To reveal the characteristics of unstable propagation of the rotating detonation wave in the plane-radial structure, a two-dimensional numerical simulation of the structure was conducted with 2H2+O2+3.76N2 being the reaction mixture. The flow field structure under the unstable propagation mode was analyzed, as well as variation of detonation parameters, flow parameters and the pressure amplification ratio at the exit. Results indicate that decoupling and re-initiation of the rotating detonation wave occur repeatedly under the unstable propagation mode. The diffraction of the inner circle geometry weakens the intensity of the detonation wave. The detonation wave decouples first near the exit, and then the decoupling region expands to the interior flow field gradually. The collision of the reflected wave and the leading shock wave urges the formation of the hot spot in the flow field, initiating the detonation wave again. The detonation pressure, temperature and propagating velocity vary with the "decoupling and re-initiation" process of the detonation wave. The unstable propagation of the rotating detonation wave has only a small effect on the velocity components and Mach number in the exit, but a significant effect on the exit pressure amplification ratio. The pressure amplification ratio varies periodically with time, and the amplitude is high and unsteady. The cycle period of the pressure amplifying ratio is consistent with the period of "decoupling and re-initiation" process, and the cycle frequency is about 21.6 kHz after dynamic stability.
[1] VOITSEKHOVSKⅡ B V, MITROFANOV V V, TOPCHIYAN M E. Structure of the detonation front in gases[J]. Combustion, Explosion, and Shock Waves, 1969, 5(3):385-395(in Russian).[2] BYKOVSKⅡ F A, ZHDAN S A, VEDERNIKOV E F. Continuous spin detonations[J]. Journal of Propulsion and Power, 2006, 22(6):1204-1216.[3] BYKOVSKⅡ F A, ZHDAN S A, VEDERNIKOV E F. Continuous detonation of syngas-air mixtures in an annular flow-type cylindrical combustor[C]//24th International Colloquium on the Dynamics of Explosions and Reactive Systems, 2013:1-4.[4] ANAND V, GEORGE A S, DRISCOLL R, et al. Characterization of instabilities in a rotating detonation combustor[J]. International Journal of Hydrogen Energy, 2015, 40(46):16649-16659.[5] ANAND V, GEORGE A S, DRISCOLL R, et al. Longitudinal pulsed detonation instability in a rotating detonation combustor[J]. Experimental Thermal and Fluid Science, 2016, 77:212-225.[6] RANKIN B A, RICHARDSON D R, CASWELL A W, et al. Chemiluminescence imaging of an optically accessible non-premixed rotating detonation engine[J]. Combustion and Flame, 2017, 176(1):12-22.[7] ZHANG H L, LIU W D, LIU S J. Experimental investigations on H2/air rotating detonation wave in the hollow chamber with Laval nozzle[J]. International Journal of Hydrogen Energy, 2017, 42(5):3363-3370.[8] 刘世杰, 林志勇, 孙明波, 等. 旋转爆震波发动机二维数值模拟[J]. 推进技术, 2010, 31(5):634-640. LIU S J, LIN Z Y, SUN M B, et al. Two-dimensional numerical simulation of rotating detonation wave engine[J]. Journal of Propulsion Technology, 2010, 31(5):634-640(in Chinese).[9] 刘世杰, 覃慧, 林志勇, 等. 连续旋转爆震波细致结构及自持机理[J]. 推进技术, 2011, 32(3):431-436. LIU S J, QIN H, LIN Z Y, et al. Detailed structure and propagating mechanism research on continuous rotating detonation wave[J]. Journal of Propulsion Technology, 2011, 32(3):431-436(in Chinese).[10] MANABU H, FUJIWARA T, PIOTR W. Fundamentals of rotating detonations[J]. Shock Waves, 2009, 19(1):1-10.[11] EUDE Y, DAVIDENKO D M, GÖKALP I, et al. Use of the adaptive mesh refinement for 3D simulations of a CDWRE (Continuous Detonation Wave Rocket Engine):AIAA-2011-2236[R]. Reston, VA:AIAA, 2011.[12] FROLOV S M, DUBROVSKⅡ A V, IVANOV V S. Three-dimensional numerical simulation of the operation of a rotating-detonation chamber with separate supply of fuel and oxidizer[J]. Russian Journal of Physical Chemistry B, 2013, 7(1):35-43.[13] TANG X M, WANG J P, SHAO Y T. Three-dimensional numerical investigations of the rotating detonation engine with a hollow combustor[J]. Combustion and Flame, 2015, 162(4):997-1008.[14] LI J, NING J G, ZHAO H, et al. Numerical investigation on the propagation mechanism of steady cellular detonations in curved channels[J]. Chinese Physics Letters, 2015, 32(4):144-147.[15] BYKOVSKⅡ F A, ZHDAN S A, VEDERNIKOV E F, et al. Detonation of a coal-air mixture with addition of hydrogen in plane-radial vortex chambers[J]. Combustion, Explosion, and Shock Waves, 2011, 47(4):473-482.[16] NAKAGAMI S, MATSUOKA K, KASAHARA J, et al. Visualization of rotating detonation waves in a plane combustor with a cylindrical wall injector:AIAA-2015-0878[R]. Reston, VA:AIAA, 2015.[17] ISHIYAMA C, MIYAZAKI K, NAKAGAMI S, et al. Experimental study of research of centrifugal-compressor-radial-turbine type rotating detonation engine:AIAA-2016-5103[R]. Reston, VA:AIAA, 2016.[18] HIGASHI J, ISHIYAMA C, NAKAGAMI S, et al. Experimental study of disk-shaped rotating detonation turbine engine:AIAA-2017-1286[R]. Reston, VA:AIAA, 2017.[19] 卓长飞, 武晓松, 封锋. 底部排气弹三维湍流燃烧的数值模拟[J].固体火箭技术, 2013, 36(6):720-726. ZHUO C F, WU X S, FENG F. Numerical simulation of three-dimensional turbulent combustion of the base bleed projectile[J]. Journal of Solid Rocket Technology, 2013, 36(6):720-726(in Chinese).[20] 卓长飞, 武晓松, 封峰. 超声速流动中底部排气减阻的数值研究[J].兵工学报, 2014, 35(1):18-26. ZHUO C F, WU X S, FENG F. Numerical research on drag reduction of base bleed in supersonic flow[J]. Acta Armamentarii, 2014, 35(1):18-26(in Chinese).[21] 马虎, 武晓松, 王栋, 等. 旋转爆震发动机数值研究[J]. 推进技术, 2012, 33(5):820-825. MA H, WU X S, WANG D, et al. Numerical investigation for rotating detonation engine[J]. Journal of Propulsion Technology, 2012, 33(5):820-825(in Chinese).[22] 夏镇娟, 武晓松, 马虎, 等. 圆盘结构下旋转爆震波的二维数值研究[J]. 推进技术, 2017, 38(6):1409-1418. XIA Z J, WU X S, MA H, et al. Two-dimensional numerical simulation of rotating detonation wave in plane-radial structure[J]. Journal of Propulsion Technology, 2017, 38(6):1409-1418(in Chinese).
CJA