Study on Design- and Operation- Parameters of Supersonic Exhaust Diffuser

Sung, Hong-Gye; Yoon, Sangkyu; Yeom, Hyo-Won; Kim, Jinkon; Kim, Yong-Wook; Ko, Yongsung; Oh, Seunghyup

doi:10.2514/6.2008-855

Cited by 4 publications

(12 citation statements)

References 7 publications

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“…The un-started zone has been identified from A-B in Figure 4, P 0 /P a varies from 10 to 40, and started region is identified as B-C, and it ranges from P 0 /P a varies from 40 to 60. The wall pressures obtained from the CFD analyses is compared with the experimental and CFD computations 9 and shown in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

“…The value of turbulent Prandtl number in the present simulations is taken as 0.9 as the flow is dominated by the interaction with solid boundaries of nozzle and diffuser walls 16 . High pressure nitrogen gas at normal temperature is utilised in both the experimental cases [9][10] being considered in the present study. The supply pressure of the gas is taken as chamber pressure of the rocket motor (P 0 in Fig.…”

Section: Cfd Methodologymentioning

confidence: 99%

“…There are two different geometries considered for the numerical study of SEDs [9][10] . Both these geometries conform to the schematic sketch as shown in Fig.…”

Section: Geometries and Gridsmentioning

confidence: 99%

“…1. The impingement of the rocket jet on SED wall and vacuum level in the chamber is shown to be a function of nozzle throat area (A t ), duct cross sectional area (A d ), duct exit area (A e ), and ratio of the specific heats (γ) of the products of combustion 9 .…”

Section: Introductionmentioning

confidence: 99%

“…An SED consists of a vacuum chamber, cylindrical supersonic diffuser and a subsonic diffuser. The working principle of the SED is explained in detail in literature [8][9][10] . A schematic layout of an SED with a rocket motor to be tested is as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Characterisation of Supersonic Exhaust Diffusers

2017

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Section: Resultsmentioning

confidence: 99%

Section: Cfd Methodologymentioning

confidence: 99%

“…There are two different geometries considered for the numerical study of SEDs [9][10] . Both these geometries conform to the schematic sketch as shown in Fig.…”

Section: Geometries and Gridsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Characterisation of Supersonic Exhaust Diffusers

2017

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Optimization of Second Throat Ejectors for High-Altitude Test Facility

Kumaran¹,

Vivekanand²,

Sundararajan³

et al. 2009

Journal of Propulsion and Power

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In the present work, a second throat ejector using nitrogen as the primary fluid is considered for the creation of a low vacuum in a high-altitude testing facility for large-area-ratio rocket motors. Detailed numerical investigations have been carried out to evaluate the performance of the ejector for various operational conditions and geometric parameters during the nonpumping and pumping modes of operation. In the nonpumping mode, the lowest vacuum chamber pressure is attained when the primary jet just expands up to the mixer throat and the resulting single shock cell seals the throat against any backflow. The study illustrates how each geometric and operational parameter of the ejector can be optimized to meet the test requirements in a high-altitude testing facility by ensuring that the primary jet completely expands without a strong impact on the duct wall. When the rocket motor is fully started, due to the self-pumping action, the required vacuum is almost maintained by the exhaust flow itself and the external nitrogen ejector plays only a supplementary role. Numerical predictions for both nonpumping and pumping modes of operation have been validated with experimental data obtained from a scaled-down model of a high-altitude testing facility.Nomenclature d 0 = ejector inlet diameter d 1 = primary nozzle throat diameter d 2 = primary nozzle exit diameter d 3 = mixer throat diameter L 1 = length of the entry duct L 2 = length of the mixing cone L 3 = length of the mixer throat L 4 = length of the divergent duct L 5 = length from primary nozzle exit to mixer throat entrance _ m 1 = flux of secondary flow (rocket exhaust water spray) _ m 2 = flux of primary flow (gaseous nitrogen) P = pressure q = heat transfer per unit area v = velocity = mixing cone convergent angle = entrainment ratio (ratio of secondary mass flux to primary mass flux) = density rr = normal stress in radial direction zr , rz = tangential stress zz = normal stress in axial direction = hoop stress = viscous dissipation Subscripts c = chamber p = primary r = radial s = suction (secondary) v = vacuum z = axial

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