Comparative Study of Spray Characteristics of Gas-Centered and Liquid-Centered Swirl Coaxial Injectors

Im, Jaehyun; Cho, Seongho; Yoon, Youngbin; Moon, Insang

doi:10.2514/1.48436

Cited by 57 publications

(26 citation statements)

References 10 publications

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“…2. The pressure swirl injector has the same configuration as the injector of Liu et al [19], which adopts four tangential entries, located every 90 deg, to form a swirl motion of the liquid. A conical liquid sheet at the injector exit and a gas core in the injector are produced with the centrifugal effect.…”

Section: A Experimental Facilitiesmentioning

confidence: 99%

Effects of Recess on the Self-Pulsation Characteristics of Liquid-Centered Swirl Coaxial Injectors

Kang

Cheng

et al. 2016

Journal of Propulsion and Power

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The self-pulsation characteristics of liquid-centered swirl coaxial injectors have been investigated using a Photron Fastcam SA-1.1 camera and a PULSE system (B&K Corp., 3650 type). The effects of both recess length and injection condition were analyzed and discussed. The flow pattern in the recess chamber of a liquid-centered swirl coaxial injector can be classified into three types, namely, outer, critical, and inner mixing flow. Once the critical flow approaches, self-pulsation is about to occur. When self-pulsation occurs, the spray oscillates with a Christmas tree shape. The Christmas-tree-like spray periodically produces droplet clusters, making horizontal spray width and mass flux oscillate periodically. Self-pulsation is the strongest when the flow is around the critical mixing flow. Both variations of recess length and injection condition can change the flow pattern in the recess chamber. When the flow pattern moves away from the critical mixing flow, self-pulsation is suppressed. All the frequency behaviors of selfpulsation indicate that self-pulsation is strongly related to Kelvin-Helmholtz instability. A possible mechanism of selfpulsation is also presented. This mechanism interprets the experiments of the present study and the results of literature well. Nomenclature D = diameter or distance, m h = film thickness, m k = specific heat ratio L = length, m _ m = mass flow rate, kg∕s P = pressure, Pa R = swirling radius or gas constant T = temperature, K u = axial velocity, m∕s w = circumferential velocity, m∕s α = spray angle, deg Δ = difference θ = convergent angle of the pressure swirl injector, deg μ = dynamic viscosity, Pa · s ρ = density, kg∕m 3 σ = pressure ratio φ = recess angle, deg Subscripts a = atmosphere cr = critical l = liquid li = liquid injector g = gas ir = inner or = outer r = recess s = swirl chamber t = tangential hole

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Section: A Experimental Facilitiesmentioning

confidence: 99%

Effects of Recess on the Self-Pulsation Characteristics of Liquid-Centered Swirl Coaxial Injectors

Kang

Cheng

et al. 2016

Journal of Propulsion and Power

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“…according recess length demonstrated. 4 Canino et al showed the frequency and variation of exit mass flow rate oscillation by numerical study. They found that the time averaged film thickness at the exit monotonically decreased as the recess length increased.…”

Section: Introductionmentioning

confidence: 98%

Measurement of Film Thickness in Gas-Centered Swirl Coaxial Injectors

Park¹,

Lee²,

Lee³

et al. 2014

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

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A number of study of Gas-Centered Swirl Coaxial(GCSC) injectors that have been used for stage-combustion cycle engine with high efficiency have been conducted in the last few decades. GCSC injectors that supply the oxidizer-rich gas generated from pre-burner is injected to the center of injectors in the form of jet. At the same time swirled liquid fuel is wrapped around the gas jet. The study was conducted to find the characteristics of spray varying the momentum flux ratio and recess ratio which are known as important parameter of coaxial injectors. This study measured the spray angle and film thickness of gas-centered swirl coaxial injector according to momentum flux ratio and recess ratio. The film thickness is measured by using electrical conductance method. Also the variation of spray angle was obtained by the backlight image method. It was found that the spray angle and film thickness were changed according to the critical momentum flux ratio. Nomenclature d = diameter of gas orifice d = diameter of tangential inlet d = diameter of liquid orifice ℎ = gap thickness between liquid orifice and gas orifice L = recess length MR = momentum flux ratio = critical momentum flux ratio of spray angle = critical momentum flux ratio of film thickness ̇ = liquid mass flow rate n = number of tangential inlet RR = recess ratio r = radius of tangential inlet t = film thickness = gas velocity = liquid axial velocity ∆p = pressure drop µ = coefficient of liquid viscosity ρ = density of gas ρ = density of liquid

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“…1,2 Gas-centered swirl coaxial injectors, a specific type of prefilming airblast atomizer, have seen an increase in interest over the last decade. [3][4][5][6] They have high performance at the flow conditions typical in OX rich staged combustion cycles, especially those involving rocket-grade kerosene (RP). This type of element was also used successfully in Russian rocket engines employing an OX rich staged combustion cycle (eg, .…”

Section: Introductionmentioning

confidence: 99%

“…7 However, the basic scaling and design criteria were not well documented and physics-based models did not exist. Because the interest, throughout the world, in RP-GOX and OX rich staged combustion cycles has been on the rise in recent years, [3][4][5][6] much effort has been placed on constructing the needed design and scaling methodologies.…”

Section: Introductionmentioning

confidence: 99%

Effect of Swirl on Gas-Centered Swirl-Coaxial Injectors

Schumaker¹,

Danczyk²

2011

47th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Physics-based scaling laws and design methodologies for gas-centered swirl-coaxial injectors have been under consideration for several years. Prior work showed that scaling via a momentum flux ratio was promising. However, that work neglected the effects of liquid swirl on the atomization. This current work refines the definition of the momentum flux ratio by adding compressibility in the gas phase and using a total liquid velocity. The focus, however, is on the impact of swirl through the study of different liquid inlet configurations. The film length and character are studied for a range of swirl values with ratios of axial to total velocity ranging from 26 to 41 percent. The new definition of momentum flux ratio collapses film length data onto a single curve over the range of swirl levels and interior injector geometries. The character of the film is seen to change, particularly in regards to gas entrainment into the film, as the swirl is decreased. Changes in swirl have little impact on film length; this is anticipated because the centripetal forces are several orders of magnitude lower than the aerodynamic forces driving atomization. Some examination of an inlet with no swirl (axial to total velocity ratio of 100 percent) is also presented. NomenclatureA surf = Surface area of a disturbance on the film's surface A* = Calculated throat area Fr c = PseudoFroude number for centripetal force L C = Injector cup length L f = Liquid film length ṁ = Mass flow rate R A = Ratio of axial to total film velocity at injector lip r g = Initial injector gas post radius r o = Injector outlet radius r p = Injector gas post radius at end of sheltered lip Re = Reynolds Number s = Injector step height at end of sheltered lip v = Velocity Vol = Volume We = Weber number of the liquid X = Downstream coordinate Y = Radial coordinate Ф = Gas to liquid momentum flux ratio ρ = Density τ = Initial liquid film thickness Subscripts axial = Denotes axial component of the liquid velocity dis = Of a disturbance on the film's surface g = Denotes a gas property l = Denotes a liquid property tan = Denotes tangential component of the liquid velocity total = Denotes total liquid velocity 1 Aerospace Engineer, RZSA, 10 E.

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Comparative Study of Spray Characteristics of Gas-Centered and Liquid-Centered Swirl Coaxial Injectors

Cited by 57 publications

References 10 publications

Effects of Recess on the Self-Pulsation Characteristics of Liquid-Centered Swirl Coaxial Injectors

Effects of Recess on the Self-Pulsation Characteristics of Liquid-Centered Swirl Coaxial Injectors

Measurement of Film Thickness in Gas-Centered Swirl Coaxial Injectors

Effect of Swirl on Gas-Centered Swirl-Coaxial Injectors

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