To understand the influence of pressure oscillation on the self-pulsation characteristics of the gas-liquid swirl coaxial injector, non-reactive spray experiments are conducted with water and air at atmospheric pressure. The spray morphology of the pressure swirl injector with and without pressure oscillation is investigated, and that of the gas-liquid swirl coaxial injector with and without the pressure oscillation when self-pulsation occurs is also investigated. The results indicate that the conical liquid film produced by the pressure swirl injector oscillates periodically with the pressure oscillation in the supply system, and the Klystron effect occurs simultaneously. The frequency of the conical liquid film oscillation and the Klystron effect occurrence is consistent with that of pressure oscillation in the supply system. The Klystron effect decreases the spray cone angle, and wrinkles the conical liquid film. The self-pulsated spray morphology of the gas-liquid swirl coaxial injector is also significantly influenced by the pressure oscillation in the supply system. The decrease of the spray cone angle caused by the Klystron effect increases the branches of the Christmas tree and the frequency of self-pulsation. This is because the Klystron effect occurs when the faster liquid film overtake the slower liquid film, which increases the velocity of the liquid film. And the larger the liquid film velocity, the larger the self-pulsation frequency. Although frequency locking does not occur with pressure oscillation, the strength of self-pulsation is decreased to some extent, and one dominant self-pulsation frequency evolves into two domain frequencies.
[1] IM J H, KIM D, YOON Y, et al. Self-pulsation characteristics of a swirl coaxial injector with various injection and geometric conditions:AIAA-2005-3749[R]. Reston, VA:AIAA, 2005.
[2] BAZAROV V G, YANG V. Liquid-propellant rocket engine injector dynamics[J]. Journal of Propulsion and Power, 1998, 14(5):797-806.
[3] NUNOME Y, TAMURA H, ONODERA T, et al. Effect of liquid disintegration on flow instability in a recessed region of a shear coaxial injector:AIAA-2009-5389[R]. Reston, VA:AIAA, 2009.
[4] IM J H, YOON Y. The effects of the ambient pressure on self-pulsation characteristics of a gas/liquid swirl coaxial injector:AIAA-2008-4850[R]. Reston, VA:AIAA, 2008.
[5] SIVAKUMAR D, KULKARNI V. Regimes of spray formation in gas-centered swirl coaxial atomizers[J]. Experimental Fluids, 2011, 51(3):587-596.
[6] IM J H, KIM D, HAN P, et al. Self-pulsation characteristics of a gas-liquid swirl coaxial injector[J]. Atomization and Sprays, 2009, 19(1):57-74.
[7] SASAKI M, SAKAMOTO H, TAKAHASHI M, et al. Comparative study of recessed and non-recessed swirl coaxial injectors:AIAA-1997-2907[R]. Reston, VA:AIAA, 1997.
[8] BAZAROV V G. Self-pulsations in coaxial injectors with central swirl liquid stage:AIAA-1995-2358[R]. Reston, VA:AIAA, 1995.
[9] BAZAROV V G. Non-linear interactions in liquid-propellant rocket engine injectors:AIAA-1998-4039[R]. Reston, VA:AIAA, 1998.
[10] YANG L J, GE M H, ZHANG M Z, et al. Spray characteristics of recessed gas-liquid coaxial swirl injector[J]. Journal of Propulsion and Power, 2008, 24(6):1332-1339.
[11] 康忠涛, 张新桥, 成鹏, 等. 气核尺寸对气液同轴离心式喷嘴自激振荡的影响[J]. 航空学报, 2014, 35(12):3283-3292. KANG Z T, ZHANG X Q, CHENG P, et al. Influence of gas core dimension on self-pulsation of gas-liquid swirl coaxial injector[J]. Acta Aeronautica et Astronautica Sinica, 2014, 35(12):3283-3292(in Chinese).
[12] FU Q F, YANG L J. Theoretical investigation on the dynamics of a gas-liquid coaxial swirl injector[J]. Journal of Propulsion and Power, 2011, 27(1):144-150.
[13] HUANG Y, ZHOU J, HU X, et al. Acoustic model for the self-oscillation of coaxial swirl injector:AIAA-1997-3328[R]. Reston, VA:AIAA, 1997.
[14] EBERHART C J, LINEBERRY D M, FREDERICK R A. Detailing the stability boundary of self-pulsations for a swirl-coaxial injector element:AIAA-2013-4064[R]. Reston, VA:AIAA, 2013.
[15] LI Q, KANG Z, ZHANG X, et al. Effect of recess length on the spray characteristics of liquid-centered swirl coaxial injectors[J]. Atomization and Sprays, 2016, 26(6):535-550.
[16] KANG Z T, LI Q L, CHENG P, et al. Effects of recess on the self-pulsation characteristics of liquid-centered swirl coaxial injectors[J]. Journal of Propulsion and Power, 2016, 32(5):1124-1132.
[17] IM J H, SEONGHO C, YOON Y, et al. Comparative study of spray characteristics of gas-centered and liquid-centered swirl coaxial injectors[J]. Journal of Propulsion and Power, 2010, 26(6):1196-1204.
[18] KANG Z T, LI Q L, CHENG P, et al. Effects of self-pulsation on the spray characteristics of gas-liquid swirl coaxial injector[J]. Acta Astronautica, 2016, 127(1):249-259.
[19] LIEUWEN T C. Unsteady combustor physics[M]. Cambridge:Cambridge University Press, 2012:90-93.
[20] RICHECOEUR F. Experimentations and simulations numeric on interaction modes acoustic transve at flames cryotechniques[D]. Paris:Ecole Centrale Paris, 2006:68-95.
[21] RICHECOEUR F, DUCRUIX S, SCOUFLAIRE P, et al. Experimental investigation of high-frequency combustion instabilities in liquid rocket engine[J]. Acta Astronautica, 2008, 62(1):18-27.
[22] RICHECOEUR F, DUCRUIX S, SCOUFLAIRE P, et al. Effect of temperature fluctuations on high frequency acoustic coupling[J]. Proceedings of the Combustion Institute, 2009, 32(2):1663-1670.
[23] RICHECOEUR F, SCOUFLAIRE P, DUCRUIX S, et al. Interactions between propellant jets and acoustic modes in liquid rocket engines:Experiments and simulations:AIAA-2006-4397[R]. Reston, VA:AIAA, 2006.
[24] HARDI J S, SCOTT B, MICHAEL O, et al. Coupling behaviour of LOx/H2 flames to longitudinal and transverse acoustic instabilities:AIAA-2012-4087[R]. Reston, VA:AIAA, 2012.
[25] HARDI J S, MARTINEZ H C G, OSCHWALD M, et al. LOx jet atomization under transverse acoustic oscillations[J]. Journal of Propulsion and Power, 2014, 30(2):337-349.
[26] MÉRY Y, HAKIM L, SCOUFLAIRE P, et al. Experimental investigation of cryogenic flame dynamics under transverse acoustic modulations[J]. Comptes Rendus Mecanique, 2013, 341(1-2):100-109.
[27] YI T, SANTAVICCA D A. Forced flame response of turbulent liquid-fueled lean-direct-injection combustion to fuel modulations[J]. Journal of Propulsion and Power, 2009, 25(6):1259-1271.
[28] LIU J, ZHANG X Q, LI Q L, et al. Effect of geometric parameters on the spray cone angle in the pressure swirl injector[J]. Proceedings of the Institution of Mechanical Engineers, Part G:Journal of Aerospace Engineering, 2013, 227(2):342-353.
[29] CHENG P, KANG Z, CHEN H, et al. Influence of pressure oscillation induced klystron effect on the inner flow and spray characteristics of pressure swirl injector[C]//Proceedings of the 18th Annual Conference on Liquid Atomization and Spray Systems-Asia, 2016:1-8.
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