The break phenomenon of self-pulsation for liquid-centered swirl coaxial injectors

Bai, Xueyan; Cao, Pengjin; Li, Qinglian; Cheng, Peng

doi:10.1016/j.ijmultiphaseflow.2021.103708

Cited by 5 publications

(4 citation statements)

References 24 publications

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“…The dominant frequency of pressure oscillation when selfpulsation occurs can be controlled to a high or low level by adjusting the LOX/GH 2 mixing ratio. This may prevent the pressure oscillation frequency coupling with the acoustic oscillation frequency in the combustion chamber (4) The initial temperature of GH 2 rarely influences the flow and atomization characteristics (e.g., the liquid sheet thickness, the distribution of liquid filaments) while it would change the dominant frequency and corresponding pressure apparently during the selfpulsation. The pressures of low-frequency and high-frequency increase with the increase of the temperature.…”

Section: Data Availabilitymentioning

confidence: 99%

“…However, due to the collision between the gas and liquid sheet being too violent in the recess chamber of the injector, it may cause the pressure and flow rate constantly varying at the injector outlet. This is reflected in the periodic oscillation of the liquid phase in the spray field, which is called self-pulsation phenomenon [4][5][6]. Self-pulsation oscillation could greatly affect the propellant atomization process and would cause a strong whistling sound at the injector outlet.…”

Section: Introductionmentioning

confidence: 99%

“…When the injector is sensitive to changes in some fluid parameters near the outlet, it is likely to produce self-pulsation oscillations due to the hydraulic instability. However, Bai et al [4] suggested that the self-pulsation is caused by the periodic blocking effect of the conical liquid sheet, resulting in periodic pressure oscillation inside the recess chamber. The pressure reacts to the liquid sheet and then causes it to oscillate.…”

Section: Introductionmentioning

confidence: 99%

“…The gas-liquid phase interaction is enhanced, and the intensity of self-excited oscillations is increased. By numerical simulation and some experiments at ambient temperature for LCSC injector, Bai et al [4] found that if the annular slit width becomes larger when the gas-liquid ratio is very small, then the self-pulsation will become weaker. If the annular slit width becomes larger again when the gasliquid ratio is not that small, the self-pulsation will not become weaker as described earlier.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Study on the Self-Pulsation Characteristics of LOX/GH2 Swirl Coaxial Injector

Qiao,

Liang,

Liu

et al. 2024

International Journal of Aerospace Engineering

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To investigate the self-pulsation characteristics of a liquid-centered swirl coaxial injector with liquid oxygen (LOX) and gas hydrogen (GH2) as the working mediums under supercritical condition, a numerical simulation was employed. The transient simulation of the flow and injection process of cryogenic propellant was carried out using the RNG k−ε turbulence model, VOF model, and Peng-Robinson equation of state. The frequency spectrum of calculated pressure oscillation agreed with the experimental data. The amplitude-frequency characteristics of recess region, LOX, and GH2 paths when self-pulsation occurs were analyzed. The effects of operating parameters, such as the flow rate of LOX or GH2 and the initial GH2 temperature, on the self-pulsation, were evaluated specifically. Results reveal that the self-pulsation results from the periodic variation of pressure and velocity caused by the periodic blocking of annular gas by the liquid sheet. The dominant frequencies of pressure oscillation in the recess region, upstream of LOX, or GH2 path are diverse. But for the points in each region, the dominant frequency is about the same. When the LOX/GH2 mixing ratio increases, the liquid sheet thickness and the number of liquid filaments increase. The position where filaments are massively broken into droplets moves further downstream. For the same mixing ratio, the flow rate of LOX has a greater impact on the atomization features. The pressures corresponding to low or high frequency increase when the initial GH2 temperature raises. The higher temperature would shift the dominant oscillation between the low and high regimes.

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Section: Data Availabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Study on the Self-Pulsation Characteristics of LOX/GH2 Swirl Coaxial Injector

Qiao,

Liang,

Liu

et al. 2024

International Journal of Aerospace Engineering

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Spray characteristics of gel fuel in a gas-centered coaxial swirl injector with variable recess ratios

Liu

Zhang

2022

Fuel

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Experimental and numerical investigation of spray characteristics of gas–liquid swirl coaxial injectors

Cao,

Cui,

Bai

et al. 2024

Physics of Fluids

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To investigate the velocity distribution and atomization characteristics of gas–liquid swirl coaxial (GLSC) injectors, atomization experiments and simulations were conducted under atmospheric conditions. The velocity distribution and morphology of the spray from GLSC injectors at varying gas–liquid ratios were measured using particle image velocimetry. The gas–liquid interaction, breakup dynamics, and the velocity of liquid sheet were simulated based on the three-dimensional volume of fluid to discrete particle model (VOF-to-DPM) and octree adaptive mesh refinement. Additionally, a method for extracting droplet diameters from high-quality images has been developed and validated. The results indicate that the sprays maintain a stable cone when the gas–liquid ratio is low. As the gas–liquid ratio increases, particularly at larger recess ratios, self-pulsation phenomena occur. During self-pulsation, the spray cone angle is enlarged, and the breakup length shortens. In a stable spray field, the center exhibits a low velocity region (5–10 m/s), while the spray periphery shows a high velocity region (20–25 m/s). Self-pulsation is induced by the “Klystron effect,” which arises from the Kelvin–Helmholtz (K–H) instability at the gas–liquid interface. The center of the self-pulsated spray transitions to a high velocity region due to the accelerated droplet motion driven by the annular gas flow through the spray's center. The radial distribution of mean droplet diameters for both stable and self-pulsated sprays has been summarized. As the gas–liquid ratios and recess ratios increase, the global droplet diameters gradually decrease, with a 75% of droplet diameters falling between 0 and 0.1 mm.

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The break phenomenon of self-pulsation for liquid-centered swirl coaxial injectors

Cited by 5 publications

References 24 publications

Numerical Study on the Self-Pulsation Characteristics of LOX/GH2 Swirl Coaxial Injector

Numerical Study on the Self-Pulsation Characteristics of LOX/GH2 Swirl Coaxial Injector

Spray characteristics of gel fuel in a gas-centered coaxial swirl injector with variable recess ratios

Experimental and numerical investigation of spray characteristics of gas–liquid swirl coaxial injectors

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