Computational/experimental study of a variable critical nozzle flow

Kim, Jae-Hyung; Kim, Heuy Dong; Park, Kyung-Am

doi:10.1016/j.flowmeasinst.2005.11.002

Cited by 16 publications

(11 citation statements)

References 11 publications

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“…6 and 7 show the variation of the discharge coefficient Cd with the Reynolds number [5][6][7]. The present computations predicts the measured discharge coefficients for α = 2° well, regardless of the supply pressure level.…”

Section: Resultsmentioning

confidence: 52%

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Effect of diffuser angle on the discharge coefficient of miniature critical nozzles

Kim

2010

J Mech Sci Technol

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Many studies on critical nozzles have been made to accurately measure the mass flow rate of gas and standardize its performance as a flow meter. Recently, much interest has been given to measuring very small mass flow rates in industrial fields, such as MEMS applications. However, the design and performance data of the critical nozzles obtained thus far have been applied mainly to critical nozzles with comparatively large diameters, and available studies on miniature critical nozzles are lacking. In this study, computational fluid dynamics (CFD) method was applied to investigate the influence of the diffuser angle on the discharge coefficient of miniature critical nozzles. In computations, the throat diameter of a critical nozzle varied from 0.2 to 5.0 mm, and the diffuser angle changed from 2° to 8°. The computational results were validated with some available experimental data. The present computational results accurately predicted the discharge coefficient of gas flows through miniature critical nozzles. The discharge coefficient is considerably influenced by the diffuser angle as the throat diameter of the nozzle becomes smaller below a certain value. This implies that miniature critical nozzles should be designed with careful consideration of its effects.

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Section: Resultsmentioning

confidence: 52%

“…In the critical nozzle flow, the discharge coefficient is a function of the Reynolds number based on velocity at the nozzle throat and diameter of the nozzle throat [3][4][5]. At high Reynolds numbers, the discharge coefficient approaches unity, indicating that the one-dimensional, inviscid theory reasonably predicts mass flow.…”

Section: Introductionmentioning

confidence: 99%

Effect of diffuser angle on the discharge coefficient of miniature critical nozzles

Kim

2010

J Mech Sci Technol

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“…6 and 7 show the variation of the discharge coefficient with Reynolds number. As described in many previous works [5][6][7], the coefficient of discharge Cd is expressed by a function of Reynolds number. It is known that the present computations predict well the measured discharge coefficients for α = 2 o , regardless of the supply pressure level, obviously showing a general trend of the divergent angle.…”

Section: Resultsmentioning

confidence: 99%

“…A considerable number of researches have been carried out to establish the measurement standard of gas flow using critical nozzle. According to their works [3][4][5], the coefficient of discharge and critical pressure ratio are strong functions of the Reynolds number, based upon the velocity at nozzle throat and the diameter of nozzle throat. At high Reynolds numbers, the coefficient of discharge approaches unity, indicating that the one-dimensional, inviscid theory reasonably predicts the mass flow.…”

Section: Introductionmentioning

confidence: 99%

The effect of diffuser angle on the discharge coefficient of a miniature critical nozzle

Kim

Setoguchi

2010

J. Therm. Sci.

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Many researches on critical nozzles have been performed to accurately measure the mass flow rate of gas flow, and to standardize the performance as a flow meter. Recently, much interest is being paid on the measurement of very small mass flow rate in industry fields such as MEMS applications. However, the design and performance data of the critical nozzles obtained so far have been applied mainly to the critical nozzles with comparatively large diameters, and the works available on miniature critical nozzles are lacking. In the present study, a computational fluid dynamics method has been applied to investigate the influence of the diffuser angle on discharge coefficient of the miniature critical nozzles. In computations, the throat diameter of critical nozzle is varied from 0.2 mm to 5.0 mm and the diffuser angle is changed from 2 deg to 8 deg. The computational results are validated with some experimental data available. The results show that the present computational results predict appropriately the discharge coefficient of the gas flows through miniature critical nozzles. It is known that the discharge coefficient is considerably influenced by the diffuser angle, as the throat diameter of nozzle becomes small below a certain value. This implies that the miniature critical nozzles should be carefully designed.

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“…The 2D with boundary layer model is developed to study the boundary-layer effect on the nozzle contour. Of primary concern are the boundary layer's displacement thickness and growth effect on mass flow (Kim et al 2005) and flow expansion. Experimental work on axis-symmetrical nozzles (Grisnik et al 1987) have shown that viscous effects start to reduce nozzle thrust for Reynolds number below 9 10 3 , and even more below 4 10 3 , which is in the range of the tests.…”

Section: Computational Fluid Dynamics Modelingmentioning

confidence: 99%

Planar Nozzles for Controllable Microthrusters

2017

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Orbital maneuvering of microsatellite and nanosatellite requirements can be efficiently addressed by planar nozzles, in which realtime thrust control is gained actuating on the nozzle throat area. In the present work, the method of characteristics is used to design a hypersonic contour; then, the resulting profile is laser cut, assembled, and built into a propulsion system to finally perform tests in a vacuum chamber under several working conditions. Results are used to validate the profile and modeling assumptions and investigate overall behavior. Tests showed that thrust-inlet pressure ratio is a linear function of separation between nozzle contours and that no additional losses are introduced in the system. The corresponding design/manufacture/assembly tools can be used to a provide low-cost/low-weight controllable propulsion systems to the small-satellite industry with no efficiency loss.

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Computational/experimental study of a variable critical nozzle flow

Cited by 16 publications

References 11 publications

Effect of diffuser angle on the discharge coefficient of miniature critical nozzles

Effect of diffuser angle on the discharge coefficient of miniature critical nozzles

The effect of diffuser angle on the discharge coefficient of a miniature critical nozzle

Planar Nozzles for Controllable Microthrusters

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