Experimental study on the spray characteristics of a gas–liquid pintle injector element

Jin, Xuan; Shen, Chibing; Lin, Sen; Zhou, Rui

doi:10.1007/s12650-021-00815-6

Cited by 11 publications

(4 citation statements)

References 30 publications

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“…Their results show that increasing the gas/liquid momentum ratio and Weber number will help to reduce the spray angle and droplet diameter, respectively. Through mechanism studies on penetration depth, droplet diameter distribution, fragmentation and atomization characteristics of the near-orifice liquid jet under transverse gas film, some quantitative conclusions also have been drawn in our previous work [19,20]. The related studies inevitably involve the spray spatial distribution, and the spray angle and penetration depth are the common evaluation indicators.…”

Section: Introductionmentioning

confidence: 82%

“…Figure 4 shows the typical far-field spray structure of the pintle injector element taken at different perspectives [20]. The focal plane of the high-speed camera from the side view is the z = 0 plane shown in Figure 2b.…”

Section: Extraction Of the Windward Boundary Bandmentioning

confidence: 99%

“…The effect of the local momentum ratio Figure 6a visually reflects the distribution characteristics of the water jet/spray in the near-field region: the pure red part with a constant spray fraction of 1 was always occupied by the jet/spray; the pure blue part with a constant spray fraction of 0 was completely free of the jet/spray; the other part with a spray fraction between 0 and 1 was aroused by the spray windward boundary oscillation. It can be seen from Figure 6b that the extracted windward boundary band contained several spray fraction isolines, any of which can be regarded as the conventional spray windward trajectory [20]. The x-y plane in Figure 6c [20], i.e., the z = 0 plane shown in Figure 2b, is used for subsequent discussion.…”

Section: Effect Of Parameter On the Windward Boundary Bandmentioning

confidence: 99%

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Effect of Local Momentum Ratio on Spray Windward Distribution of a Gas–Liquid Pintle Injector Element

et al. 2022

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The variable-area pintle injector has unique geometry and spray characteristics compared to traditional coaxial injectors, and is advantageous for weight lightening and deep throttling of liquid rocket engines. To obtain an accurate prediction of the spray windward distribution of a gas–liquid pintle injector with discrete radial orifices, a pintle injector element using air and water as simulants was designed for spray experiments in the atmospheric environment. The air-film injection pressure drop and water-jet injection orifice diameter were both adjusted for a wide variance range from 0.19 to 2.85 for the local momentum ratio. Backlight imaging was adopted for shooting the frozen spray pattern from one side, and a new dimensionless parameter, i.e., the spray fraction, was defined to quantitatively analyze the time-averaged windward boundary band. The dimensionless spray windward boundary band model for a circular-orifice jet and the corresponding derivative formula of the spray half angle were summarized through parameter study. The predicted results of empirical models were in good agreement with the experimental results. It was found that when the local momentum ratio was about 1, the spray distribution range basically overlapped with the coverage scope of gas film with uniform liquid mist.

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Section: Introductionmentioning

confidence: 82%

Section: Extraction Of the Windward Boundary Bandmentioning

confidence: 99%

Section: Effect Of Parameter On the Windward Boundary Bandmentioning

confidence: 99%

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Effect of Local Momentum Ratio on Spray Windward Distribution of a Gas–Liquid Pintle Injector Element

et al. 2022

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“…Particularly, Heister held that pintle engines require a higher degree of integrated design of the pintle injector and the combustion chamber than other types of rocket engines [6]. Currently, most investigations are devoted to the atomization characteristics [7][8][9][10][11][12][13] and combustion performance of pintle injectors [14][15][16][17][18], so further investigations are required on the thermal protection and ablation-induced problems. Especially for cryogenic bipropellants such as liquid oxygen (LOX)/liquid hydrogen (LH2) and LOX/liquid methane (LCH4), the pintle tip ablation cannot be ignored.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Study on the Ablation Analysis of a Pintle Injector for GOX/GCH4 Rocket Engines

Chang

Zou

2023

Coatings

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In the present study, the ablation of a pintle injector on a 500N GOX/GCH4 rocket engine under different working conditions is studied experimentally and numerically. The temperature of the pintle tip and the combustion gas in the head zone was measured in a series of experiments by the thermocouples. Moreover, a three-dimensional model was established to simulate combustion and heat transfer concurrently and analyze the ablation state of the pintle injectors. The obtained results indicate that under a low chamber pressure (pc=0.25 MPa) and an increasing O/F ratio from 0.8 to 2, the tip temperature declines first, and then rises. At the designed working condition (pc=1.05 MPa and O/F = 3.2), the pintle tip suffered serious ablation, and the microstructure analysis indicates that the ablation failure of the stainless steel pintle tip originates from chromium precipitation. This phenomenon is especially more pronounced when the temperature exceeds 1273 K, which makes the structure fragile and vulnerable. This article helps to provide an understanding of the ablation failure of the pintle injectors, and the established model is capable of giving a prediction on the ablation status of the pintle tips consistent with the experiment.

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Prediction model of volume average diameter and analysis of atomization characteristics in electrostatic atomization minimum quantity lubrication

Jia

Liu

et al. 2023

Friction

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Minimum quantity lubrication (MQL) is a relatively efficient and clean alternative to flooding workpiece machining. Electrostatic atomization has the merits of small droplet diameter, high uniformity of droplet size, and strong coating, hence its superiority to pneumatic atomization. However, as the current research hotspot, the influence of jet parameters and electrical parameters on the average diameter of droplets is not clear. First, by observing the shape of the liquid film at the nozzle outlet, the influence law of air pressure and voltage on liquid film thickness (h) and transverse and longitudinal fluctuations are determined. Then, the mathematical model of charged droplet volume average diameter (VAD) is constructed based on three dimensions of the liquid film, namely its thickness, transverse wavelength (λh), and longitudinal wavelength (λz). The model results under different working conditions are obtained by numerical simulation. Comparisons of the model results with the experimental VAD of the droplet confirm the error of the mathematical model to be less than 10%. The droplet diameter distribution span value Rosin-Rammler distribution span (R.S) and percentage concentrations of PM10 (particle size of less than 10 µm)/PM2.5 (particle size of less than 2.5 µm) under different working conditions are further analyzed. The results show that electrostatic atomization not only reduces the diameter distribution span of atomized droplets but also significantly inhibits the formation of PM10 and PM2.5 fine-suspension droplets. When the air pressure is 0.3 MPa, and the voltage is 40 kV, the percentage concentrations of PM10 and PM2.5 can be reduced by 80.72% and 92.05%, respectively, compared with that under the pure pneumatic atomization condition at 0.3 MPa.

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Experimental study on the spray characteristics of a gas–liquid pintle injector element

Cited by 11 publications

References 30 publications

Effect of Local Momentum Ratio on Spray Windward Distribution of a Gas–Liquid Pintle Injector Element

Effect of Local Momentum Ratio on Spray Windward Distribution of a Gas–Liquid Pintle Injector Element

Experimental and Numerical Study on the Ablation Analysis of a Pintle Injector for GOX/GCH4 Rocket Engines

Prediction model of volume average diameter and analysis of atomization characteristics in electrostatic atomization minimum quantity lubrication

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