Chikishev L.M.   Lobasov A.   Sharaborin D.   Gobyzov O.A.   Dulin V.   Bilsky A.   Tsatiashvili V.V.   Avgustinovich V.G.   Markovich D.M.  

PIV/PLIF measurements in advanced premixing GT-burner

Reporter: Chikishev L.M.

Chikishev L.M.1,2, Lobasov A.S. 1,2, Sharaborin D.K. 1,2, Gobyzov O.A. 1,2, Dulin V.M. 1,2, Bilsky A.V. 1,2, Tsatiashvili V.V. 3, Avgustinovich V.G. 3, Markovich D.M. 1,2

1Kutateladze Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences, 630090, Novosibirsk, Russia
2Novosibirsk State University 630090, Novosibirsk, Russia
3JSC Aviadvigatel 614010, Perm, Russia

Mixing processes play one of the key roles in combustion stabilization and pollutant formation. The present work is aimed at flow structure and mixing study in non-reacting flow of an advanced premixing GT-burner. Due to complex character of the flow in real industrial devices it is necessary to make a validation of CFD simulation results. Such validation demands comprehensive experimental data. It is known that acetone planar laser-induced fluorescence (PLIF) at isobaric, isothermal and non-reacting conditions allows quantitative measurement of the mixing [1]. For example Su and Mungal investigated turbulent quantities of mixing in crossflowing jets using PIV/PLIF technique [2] in laboratory-scale condition. But this technique is quite robust to provide instantaneous measurements in real-scale experimental setups at real-istic flow-rates.

In this work simultaneous PIV/PLIF measurements were carried out for a cold flow GT-burner at realistic flow-rates conditions (up to 0.5 kg/s air flow and elevated pressure). The burner was developed in JSC Aviadvigatel. The nozzle diameter was 80 mm and the cylindrical combustion chamber diameter was 120 mm. The Reynolds number was 300 000 based on the mean flow rate and nozzle diameter. The measurement area size was 50x120 mm. For safety reasons the real fuel (natural gas) was replaced with neon gas to simulate stratification in a strongly swirling flow. PIV system with double-pulsed Nd:YAG laser (Quantel EverGreen 200) and ImperX IGV-B2020 (4Mpix) camera was used. To provide PLIF measurements, the fourth harmonic of pulsed Nd:YAG laser (Quantel Brilliant B) at 266 nm (70 mJ per pulse) was used to excite acetone vapor fluorescence. The fluorescence signal was captured using ICCD camera (PI-MAX4, Princeton Instruments) equipped with a set of optical filters. The two systems were synchronized using Berkeley Nucleonics BNC 575 TTL pulse generator. Spatial overlapping of PIV and PLIF measurement areas were provided by using two light-sheet forming optics (the collimated one for quantitative PLIF measurements and divergent one for PIV). An image pre-processing was performed to reduce an artificial “stripes” introduced by inhomogeneous lighting. Turbulent flux measurements require PIV and PLIF systems to be well aligned in space and time. A calibration target was placed into the measurement area be-forehand in order to align the PIV and PLIF fields of view.

Acetone was seeded into the flow by bubbling through thermally stabilized acetone bath to provide quantitative fuel concentration measurements. To provide velocity measurements, the flow was seeded with water-glycerol mixture particles. After several minutes of operation the walls of quarts-glass cylinder became non-transparent due to thin film contamination. It was a challenge to make accurate measurements due to reflections, absorption and compromise between transparence of the combustion chamber walls and the required seeding density. Fig. 1 demonstrates the results of the instantaneous measurements of the passive tracer concentration and velocity field. As could be seen, acetone concentration is well correlated with the flow: high gradient region of the passive tracers corresponds to the swirling flow mixing layer region. Downstream 0.5 nozzle diameter the concentration field became almost uniform.

In the final analysis it was corroborated that planar optical techniques are capable of re-trieving information that is crucial for the verification of the numerical models and cannot be recovered by single-point probes. The quality of the experimental data and image processing algorithms allowed to measure correlations of the velocity and passive tracer concentration fields. Distributions of turbulent transport characteristics were recovered from the experimental data. This result was employed to verify CFD code, used to predict the velocity and concentra-tion distribution in this GT-burner configuration.

1. Lozano, A., Smith, S. H., Mungal, M. G., and Hanson, R. K. Concentration measurements in a trans-verse jet by planar laser-induced fluorescence of acetone // AIAA J. 1993, Vol. 32, P. 218-221.
2. Su L.K., Mungal M.G. Mixing in cross-flowing jets: Turbulent quantities // 43rd Aerospace Science Meeting and Exhibit 10-13 January, Reno, Nevada, AIAA 2005-305

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