关键词: 旋转爆震, 填充不均匀, 侧向膨胀, 爆震波, 传播特性

Abstract: Numerical study was carried out to investigate the impact of the non-uniform filling of the fresh mixture on the detonation wave propagating in the disk-shape and hollow rotating detonation combustor. The propagation characteristics in the two-dimensional curved channel with lateral expansion on the inner side were analyzed by fixing the virtual inner wall radius (rin) at 65 mm and radial height (hr) at 15 mm while varying the incomplete filling distance (i), initial pressure (p0), dilution ratio (β) and temperature of combustion products (Tp).. Considering the coupled effects of axial and radial expansions, simula-tions were also conducted in the three-dimensional channel by varying the axial filling height of the fresh mixture (ha). In the two-dimensional channel where only the lateral expansion effect exists, four propagating modes were observed, i.e., a stable mode, a weakly unstable mode, a strongly unstable mode, and a deflagration mode based on the velocity deficit and whether the detonation wave degenerates into a deflagration wave. Critical criteria for mode transitions have been established in terms of the incomplete filling distance and the average cell size (λa), when i＜hr-3.5λa, the stable mode is available; when hr-3.5λa＜i＜hr -2.5λa, the weakly unstable mode emerges; when hr -2.5λa＜i＜hr -1.6λa, the highly unstable mode can be obtained; and when i＞hr -1.6λa, the detonation completely decouples and transits into the deflagration mode. The increase in the tem-perature of combustion products also leads to more stable detonation propagation. In the three-dimensional condition where the detonation wave undergoes the radial and axial expansion simultaneously, a linear decay coefficient of the maximum pressure (κ0.7) was defined to quantify the sensitivity of the detonation wave to pressure loss in the axial direction. As the axial filling height increases or the radial position approaches the outer wall, κ0.7 exhibits a decreasing trend, indicating an increased resistance to the inward development of pressure loss and an enhanced ability of the detonation wave to endure lateral expansion.

Key words: Rotating detonation, Non-uniform filling, Lateral expansion, Detonation wave, Propagation characteristics