Jen; Terry, W.

doi:10.2514/1.41074

Cited by 27 publications

(16 citation statements)

References 30 publications

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“…As spatial resolved temperature measurement capability developed combining with its high time response character, absorption technique will advance the research of supersonic combustor design. 12,13 …”

Section: Discussionmentioning

confidence: 99%

Measurement of temperature, velocity and water vapor concentration in a scramjet combustor based on near-infrared diode laser absorption

et al. 2011

17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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A multi-channel Tunable Diode Laser Absorption Spectroscopy (TDLAS) system was designed and constructed for flow parameters diagnostics in a scramjet combustor. Two fiber coupled distributed feedback (DFB) lasers with narrow line width were used to probe two H 2 O absorption features (7185.597cm (combined)) by using direct absorption Time-Division-Multiplexing (TDM) strategy at a 4-kHz repetition rate. Laser light was split into five beams and transmitted across the test region. Two motorized precision translation stages were used to move the collimators during the test, so that the three beams located near the cavity and at the exit of the combustor can scan the cross sections respectively. Flow parameters could be obtained simultaneous which included average temperature, water vapor concentration and velocity at the entrance of the combustor, the distribution of temperature, water vapor concentration at a cross section near the cavity, the distribution of temperature, water vapor concentration and velocity at the exit cross section of the combustor. The parameters of the flow entering and exiting the combustor could be used to evaluate the performance of the direct-connected scramjet facility and the combustion efficiency of the combustor. The parameters at the cross section in the combustor could also be used to analysis combustion characteristics in the combustor.

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Section: Discussionmentioning

confidence: 99%

Measurement of temperature, velocity and water vapor concentration in a scramjet combustor based on near-infrared diode laser absorption

et al. 2011

17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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“…Consequently, many variations of the TDLAS diagnostic have been successfully demonstrated for in situ measurements of various flow parameters in scramjet test facilities [11][12][13][14][15][16][17]. For instance, Upschultep et al [11] measured velocity, static temperature, and water vapor concentration at the inlet of the combustor in a direct-connected test facility.…”

Section: Introductionmentioning

confidence: 99%

“…Gruber et al [15] used two water absorption lines to measure water vapor concentration and static temperature at nine fixed vertical positions near the combustor exit. Lindstrom et al [16] studied the shock train structure in a rectangular isolator using multiple line-of-sight absorption measurements. Rieker et al [17] demonstrated a three-wavelength tunable diode-laser temperature sensor to study combustion instabilities.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous measurements of multiple flow parameters for scramjet characterization using tunable diode-laser sensors

et al. 2011

Appl. Opt.

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This paper reports the simultaneous measurements of multiple flow parameters in a scramjet facility operating at a nominal Mach number of 2.5 using a sensing system based on tunable diode-laser absorption spectroscopy (TDLAS). The TDLAS system measures velocity, temperature, and water vapor partial pressure at three different locations of the scramjet: the inlet, the combustion region near the flame stabilization cavity, and the exit of the combustor. These measurements enable the determination of the variation of the Mach number and the combustion mode in the scramjet engine, which are critical for evaluating the combustion efficiency and optimizing engine performance. The results obtained in this work clearly demonstrated the applicability of TDLAS sensors in harsh and high-speed environments. The TDLAS system, due to its unique virtues, is expected to play an important role in the development of scramjet engines.

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“…Its abundance, coupled with the large line strengths for the vibrational bands in the near infrared makes it suitable for absorption spectroscopy studies in scramjet isolators, combustors and exhausts. Researchers in Australia and the United States have developed TDLAS systems for scramjet combustion monitoring [13,14,15,16,17,18]. Stanford University researchers recently undertook wavelength-multiplexed two-colour TDLAS to measure H 2 O temperature and column density in a model scramjet combustor under high enthalpy conditions generated in a reflected shock tunnel [19].…”

Section: Tunable Diode Laser Absorption Spectroscopymentioning

confidence: 99%

“…These criteria have since been adopted by various authors [14,13,16,17,53,54,55] and are accepted for this study as being the state of the art.…”

Section: Wavelength Selectionmentioning

confidence: 99%

Tunable Diode Laser Absorption Spectroscopy of Aerospace Flows

Wheatley¹

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Direct and wavelength modulated methods of tunable diode laser absorption spectroscopy (TDLAS) techniques were applied to hypersonic and rarefied gas environments. Three experimental campaigns are discussed including direct absorption spectroscopy of a steam ejector flow, wavelength modulated TDLAS of scramjet combustion in an expansion tunnel, and temperature measurement of atomic oxygen in a plasma generator. The literature relevant to TDLAS is reviewed and the theoretical bases for the two techniques are presented. Each campaign required innovative solutions to experimental problems but, in the end, TDLAS was successfully applied on a proof-of-concept basis in each environment. The pressure and temperature in a 1 kms −1 steam ejector flow were measured using direct TDLAS.Three methods of analysing the data were compared for accuracy and ease of use. The best method was found to be using the Levenburg-Marquardt method to perform a non-linear least-squares minimisation of the residual between a Voigt fit of simulated and measured data. Absolute average residual errors of less than 0.1% were achieved together with pressure relative error of ±2% and temperature errors of ±10 K. Wavelength modulated TDLAS was investigated as a means to measure parameters in the combustor and nozzle of a scramjet in an expansion tunnel. The scramjet operated at an inlet Mach number of approximately 10 and a static pressure of 120 Pa simulating flight at approximately 30 km altitude. The test time was of the order of 1 ms. Hydrogen fuel was injected via five holes in the scramjet inlet ramp. Two laser diodes operating near 1392 nm were used to probe the scramjet nozzle flow. The lasers were simultaneously sinusoidally modulated in power and wavelength at a frequency near 1.0 MHz. Tests were conducted at various fuel injection pressures into both air and nitrogen test gas.Combustion was detected in the scramjet nozzle. Results are presented together with recommendations for future research. The atomic oxygen concentration in a microwave generated plasma generated by an Evenson cavity was measured using TDLAS to probe the oxygen triplet at 844.6 nm. The oxygen atoms in the plasma were highly excited and emitted radiation that could have overwhelmed the laser absorption. Any spectral features were expected to be narrow as the plasma pressure was between 80 Pa and 300 Pa. The measured intensity ratios were used to calculate the number density of oxygen atoms in the upper states with a relative error of approximately 5%. The calculated number density, mole fraction of atomic oxygen and intensity ratio were highly sensitive to the temperature as was expected given the exponential form of Boltzmann's equation. A brief analysis was also presented of a TDLAS system that could detect atomic oxygen in reflected shock or expansion tunnel experiments. Whilst the system was not implemented for this study, the information presented may assist future researchers to develop an atomic oxygen TDLAS system for free-piston hypersonic tunnels. Th...

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Shock-Train Structure Resolved with Absorption Spectroscopy Part I: System Design and Validation

Cited by 27 publications

References 30 publications

Measurement of temperature, velocity and water vapor concentration in a scramjet combustor based on near-infrared diode laser absorption

Measurement of temperature, velocity and water vapor concentration in a scramjet combustor based on near-infrared diode laser absorption

Simultaneous measurements of multiple flow parameters for scramjet characterization using tunable diode-laser sensors

Tunable Diode Laser Absorption Spectroscopy of Aerospace Flows

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