Rocket nozzle cold‐gas flow velocity measurements using laser‐induced gratings

Hemmerling, B.; Neracher, M.; Kozlov,; Kwan, W.; Stark, Ralf; Klimenko, D.; Clauß, W.; Oschwald, Michael

doi:10.1002/jrs.946

Cited by 20 publications

(20 citation statements)

References 6 publications

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“…In non-reacting flows the LIGs technique has already been used to accomplish local temporally-resolved measurements of the gas temperature (e. g. [4,5]), gas dynamic properties (e. g., [6,7]), species concentration in binary isothermal gas mixtures (e. g., [8,9]) or flow velocity (e. g., [10,11]). Furthermore simultaneous measurements of temperature and pressure [12,13] or temperature and flow velocity [14,15] have been performed successfully.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved measurement of the local equivalence ratio in a gaseous propane injection process using laser-induced gratings

et al. 2006

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Abstract:For the first time laser-induced gratings (LIGs) have been used for the investigation of a non-stationary pulse-repetitive injection process of gaseous propane, C 3 H 8 , into air. By recording and evaluating single-shot LIG signals it was possible to determine, on a cycle-averaged basis, the temporal evolution of the local (within a probe volume 300 μm in diameter and 10 mm in length) equivalence ratio and by this the fuel-air ratio. Two different data treatment strategies, subject to C 3 H 8 concentration range, were first tested at stationary conditions and then used to evaluate the LIG signals obtained during the injection process. The relative standard deviation of single-shot measurements were estimated to be 0.14 and 0.32 at 0.8 % and 10 % of propane concentration, respectively.

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Section: Introductionmentioning

confidence: 99%

Time-resolved measurement of the local equivalence ratio in a gaseous propane injection process using laser-induced gratings

et al. 2006

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“…Its frequency ω 3 may be shifted by ∆ω s = ω 0 − ω 3 with respect to the frequency of the probe beam, as e.g. done in [13]. The beam is adjusted to pass the LIG at the crossing point of the pump beams and to become superimposed to the diffracted probe beam.…”

Section: Electrostrictive and Thermal Lig Technique With Heterodyne Dmentioning

confidence: 99%

“…A strong interest to avoid seeding therefore exists. Several studies [3][4][5][6][7][8][9][10][11][12][13][14] in recent years have demonstrated the functionality of seedless diagnostics approaches in various flow regimes, employing electrostrictive and thermal laser-induced gratings (LIGs). The combination of LIGs with heterodyne detection [3] allows the simultaneous determination of flow velocity and temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Hart et al [11] determined flow velocities from heterodynedetected electrostrictive LIGs, comparing experimental data with modelling in the frequency as well as in the time domain. Hemmerling et al [13] applied the single-pulse heterodynedetected LIG technique to the investigation of the flow behind a rocket nozzle. Recirculation zones, predicted by numerical simulations, could be observed, using simplified signal analysis in the frequency domain (power spectrum).…”

Section: Introductionmentioning

confidence: 99%

“…We present in this paper the technique of electrostrictive LIGs for flow measurements, with heterodyne detection using a separate reference beam, and with data analysis in the frequency domain (power spectrum), as it had been applied in [13]. Properties and applicability of this technique, which allows for minimal and rapid signal post-processing, are described, and they are elucidated by simultaneous measurements of flow velocity and temperature in air jets behind a slot nozzle.…”

Section: Introductionmentioning

confidence: 99%

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Heterodyne-detected electrostrictive laser-induced gratings for gas-flow diagnostics

Neracher

Hubschmid

2004

Appl Phys B

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The signal of heterodyne-detected electrostrictive laser-induced gratings (LIGs) originates from the interference of a reference laser beam with the laser light diffracted at the counterpropagating sound-wave packets, which are generated in the overlap volume of crossed laser beams. The frequencies of the sound waves, which contain the information on the sound velocity and on the motion of the medium, can approximately be extracted from the frequencies at the maxima of the two peaks, which dominate the power spectrum of the heterodyne LIG signal intensity. In free-air jets behind a slot nozzle, flow velocities up to 60 m s −1 were determined by quick fits from the power spectrum and by fitting the time-dependent signal intensity data to model functions. Results agree well, the standard deviations being about one-half in the latter case (1.6-2.6 m s −1 , for positions close to the nozzle). Problems arising from the sampling and from the finite observation time of the signal intensity are discussed. Furthermore, the results of the LIG measurements were compared with data provided by laser Doppler anemometry. As an application of the instantaneous and unseeded LIG measurement technique, temperatures in heated air jets were determined simultaneously with the flow velocity by quick fits from the power spectrum.

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Local fuel concentration measurements for mixture formation diagnostics using diffraction by laser‐induced gratings in comparison to spontaneous Raman scattering

Kiefer¹,

Kozlov

Seeger³

et al. 2008

J Raman Spectroscopy

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The potential of the laser-induced gratings (LIGs) technique for the determination of fuel concentrations is investigated in comparison to the well-established spontaneous Raman scattering (SRS) technique. At pulse-repetitive excitation, the temporal shape of the LIG signals, containing non-resonant electrostrictive and resonant thermal contributions, as well as the Raman spectra were recorded in single-shot and accumulation modes. The measurements were performed in a laboratory system: in mixtures of propane as a fuel with nitrogen and air under stationary conditions in order to provide calibration data and to investigate the single-shot precision of measurements; and in the course of pulsed injection of gaseous propane into air at elevated pressures and temperatures. In the latter case, parameters of the experiment such as temperature, amount of injected gas and pressure were adjusted to be close to conditions of practical interest existing in real engines with direct injection (DI). The temporal variation of local propane concentration was tracked after the start of the injection pulse. Various approaches to the fast evaluation of the temporal shape of the measured LIG signals were tested, and their applicability in different ranges of propane concentrations, as well as single-shot measurement precision, were investigated. The results of employing the LIG technique were compared to those provided by the evaluation of the ratio of the integrated line intensities in the recorded SRS spectra.

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Rocket nozzle cold‐gas flow velocity measurements using laser‐induced gratings

Cited by 20 publications

References 6 publications

Time-resolved measurement of the local equivalence ratio in a gaseous propane injection process using laser-induced gratings

Time-resolved measurement of the local equivalence ratio in a gaseous propane injection process using laser-induced gratings

Heterodyne-detected electrostrictive laser-induced gratings for gas-flow diagnostics

Local fuel concentration measurements for mixture formation diagnostics using diffraction by laser‐induced gratings in comparison to spontaneous Raman scattering

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