Effect of Momentum Ratio on the Mixing Performance of Unlike Split Triplet Injectors

Won, Y. D.; Cho, Y. H.; Lee, S. W.; Yoon, Woong

doi:10.2514/2.6008

Cited by 21 publications

(6 citation statements)

References 4 publications

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“…This fact also indicates that cold-flow tests are effective approaches for predicting the performance of actual thrusters lately confirmed by several studies. [4][5][6][7][8] However, the physical meaning of the correlations has been rarely discussed so far.…”

Section: Introductionmentioning

confidence: 99%

Unified Length Scale of Spray Structure by Unlike Impinging Jets

Inoue

Takeuchi

Nozaki

et al. 2019

Trans. Japan Soc. Aero. S Sci.

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In bi-propellant thrusters, impinging type injectors are widely used to deliver propellants to a combustion chamber. By impinging the jet streams of fuel and oxidizer, the spray spreads while the two liquids mix. To design the injectors, several correlations related to injection conditions have been proposed (e.g., Rupe factor), and practically utilized over the last half-century. However, the physical meanings of the past correlations are not well understood, because the essential scale of the spray structure is elusive. In this paper, we derive the global length scale of the spray produced by impinging injectors of unlike doublet, fuel-oxidizer-fuel triplet, and oxidizer-fuel-oxidizer triplet in a consistent manner. The unified length scale is found representing the spray width ratio of oxidizer to fuel evidenced by comprehensive cold-flow tests including several past studies, covering various parameters such as injector types, nozzle diameters, physical properties of working liquids, and injection velocities. Finally, we clearly provide the physical meaning based on practical correlations in a phenomenological sense.

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Section: Introductionmentioning

confidence: 99%

Unified Length Scale of Spray Structure by Unlike Impinging Jets

Inoue

Takeuchi

Nozaki

et al. 2019

Trans. Japan Soc. Aero. S Sci.

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“…4,6 Because the large difference between the oxidizer and fuel hole diameters may reduce the atomization efficiency, a fueloxidizer-oxidizer-fuel (F-O-O-F) (or unlike-split-triplet) injector, which separates the single oxidizer hole of the F-O-F injector into double oxidizer holes, was designed. 6,7 Pavli 6 reported from his subscale engine tests that the combustion performance of the F-O-O-F injector is as high as that of the O-F-O injector, whereas that of a pair of like-doublet [fuel-fuel (F-F) and oxidizer-oxidizer (O-O)] injectors is relatively low. Although the hot test definitely showed the high combustion performance of the F-O-O-F injector, it was difficult to find the fundamental reasons for this high performance because the atomization or mixing mechanism of liquid propellants could not be investigated under combustion conditions.…”

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confidence: 99%

“…As a measurement technique for the mass distribution, a mechanical patternator, which collects the injected spray mass at many cells during a specified time, is used. 7,8 However, this method has several limitations: low spatial resolution, measurement inconvenience, disturbance to the spray, and so on. As a nonintrusive optical patternator, a phase Doppler particle analyzer, (PDPA), which measures both the sizes and velocities of spherical drops using light scattering interferometry, can obtain very reliable mass flux data.…”

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confidence: 99%

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Comparison of Mixing Characteristics of Unlike Triplet Injectors Using Optical Patternator

Jung

Lim

Yoon

et al. 2005

Journal of Propulsion and Power

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Mixing characteristics of an unlike split triplet fuel-oxidizer-oxidizer-fuel (F-O-O-F) injector, which separates the single oxidizer hole of an unlike triplet fuel-oxidizer-fuel (F-O-F) injector for liquid-rocket engines, were investigated under cold-flow conditions. The spray mass distributions of the fuel and oxidizer were measured using an optical patternator based on the planar liquid laser-induced fluorescence technique, and the mixing mechanism and the mixing efficiency of the F-O-O-F injector were compared with those of the F-O-F injector. Results showed that the mixing efficiency of the F-O-O-F injector is less sensitive to the changes of the momentum ratio or impingement angle than that of the F-O-F injector because the mixing of the F-O-O-F injector is determined by the coalescing process of two liquid sheets, whose impinging momentum is weak. Therefore, the F-O-O-F injector has an advantage in starting injection wherein the momentum ratio is usually different from the operating condition. Nomenclature DI = index of deviation from injection mass flow rate d = orifice diameter E m = mixing efficiency, % G = gray level of fluorescence signal I i = averaged intensity of incident laser beam K = constanṫ M = total mass flow rate injected from orifice hole(s) or fuel holeṡ m = mass flow rate of spray passing local cell n = number of pixels where r ≤ R n = number of pixels where r > R R = total mixure fraction of fuel and oxidizer,Ṁ o /(Ṁ o +Ṁ f ) R M = momentum ratio of oxidizer to fuel,Ṁ o V o /Ṁ f V f r = local mixture fraction of fuel and oxidizer,ṁ o /(ṁ o +ṁ f ) V = injection velocitȳ V d = averaged radial velocity of drops V z = z-axial component of spray velocity Z 1 = distance from injector surface to measurement location Z 2 = distance from last impingement point to measurement location θ = one-half impingement angle, angle between fuel and oxidizer orifices µ = dynamic viscosity ρ = liquid densitȳ ρ = time-averaged spray density σ = surface tension Subscripts f = fuel o = oxidizer

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“…The gel separates within hours but is always mixed before being loaded into the hydraulic cylinders which restores its homogeneity. The physical properties of the gel are a density of 866.9 kg/m 3 (1.68 slugs/ft3 ), a surface tension of 0.0255 N/m (0.00175 lb f /ft) and a viscosity versus shear rate curve, measured from the rheometer, is shown in figure 15. The gelled simulant is dyed at slightly different concentrations than the non-gelled simulant.…”

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confidence: 99%

Mixing Analysis of Like Doublet Injectors in High Pressure Environments for Gelled Propellant Simulants

Notaro

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Impinging doublet injectors offer rocket designers an effective way to atomize and mix opposing jets of fuel and oxidizer. The adaptability of the injector designs and ease of manufacturing make them attractive choices for designers. The adaptability of injector designs introduces many variables to the system like orifice diameter, nozzle orifice pairings, and working fluid to name a few. This expanse of variables requires This work would not have been possible without the support from United States Army Research Office under the Multi-University Research Initiative. I would like to thank Dr. Jong Guen Lee for allowing me this graduate opportunity and for his academic support through my undergraduate studies and my graduate research. I would also like to thank my committee members of Dr. San-Mou Jeng and Dr. Milind Jog. I appreciate them taking time and effort to apply their expertise to critiquing my work. There are a few students and a staff member I would like to thank for their help with experimentation. The student members are Chandra Ramasubramanian, Charlie Hinton, Jake Keller, Vaughn Bostwick, Andrew Stubblebine, Wessam Estefanos and Jun Hee Han. They were invaluable help during setup and testing. The staff member is Curt Fox who without his help, I would have been able to work as efficiently and as safely. Lastly, I want to thank my friends and family for their support throughout my academic journey.

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Effect of Momentum Ratio on the Mixing Performance of Unlike Split Triplet Injectors

Cited by 21 publications

References 4 publications

Unified Length Scale of Spray Structure by Unlike Impinging Jets

Unified Length Scale of Spray Structure by Unlike Impinging Jets

Comparison of Mixing Characteristics of Unlike Triplet Injectors Using Optical Patternator

Mixing Analysis of Like Doublet Injectors in High Pressure Environments for Gelled Propellant Simulants

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